Telecommunications
Telephone Terminal Equipment
Transmission Requirements for
Narrowband Digital Telephones
SP-3-4352-RV2 (to become ANSI/TIA-810-B)
Default ballot
August, 2006
SP-3-4352-RV2 (to become ANSI/TIA-810-B)
TABLE OF CONTENTS
1.
INTRODUCTION ..................................................................................................................... 1
2.
SCOPE........................................................................................................................................ 2
2.1.
2.2.
LIMITS OF APPLICABILITY ................................................................................................ 2
CATEGORIES OF CRITERIA ................................................................................................ 3
2.3.
FCC PART 68 ....................................................................................................................... 3
2.4.
2.5.
ENVIRONMENTAL .............................................................................................................. 3
SAFETY ................................................................................................................................ 3
3.
NORMATIVE REFERENCES ................................................................................................ 4
4.
DEFINITIONS, ABBREVIATIONS AND ACRONYMS ..................................................... 5
4.1.
CODEC ................................................................................................................................. 5
4.2.
4.3.
4.4.
4.5.
4.6.
4.7.
EAR REFERENCE POINT (ERP) .......................................................................................... 5
ARTIFICIAL EAR/MOUTH VS. EAR/MOUTH SIMULATOR............................................... 5
HATS POSITION .................................................................................................................. 5
NOMINAL VOLUME CONTROL SETTING ......................................................................... 5
REFERENCE VOLUME CONTROL SETTING ...................................................................... 5
PREFERRED EAR SIMULATOR ........................................................................................... 5
4.8.
4.9.
4.10.
STANDARD TEST POSITION .............................................................................................. 5
RECOMMENDED TEST POSITIONS (RTP) ......................................................................... 6
MOUTH REFERENCE POINT (MRP) .................................................................................. 6
4.11.
4.12.
4.13.
4.14.
4.15.
QUIET AND FULL SCALE CODE ........................................................................................ 6
REFERENCE CODEC ........................................................................................................... 7
DIRECT DIGITAL PROCESSING ......................................................................................... 7
SOUND PRESSURE LEVELS................................................................................................ 8
ELECTRIC POWER AND NOISE LEVELS ........................................................................... 9
4.16.
4.17.
50TP ..................................................................................................................................... 9
ABBREVIATIONS AND ACRONYMS .................................................................................. 9
5.
GENERAL TECHNICAL REQUIREMENTS .................................................................... 10
6.
HANDSET TECHNICAL REQUIREMENTS ..................................................................... 11
6.1.
HANDSET FREQUENCY RESPONSE................................................................................. 11
6.1.1. Handset Send Frequency Response ............................................................................ 11
6.1.2. Handset Receive Frequency Response ....................................................................... 13
6.2.
HANDSET LOUDNESS RATINGS AND RECEIVE VOLUME CONTROL .......................... 15
6.2.1. Handset Send Loudness Rating (SLR) ....................................................................... 15
6.2.2. Handset Receive Loudness Rating (RLR) .................................................................. 15
6.2.3. Handset Receive Volume Control Range ................................................................... 15
6.2.4. Magnetic Field for Hearing Aid Coupling .................................................................. 16
6.2.5. Handset Talker Sidetone (STMR) .............................................................................. 16
6.2.6. Handset Sidetone Delay .............................................................................................. 17
6.3.
HANDSET NOISE ............................................................................................................... 17
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SP-3-4352-RV2 (to become ANSI/TIA-810-B)
6.3.1. Handset Send Noise ..................................................................................................... 17
6.3.2. Handset Send Single Frequency Interference.............................................................. 17
6.3.3. Handset Receive Noise ................................................................................................ 18
6.3.4. Handset Receive Single Frequency Interference ......................................................... 18
6.4.
HANDSET RECEIVE COMFORT NOISE (ADVISORY) ...................................................... 18
6.4.1. General ........................................................................................................................ 18
6.4.2. Measurement Method .................................................................................................. 18
6.4.3. Requirement ................................................................................................................ 19
6.5.
HANDSET DISTORTION AND NOISE ................................................................................ 19
6.5.1. Handset Send Distortion and Noise............................................................................. 19
6.5.2. Handset Receive Distortion and Noise ........................................................................ 20
6.6.
WEIGHTED TERMINAL COUPLING LOSS (TCLW) ......................................................... 20
6.6.1. Measurement Method .................................................................................................. 21
6.6.2. Requirements ............................................................................................................... 21
6.7.
STABILITY LOSS ............................................................................................................... 22
6.7.1. Measurement Method .................................................................................................. 22
6.7.2. Requirement ................................................................................................................ 23
6.8.
LONG DURATION MAXIMUM ACOUSTIC PRESSURE (STEADY STATE INPUT) .......... 23
6.8.1. General ........................................................................................................................ 23
6.8.2. Measurement Method .................................................................................................. 23
6.8.3. Requirements ............................................................................................................... 24
6.9.
SHORT DURATION MAXIMUM ACOUSTIC PRESSURE (PEAK) ..................................... 24
6.9.1. General ........................................................................................................................ 24
6.9.2. Measurement Method .................................................................................................. 24
6.9.3. Requirements ............................................................................................................... 24
6.10. VOIP TELEPHONE DELAY ................................................................................................ 24
6.10.1. Requirement ............................................................................................................... 24
6.10.2. Handset Send Delay ................................................................................................... 24
6.10.3. Handset Receive Delay............................................................................................... 25
7.
HEADSET TECHNICAL REQUIREMENTS...................................................................... 26
7.1.
HEADSET FREQUENCY RESPONSE.................................................................................. 26
7.1.1. Headset Send Frequency Response ............................................................................. 26
7.1.2. Headset Receive Frequency Response ........................................................................ 27
7.2.
HEADSET LOUDNESS RATINGS ....................................................................................... 28
7.2.1. Headset Send Loudness Rating (SLR) ........................................................................ 28
7.2.2. Headset Receive Loudness Rating (RLR) ................................................................... 29
7.2.3. Headset Talker Sidetone (STMR) ............................................................................... 29
7.3.
HEADSET NOISE ................................................................................................................ 30
7.3.1. Headset Send Noise ..................................................................................................... 30
7.3.2. Headset Send Single Frequency Interference .............................................................. 30
7.3.3. Headset Receive Noise ................................................................................................ 30
7.3.4. Headset Receive Single Frequency Interference ......................................................... 31
7.4.
HEADSET DISTORTION AND NOISE ................................................................................ 31
7.4.1. Headset Send Distortion and Noise ............................................................................. 31
7.4.2. Headset Receive Distortion and Noise ........................................................................ 32
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7.5.
WEIGHTED TERMINAL COUPLING LOSS (TCLW) ........................................................ 32
7.5.1. Measurement Method ................................................................................................. 32
7.5.2. Requirements .............................................................................................................. 33
7.6.
LONG DURATION MAXIMUM ACOUSTIC PRESSURE (STEADY STATE INPUT) ......... 34
7.6.1. General ........................................................................................................................ 34
7.6.2. Measurement Method ................................................................................................. 34
7.6.3. Requirements .............................................................................................................. 34
7.7.
SHORT DURATION (PEAK) ACOUSTIC PRESSURE ........................................................ 35
7.7.1. General ........................................................................................................................ 35
7.7.2. Measurement Method ................................................................................................. 35
7.7.3. Requirements .............................................................................................................. 35
8.
HANDSFREE TECHNICAL REQUIREMENTS ............................................................... 36
8.1.
HANDSFREE FREQUENCY RESPONSE ............................................................................ 36
8.1.1. Handsfree Send Frequency Response ......................................................................... 36
8.1.2. Handsfree Receive Frequency Response .................................................................... 38
8.2.
HANDSFREE LOUDNESS RATINGS AND RECEIVE VOLUME CONTROL ..................... 39
8.2.1. Handsfree Send Loudness Rating (SLR) .................................................................... 39
8.2.2. Handsfree Receive Loudness Rating (RLR) ............................................................... 40
8.2.3. Handsfree Receive Volume Control ........................................................................... 40
8.3.
HANDSFREE NOISE .......................................................................................................... 40
8.3.1. Handsfree Send Noise ................................................................................................. 40
8.3.2. Handsfree Send Single Frequency Interference .......................................................... 41
8.3.3. Handsfree Receive Noise ............................................................................................ 41
8.3.4. Handsfree Receive Single Frequency Interference ..................................................... 41
8.4.
HANDSFREE DISTORTION AND NOISE ........................................................................... 42
8.4.1. Handsfree Send Distortion and Noise ......................................................................... 42
8.4.2. Handsfree Receive Distortion and Noise .................................................................... 42
8.5.
WEIGHTED TERMINAL COUPLING LOSS (TCLW) ........................................................ 43
8.5.1. Measurement Method ................................................................................................. 43
8.5.2. Requirements .............................................................................................................. 43
8.6.
STABILITY LOSS ............................................................................................................... 44
8.6.1. Measurement Method ................................................................................................. 44
8.6.2. Requirement ................................................................................................................ 44
ANNEX A
(NORMATIVE) – CALCULATION OF LOUDNESS RATINGS....................... 45
ANNEX B
(INFORMATIVE) – MEASUREMENT AND LEVEL CONVERSIONS .......... 48
ANNEX C
(INFORMATIVE) – PREFERRED 1/12TH OCTAVE FREQUENCIES............. 50
ANNEX D
(INFORMATIVE) – NOMINAL HANDSET FREQUENCY RESPONSE
DERIVATION .................................................................................................................................... 51
ANNEX E
(INFORMATIVE) – SDN ERRONEOUS RESULT EXAMPLE ........................ 65
ANNEX F
(INFORMATIVE) – BIBLIOGRAPHY ................................................................. 66
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SP-3-4352-RV2 (to become ANSI/TIA-810-B)
FOREWORD
(This foreword is not part of this standard.)
This document is a TIA/EIA Telecommunications standard produced by Working Group
TR-41.3.3 of Committee TR-41. This standard was developed in accordance with TIA/EIA
procedural guidelines, and represents the consensus position of the Working Group and its parent
Subcommittee TR-41.3, which served as the formulating group. This standard is based on
ANSI/TIA/EIA-810-A.
The TR-41.3.3 VoIP/PCM Transmission Performance Working Group acknowledges the
contribution made by the following individuals in the development of this standard.
Name
Ken Macdonald
Roger Britt
John Bareham
Al Baum
Ruchir Dave
Miguel DeAraujo
Steve Graham
Tom Harley
Glenn Hess
Ron Magnuson
Kirit Patel
Joachim Pomy
Amar N. Ray
Allen Woo
Bob Young
Representing
Microtronix Systems Ltd.
Nortel
Consultant in Electroacoustics
Uniden
Cisco Systems
Nortel
Plantronics
Texas Instruments
MWM Acoustics
Acoustics for Communications
Cisco Systems
Avaya
Embarq
Plantronics
IEEE STIT
Chair
Editor
Copyrighted parts of ITU-T Recommendation P.79 are used with permission of the ITU. The ITU
owns the copyright for the ITU Recommendations. Copyrighted parts of ISO 3 are used with
permission of the ISO. The ISO owns the copyright for the ISO Standards.
The four annexes in this Standard are informative and are not considered part of this Standard.
Suggestions for improvement of this standard are welcome. They should be sent to:
Telecommunications Industry Association
Engineering Department
Suite 300
250 Wilson Boulevard
Arlington, VA 22201
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SP-3-4352-RV2 (to become ANSI/TIA-810-B)
1. Introduction
This revision of ANSI/TIA/EIA-810-A establishes handset, headset and handsfree telephone audio
performance requirements for digital telephones regardless of protocol or digital format. A number of
improvements and corrections have been made, particularly related to the use of ear simulators.
This standard addresses conventional narrowband performance, where narrowband is defined as the
frequency range between 300 and 3400 Hz. Requirements for wideband telephony, in the frequency
range between 150 and 6800 Hz are defined in TIA-920.
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SP-3-4352-RV2 (to become ANSI/TIA-810-B)
2. Scope
This standard establishes voice performance requirements for narrowband digital telephones and
devices. Transmission may be over any digital interface including wired, or wireless, Local or Wide
Area Networks, Firewire/IEEE Std 1394, Universal Serial Bus (USB), public ISDN or digital over
twisted pair wire. This includes TDM-based and packet-based (e.g. VoIP) telephones. These
telephones may be connected through modems, Voice Gateways, wireless access points, PBXs, or
personal computer-based telephones. Examples include: ISDN telephones, digital proprietary
telephones, VoIP telephones (corded and cordless), softphones (such as laptop computers), IEEE
802.11 telephones, USB telephones, USB devices, DECT telephones, Bluetooth® Telephones and
Bluetooth devices.
In principle, this document can be used to evaluate wireless devices and other devices where the Alaw and mu-law codecs are not supported for the full audio channel. In this case the targets specified
in this standard may not apply. If A-law or mu-law codecs are supported they shall be used for testing
to compliance to this standard.
For telephone systems that incorporate a Universal Serial Bus (USB) type interface or a Bluetooth
type interface to a host (such as laptop computers), it may be desirable for the USB or Bluetooth
device to meet the requirements of relevant clauses of this standard, where the host device is assumed
to have a 0 dB loss plan, in its default state. It may be desirable for the device to provide gain
adjustment for both the send and receive channels. When connected to a host device, the full system
shall then meet all of the associated requirements of this standard. A USB or Bluetooth device may
have a handset, headset or speakerphone configuration.
Technical requirements are specified for handset, headset and handsfree (speakerphone) modes of
operation regardless of the technology used to couple the handset or headset to the telephone.
The test measurement methods in this standard reference procedures in IEEE Std 269 and IEEE Std
1329 where applicable, as well as the appropriate ITU-T Recommendations. Several performance
measurement procedures are established which can be used for the determination of compliance with
this standard. Although this document may reference specific procedures or test equipment the intent
is not to be all-inclusive. Any measurement procedure and equipment that can provide adequate
results within the accuracy of the original measurement is considered valid.
NOTE - If the main purpose for testing to this standard is comparison testing of different
products, rather than compliance testing, then it is important that identical test procedures
and equipment be used when testing the different products.
While the procedures may call out specific test points within the requirements, the full range of the
requirements take precedence.
2.1. Limits of Applicability
This standard is not intended to describe specific requirements for the following types of digital
voice terminal equipment: telephones with carbon transmitters, ISDN terminal adapters, cellular
voice terminals (cell phones), and group audio terminals.
1
Bluetooth is a registered trademark of the Bluetooth SIG. This standard and TIA do not endorse
Bluetooth products or services.
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SP-3-4352-RV2 (to become ANSI/TIA-810-B)
2.2. Categories of Criteria
Mandatory requirements are designated by the word "shall". Advisory requirements are designated
by the word "should," or "may," or "desirable" which are used interchangeably in this standard.
Advisory criteria represent product goals or are included in an effort to ensure universal product
compatibility. Where both a mandatory and an advisory level are specified for the same criterion, the
advisory level represents a goal currently identifiable as having distinct compatibility or performance
advantages toward which future designs should strive.
2.3. FCC Part 68
This standard is intended to be in conformity with Part 68 of the Federal Communications
Commission (FCC) Rules and Regulations, but is not limited to the scope of those rules. In the event
that Part 68 requirements are more stringent than those contained in this standard, the provisions of
Part 68 apply.
2.4. Environmental
This standard does not contain environmental requirements. Environmental requirements can be
found in ANSI/TIA/EIA-571-A.
2.5. Safety
This standard does not contain safety requirements. Compliance with the applicable UL and CSA
safety standards may be required in certain locations.
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3. Normative References
The following standards contain provisions, which, through reference in this text, constitute
provisions of this Standard. At the time of publication, the editions indicated were valid. All
standards are subject to revision, and parties to agreements based on this Standard are encouraged to
investigate the possibility of applying the most recent editions of the standards indicated below, or
their successors. ANSI and TIA maintain registers of currently valid national standards.
[1]
ANSI/IEEE Standard 269a-2006, Standard Methods for Measuring Transmission
Performance of Analog and Digital Telephone Sets, Handsets and Headsets.
[2]
ANSI/IEEE Standard 1329-1999, Standard
Performance of Handsfree Telephone Sets.
[3]
ANSI S1.4-1990, Sound Level Meters.
[4]
ASTM D 2240-2002, Standard Test Method for Rubber Property - Durometer Hardness.
[5]
ITU-T Recommendation G.122 (03/1993), Influence of national systems on stability and
talker echo in international connections.
[6]
ITU-T Recommendation G.711 (11/1988), Pulse code Modulation (PCM) of voice
frequencies.
[7]
ITU-T Recommendation O.41 (10/1994), Psophometer for use on telephone-type circuits.
[8]
ITU-T Recommendation O.131 (11/1988), Quantizing distortion measuring equipment using
a pseudo-random noise test signal.
[9]
ITU-T Recommendation P.51 (1996), Artificial Mouths.
[10]
ITU-T Recommendation P.53 (1994), Psophometer for use on telephone-type circuits.
[11]
ITU-T Recommendation P.57 (11/2005), Artificial ears.
[12]
ITU-T Recommendation P.64 (09/1999),
characteristics of local telephone systems.
[13]
ITU-T Recommendation P.1010 (7/2004), Fundamental voice transmission objectives for
VoIP terminals and gateways.
4
Method for Measuring Transmission
Determination
of
sensitivity/frequency
SP-3-4352-RV2 (to become ANSI/TIA-810-B)
4. Definitions, Abbreviations and Acronyms
For the purposes of this Standard, the following definitions apply.
4.1. Codec
A codec is a combination of an analog-to-digital encoder and a digital-to-analog decoder operating in
opposite directions of transmission in the same equipment.
4.2. Ear Reference Point (ERP)
A virtual point for geometric reference located at the entrance to the listener's ear, traditionally used
for calculating telephonometric loudness ratings.
4.3. Artificial Ear/Mouth vs. Ear/Mouth Simulator
This standard uses the terms “ear simulator” and “mouth simulator” synonymously with the terms
“artificial ear” (ITU-T P.57) and “artificial mouth” (ITU-T P.51), respectively, to harmonize with
IEEE Std 269.
4.4. HATS Position
The HATS (head and torso simulator) position (ITU-T P.64 Annex D and Annex E) is the correct
handset position for measuring sensitivity and frequency response characteristics. The HATS
position has been shown to be essentially identical to the LRGP (loudness rating guard-ring position)
position, except for the mouth simulator direction, which has been corrected with a 19 degrees
downwards rotation to more closely match real talkers. For handsets with omnidirectional
microphones, measurements on the two heads may differ slightly, typically less than 1dB. For
handsets with directional or noise-canceling microphones, the differences will be larger, and the
HATS position will give the more realistic results. Some equipment may use the term “LRGP-H” for
the HATS position.
4.5. Nominal Volume Control Setting
The nominal volume control setting is the receive volume control setting that results in the RLR
closest to the nominal RLR value. All tests shall be performed with the receive volume control set to
the nominal volume control setting, unless otherwise specified.
For handsets the RLR is measured with the receiver in the high leak position.
4.6. Reference Volume Control Setting
The reference volume control setting is the quietest volume control setting that complies with the
mandatory low leak RLR requirement in 6.2.3, unless the manufacturer specifies a different reference
volume control setting that also complies with the mandatory low leak RLR requirement in 6.2.3.
4.7. Preferred Ear Simulator
The preferred ear simulator is the Type 3.3. For alternative ear simulators, see relevant sections of
IEEE Std 269.
4.8. Standard Test Position
The Standard Test Position consists of a high leak position and a low leak position.
The high leak position is defined as the Type 3.3 ear simulator with the receiver contacting the pinna
with a force of 10N.
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The low leak position is defined as the Type 3.3 ear simulator with the receiver contacting the pinna
with a force of 18 N.
4.9. Recommended Test Positions (RTP)
RTP for a handset may be defined (using coordinates as defined in ITU-T P.64, Annex E) by
following these steps:
1. Find the Ear-Cap Reference Point (ECRP) on the handset. Unless otherwise specified by the
manufacturer, the ECRP is the intersection of the external ear-cap reference plane with a
normal axis through the effective acoustic center of the sound outlet ports. Generally, the
acoustic center of the sound outlet ports is at the center of their distribution. For some
handsets, the ear cap reference plane has to be estimated. For example, a tangent to a curved
surface at the effective acoustic center.
2. Line up the handset ECRP at the Ear simulator ERP on the positioning device. The ear cap
reference plane shall be identical to the reference plane of the positioning device. When the
positioning device is set to ERP, then the ear cap reference plane, the reference plane of the
positioning device and the ERP plane are identical.
3. Translation: Move the handset ECRP in ear cap reference plane relative to ERP along the ye
and/or ze axis. If no coordinates are given, leave the ECRP centered on ERP, equivalent to
(0, 0) coordinates. The ye -axis is defined along the length of the handset with positive ye
being in a direction towards the microphone from ECRP. Positive ze axis is in a downward
direction towards the floor.
4. Rotation: Adjust the angle(s) of the handset positioner about the ERP of the coordinate
system.
5.
If no coordinates are given, use angles consistent with the HATS position.
6. Application of force: Adjust pressure or distance along the axis of motion of the positioning
device. This axis is defined by a line that passes through the ERP of the left and right ears. It
is parallel to the Ym axis. If no force or position is given, use 6N.
7. RTP can then be defined as the combination of the above translation, rotation and force
specifications. The manufacturer of the device under test is responsible for providing this
data.
4.10.
Mouth Reference Point (MRP)
The mouth reference point is located on axis and 25 mm in front of the lip ring of a mouth simulator.
4.11.
Quiet and Full Scale Code
Table 1 – PCM Codes for Zero (Quiet Code) and Full Scale
Level
+ Full Scale
+ Zero
- Zero
- Full Scale
Sign Bit
1
1
0
0
Mu-Law
Chord Bit
000
111
111
000
Step Bits
0000
1111
1111
0000
6
Sign Bit
1
1
0
0
A-Law
Chord Bits
010
101
101
010
Step Bits
1010
0101
0101
1010
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4.12.
Reference Codec
A reference codec is used for testing digital telephone terminals with analog test equipment. Figure 1
shows the basic test setup using a reference codec. A codec that approaches an ideal codec and has
superior, well-defined, characteristics qualifies as a reference codec.
When a 0.775 volt rms analog signal is applied to the coder input, a 0 dBm0 digital code is present at
the digital reference. In general, when a 0 dBm0 digital code is applied to the decoder, a 0.775 volt
rms analog signal appears at the decoder output. More specifically, when the 0 dBm0 periodic
sequence as given in Table 2, in either mu-law or A-law as appropriate, is applied to the decoder at
the digital reference point, a 1 kHz, 0.775 volt rms sine-wave signal appears at the decoder output.
0 dBm0 is 3.14 (A-law) or 3.17 (mu-law) dB below digital full scale.
Table 2 – Mu-Law and A-Law 0 dBm0 Periodic Sequence that produces
a 1 kHz, 0.772 volt rms Sine-Wave Signal
1
0
0
0
0
1
1
1
1
2
0
0
0
0
0
0
0
0
3
0
0
0
0
0
0
0
0
Mu-Law
4
5
1
1
0
1
0
1
1
1
1
1
0
1
0
1
1
1
6
1
0
0
1
1
0
0
1
7
1
1
1
1
1
1
1
1
8
0
1
1
0
0
1
1
0
1
0
0
0
0
1
1
1
1
2
0
0
0
0
0
0
0
0
3
1
1
1
1
1
1
1
1
A-Law
4
5
1
0
0
0
0
0
1
0
1
0
0
0
0
0
1
0
6
1
0
0
1
1
0
0
1
7
0
0
0
0
0
0
0
0
8
0
1
1
0
0
1
1
0
This implementation of a reference codec eliminates the 600 ohm source and load resistors specified
by other standards. The coder input impedance is high relative to the generator and the decoder
output impedance is low relative to the measuring voltmeter.
The interface block, shown in Figures 1 and 2, passes the voice channel digital bit stream to the
terminal without modification. There is no gain or loss in the send or receive direction due to the
interface. If the interface does change the digital voice stream then the terminal and interface shall be
considered jointly as the terminal. An example of this is a receive volume control implemented in a
PBX or gateway.
4.13.
Direct Digital Processing
Direct digital generation of the receive signal and analysis of the send signal may be used in place of
the reference codec as shown in Figure 2. This method is preferred when possible.
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Figure 1 – Digital Telephone Set Test Arrangement with Reference Codec
Digital Reference
Point
(Junction j)
vSEND
Send
pM
Mouth Sound Pressure
at MRP
Digital
Set
Decoder
v
Coder
GEN
Interface
pE
Ear Sound Pressure
at ERP
vRCV
Receive
Reference Codec
Figure 2 – Digital Telephone Set Test Arrangement using Direct Digital Generation and
Analysis
Digital Reference
Point
(Junction j)
Send
Digital
Analysis
pM
Mouth Sound Pressure
at MRP
Digital
Interface
Set
Digital
Generation
pE
Ear Sound Pressure
at ERP
Receive
4.14.
Sound Pressure Levels
Sound pressure level is a value expressed as a ratio of the pressure of a sound to a reference pressure.
The following sound level units are used in this standard:
dBPa:
The sound pressure level, in decibels of a sound is 20 times the logarithm to the base 10 of
the ratio of the pressure of this sound to the reference pressure of
1 Pascal (Pa). Note: 1 Pa = 1 N/m2.
dBSPL: The sound pressure level, in decibels of a sound is 20 times the logarithm to the base 10 of
the ratio of the pressure of this sound to the reference pressure of
2 X 10-5 N/m2 (0 dBPa corresponds to 94 dBSPL).
dBA:
The A-weighted sound level is the sound pressure level in dBSPL, weighted by use of
metering characteristics and A-weighting specified in ANSI S1.4.
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4.15.
Electric Power and Noise Levels
The following electric power and noise level units are used in this standard:
dBm0:
The absolute power level at a digital reference point of the same signal that would be
measured as the absolute power level, in dBm, if the reference point was analog. The
absolute power in dBm is defined as 10 log (power in mW / 1 mW). When the impedance
is 600 ohm resistive, dBm can be referred to a voltage of 0.775 volts, which results in a
reference active power of 1 mW. Note that 0 dBm0 is not the maximum digital code. For
Mu Law codecs 0 dBm0 is 3.17 dB below digital full scale. For A Law codecs 0 dBm0 is
3.14 dB below digital full scale.
dBm0p: The noise level, measured by a psophometer with a special noise weighting filter as
described in ITU-T Recommendations O.41 and P.53. The small letter “p” comes from the
French word “ponderé”. The equivalent English word is “weighted”, but the “p” refers
specifically to psophometric weighting.
4.16.
50TP
The acoustic test point 50 cm from the front center of the handsfree telephone (HFT) and 30 cm
above the test table.
4.17.
Abbreviations and Acronyms
Abbreviations and acronyms, other than in common usage, which appear in this standard, are defined
below.
AGC
CSS
DRP
ERP
FFT
HATS
ISDN
LRGP
MRP
OLR
PBX
PCM
RLR
RTP
SLR
STMR
TCLw
VAD
VoIP
Automatic Gain Control
Composite Source Signal
Drum Reference Point
Ear Reference Point
Fast Fourier Transform
Head and Torso Simulator
Integrated Services Digital Network
Loudness Rating Guard-ring Position
Mouth Reference Point
Objective Loudness Rating
Private Branch Exchange
Pulse Code Modulation
Receive Loudness Rating
Recommended Test Position
Send Loudness Rating
Sidetone Masking Rating
Weighted Terminal Coupling Loss
Voice Activity Detector
Voice over Internet Protocol
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SP-3-4352-RV2 (to become ANSI/TIA-810-B)
5. General Technical Requirements
All telephones shall support G.711 A-law and mu-law. The technical requirements apply only to mulaw and A-law G.711 codecs. If the telephone uses other low-bit rate coders of the ITU-T G-series of
Recommendations, the manufacturer must ensure that their implementation passes the standard test
vectors associated with that codec.
Unless specified otherwise:




Encoding and decoding is assuming to be G.711 in mu-law. In particular, this applies to the
requirements in the Distortion and Noise sections.
Test methods are given in IEEE Std 269.
All Type 3.3 ear simulator measurements shall be transformed from the drum reference point
(DRP) to the ear reference point (ERP).
When sinewave stimulus is used the frequency tolerance is 3%, and even submultiples of the
sampling frequency (normally 8000 Hz) must not be used.
Algorithmic processes, such as Echo Control, VAD and AGC, may influence the test results or
require test signals other than sinewaves. IEEE Std 269 allows several types of test signals. The test
signal used should be stated. The test signal levels shall be equivalent to the test signal levels
specified in this standard. Test signal levels that differ from those specified in this standard may also
be required.
NOTE - The use of inappropriate test signals may result in erroneous test results.
Packet voice latency may introduce significant delay that must be accounted for by the test
equipment.
For telephones using nonlinear voice signal processing it may be desirable to conduct formal
subjective testing in accordance with ITU-T Recommendation P.800.
NOTE - For telephones where tandem codecs (other than G.711) are used (e.g. cordless
interface to a telephone set), the codec may affect the test results and some voice
transmission technologies may be unable to meet specified noise and/or distortion
requirements. Such devices need further investigation.
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SP-3-4352-RV2 (to become ANSI/TIA-810-B)
6. Handset Technical Requirements
All tests shall be performed with a Type 3.3 ear simulator with the handset in the HATS position.
The ear simulator shall comply with the specifications given in ITU-T Recommendation P.57
(11/2005). The Type 3.3 shall have a hardness of 35 ±6 degrees Shore-OO, as measured according to
ASTM 2240. (ITU-T Recommendation P.57 (07/2002) originally specified a hardness of 55 ±10
degrees Shore-OO for Type 3.3.)
Unless otherwise specified, all tests shall be performed in the Standard Test Position with the
receiver located at the high leak position. A manufacturer may specify Recommended Test Positions
for the high leak and the low leak positions. The RTP may specify the handset position with respect
to ERP, or other aspects of the test position intended to simulate actual use. If the terminal is tested
at the RTP, the RTP shall be documented and used for all handset tests.
All tests shall be preformed with the receive volume control set to the nominal volume control
setting, unless otherwise specified.
6.1. Handset Frequency Response
6.1.1. Handset Send Frequency Response
The send frequency response is the overall response of the transducer, send amplifier, and the codec
send filter. It is the ratio of the voltage output of the reference codec to the sound pressure at the
Mouth Reference Point (MRP) for each frequency or frequency band (Fi) as shown in the equation
below:
SMJ = 20 log (VSEND / PM) dB rel 1 V / Pa
Equation [1]
Where
SMJ
PM
VSEND
Send Sensitivity, Mouth to Junction, at Fi.
Sound pressure at the MRP at Fi.
RMS output voltage of the reference codec at Fi.
6.1.1.1.
Measurement Method
Measurements should be done in ISO 1/12th octave bands or R40 intervals, over a minimum range of
100 Hz through 4000 Hz using the measurement set-up shown in Figure 3. The test signal level shall
be 4.7 dBPa at the MRP.
Figure 3 – Handset Send Frequency Response Measurement Method
vSEND
HATS
Decoder
Measuring
Amplifier
Digital
GEN
Interface
Set
Send p M
Coder
Mouth Simulator
Quiet Room
Reference Codec
11
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SP-3-4352-RV2 (to become ANSI/TIA-810-B)
6.1.1.2.
Requirement
The send frequency response shall fall between the upper and lower limits given in Table 3 and
shown in Figure 4. The limit curves shall be determined by straight lines joining successive coordinates given in the table, where frequency response is plotted on a linear dB scale against
frequency on a logarithmic scale.
Table 3 – Co-ordinates of Handset Send Response
Limit Curve
upper limit
lower limit
Frequency
(Hz)
Send Response Limit
(dB) [arbitrary level]
200
1000
2000
3400
4000
<300
300
500
1000
3000
3400
>3400
+3
+3
+8
+8
+3
- infinity
-5
-3
-3
-1
-7
-infinity
Figure 4 – Handset Send Frequency Response Mask
Mandatory Limits
15
10
Arbitrary Level (dB)
5
0
-5
-10
-15
-20
100
1000
Frequency (Hz)
NOTE -The frequency response mask in Figure 4 is a floating or “best fit” mask.
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SP-3-4352-RV2 (to become ANSI/TIA-810-B)
Annex D provides additional tutorial material with respect to the nominal send frequency response
characteristic to illustrate the design intent of the limits. Send response is not specified below
200 Hz, but Annex D provides a ‘suggested’ nominal frequency response characteristic to complete
the design intent. See Annex D for the details on the derivation of the nominal frequency response
characteristics.
6.1.2. Handset Receive Frequency Response
Receive frequency response is the ratio of the sound pressure measured in the ear simulator to the
voltage input to the reference codec, or digital bit stream equivalent, for each frequency or frequency
band (Fi) as shown in the equation below:
SJE = 20 log (PE / VRCV) dB rel 1 Pa / V
Equation [2]
Where
SJE
PE
Receive Sensitivity, Junction to Ear, at Fi.
ERP Sound pressure measured by ear simulator at Fi. Measurement data are
converted from the Drum Reference Point (DRP) to the ERP.
RMS Input voltage to the reference codec or digital bit stream equivalent at Fi.
VRCV
6.1.2.1.
Measurement Method
The receive frequency response shall be measured with the receiver at the high leak position. The
receive frequency response is measured using the measurement set-up shown in Figure 5. Direct
digital processing may be employed as explained in clause 4.13. Measurements should be done in
1/12th octave bands or R40 intervals over a minimum range of 100 Hz through 4000 Hz. The test
signal level shall be -18.2 dBV (-16 dBm0), or digital bit stream equivalent.
Figure 5 – Handset Receive Frequency Response Measurement Method
Receive p
E Ear
Simulator
Decoder
Digital
Sound Pressure
Measuring
Amplifier
Interface
Set
Coder
vRCV
Quiet Room
6.1.2.2.
GEN
Reference Codec
Requirement
The receive frequency response requirements between 200 Hz and 4000 Hz (referenced to the ERP)
are as follows:
1. With the receiver at the high leak position, the receive frequency response:
a. Shall fall within the mandatory limits in Table 4 (shown in Figure 6).
b. Should fall within the desired limits in Table 4 (shown in Figure 6).
The limit curves shall be determined by straight lines joining successive co-ordinates given in the
table, where frequency response is plotted on a linear dB scale against frequency on a logarithmic
scale.
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SP-3-4352-RV2 (to become ANSI/TIA-810-B)
Table 4 – Co-ordinates of Handset Receive Response Limits
Limit Curve
upper limit
lower limit
Frequency
(Hz)
200
400
800
1000
2000
4000
8000
<300
300
800
2000
2800
3000
3400
>3400
Mandatory Receive Response
Limit
(dB) [arbitrary level]
Desired Receive Response
Limit
(dB) [arbitrary level]
+4
+4
+13
--+13
-16
- infinity
-30
-5
---5
-7
-infinity
+4
--+4
+9
+9
-20
- infinity
-10
-4
-4
-2
-7
-infinity
Figure 6 – Handset Receive Frequency Response Mask
Desired Limits
Mandatory Limits
15
10
Arbitrary Level (dB)
5
0
-5
-10
-15
-20
100
1000
Frequency (Hz)
NOTE -The frequency response mask in Figure 6 is a floating or “best fit” mask.
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SP-3-4352-RV2 (to become ANSI/TIA-810-B)
Annex D provides additional tutorial material with respect to the nominal receive frequency response
characteristic to illustrate the design intent of the limits. Receive is not specified below 200 Hz, but
Annex D provides a ‘suggested’ nominal frequency response characteristic to complete the design
intent. See Annex D for the details on the derivation of the nominal frequency response
characteristics.
6.2. Handset Loudness Ratings and Receive Volume Control
6.2.1. Handset Send Loudness Rating (SLR)
The SLR is defined in Annex A.
6.2.1.1.
Measurement Method
The SLR shall be calculated from the send frequency response measurement (clause 6.1.1) using
equations [A1] and [A3] in Annex A and frequency bands 4 to 17, Table A.1.
6.2.1.2.
Requirement
The terminal shall be designed to have a nominal SLR value of 8 dB, with a tolerance of ±4.0 dB.
6.2.2. Handset Receive Loudness Rating (RLR)
The RLR is defined in Annex A.
6.2.2.1.
Measurement Method
The RLR shall be calculated from the receive frequency response measurement (clause 6.1.2) using
equations [A1] and [A4] in Annex A and frequency bands 4 to 17, Table A.1.
6.2.2.2.
Requirement
The RLR values measured with the receiver at the high leak position shall have an RLR value of 2
dB, with a tolerance of -4.0/+8.0 dB and should have a nominal RLR value of 2 dB, with a tolerance
of ±4.0 dB.
6.2.3. Handset Receive Volume Control Range
The current regulatory volume control requirements are specified in 47 CFR Part 68.317.
NOTE - The RLR measurements in this document use a HATS (Head and Torso Simulator)
while the current 47 CFR Part 68.317 references ROLR measurements in ANSI/EIA/TIA579-1991, which specifies the Type 1 ear (ITU-T Recommendation P.57).
6.2.3.1.
Measurement Method
The RLR shall be calculated from the receive frequency response measured with the receiver at the
low leak position. The measurement shall be done with the volume control at either the Reference
Volume Control Setting, or the manufacturer’s defined reference volume control setting, and the
maximum setting. Use equations [A1] and [A4] in Annex A and frequency bands 4 to 17, Table A.1.
Measure the receive distortion and noise (see clause 6.5.2.1) with a 1004 Hz sinewave at -16 dBm0
input at the maximum volume control setting.
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SP-3-4352-RV2 (to become ANSI/TIA-810-B)
6.2.3.2.
Requirement
The RLR values measured with the receiver at the low leak position shall have a nominal RLR value
of 2 dB, with a tolerance of ±4.0 dB at the Reference Volume Control Setting or the manufacturer’s
defined reference volume control setting.
With the receiver at the low leak position the RLR at the maximum volume control setting shall be at
least 12 dB louder than the RLR at the Reference Volume Control Setting, or the manufacturer
defined reference volume setting (also measured at the low leak position). If the RLR at the
maximum volume control setting is more than 18 dB louder than the RLR at the Reference Volume
Control Setting or the manufacturer’s defined reference volume setting, then the CPE shall
automatically reset to either, the Nominal Volume Control Setting, the Reference Volume Control
Setting, or the manufacturer’s defined reference volume setting, after ending the call.
To ensure that there is no significant clipping, the receive signal to total distortion and noise ratio at
the maximum volume control setting shall be greater than 20 dB with a 1004 Hz, -16 dBm0 input.
(See clause 6.5.2 for test method.)
NOTE - Some special purpose CPE provide high receive gain for hearing impaired users.
These CPE are intended to provide the highest gain for below normal input signal levels, and
they might fail the distortion requirement at the maximum volume control setting when
measured with the specified test signal level.
6.2.4. Magnetic Field for Hearing Aid Coupling
This standard does not contain Magnetic Field for Hearing Aid Coupling requirements. The current
regulatory hearing aid compatibility magnetic output requirements are specified in 47 CFR Part
68.316.
NOTE - Part 68.316 does not provide suitable references for testing Digital Telephones.
Suitable test procedures are available in TSB-31-C, Part 68 Rationale and Measurement
Guidelines for US Network Protection.
6.2.5. Handset Talker Sidetone (STMR)
The sidetone masking rating (STMR) is defined in Annex A.
6.2.5.1.
Measurement Method
The test signal level at the MRP shall be -4.7 dBPa. For each frequency given in Table A.1, bands 1
to 20, the sound pressure in the ear simulator shall be measured. The STMR shall be calculated using
equation [A5] of Annex A.
Telephone sets with adjustable receive levels shall be tested at the minimum, nominal and maximum
settings.
6.2.5.2.
Requirement
The value of STMR shall be within the range of 18 dB ± 6 dB, for any adjustable receive level.
NOTE - In practice, sidetone measurements in the high leak position are limited to a value of
approximately 24 dB by the influence of the test setup (HATS).
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SP-3-4352-RV2 (to become ANSI/TIA-810-B)
6.2.6. Handset Sidetone Delay
In a digital telephone, sidetone echo occurs when significant delay is introduced into the speech path
between the handset microphone and the handset receiver by the sidetone feedback algorithm.
Ideally, the sidetone signal should be a real-time signal. Sidetone delay less than 5 ms is generally
perceived as normal sidetone. Sidetone delay between 5 and 10 ms is generally perceived as
unnatural sidetone, with an uncomfortable hollow characteristic. Sidetone delay greater than 10 ms is
generally perceived as a distinct talker echo signal. Since the sidetone level could be as loud, or
louder than a talker echo signal, sidetone delay greater than 5 ms is undesirable.
6.2.6.1.
Measurement Method
See the method described in IEEE Std 269.
6.2.6.2.
Requirement
Sidetone delay shall be less than 5 ms.
6.3. Handset Noise
6.3.1. Handset Send Noise
6.3.1.1.
General
The send noise of a digital telephone is the 5 second average noise level at the digital transmit output
with the telephone transmitter isolated from sound input and mechanical disturbances.
6.3.1.2.
Measurement Method
In a quiet environment (ambient noise less than 30 dBA), free of mechanical disturbances, measure
the noise level at the digital interface output or the reference codec decoder output over the
frequency range of 100 to 3400 Hz with apparatus that includes psophometric weighting, according
to ITU-T Recommendation 0.41.
6.3.1.3.
Requirement
The send noise shall be less than -68 dBm0p.
6.3.2. Handset Send Single Frequency Interference
6.3.2.1.
General
Narrowband noise, including single frequency interference, is an impairment that can be perceived as
a tone depending on its level relative to the overall weighted noise level. This test measures the
weighted noise level characteristics in narrow bands of not more than 31 Hz.
6.3.2.2.
Measurement Method
In a quiet environment (ambient noise less than 30 dBA), free of mechanical disturbances, measure
the psophometrically-weighted noise level at VSEND with a selective voltmeter or spectrum analyzer
with an effective bandwidth of not more than 31 Hz, over the frequency range of 100 to 3400 Hz. If
FFT analysis is used, then “Flat Top” windowing shall be employed.
6.3.2.3.
Requirement
The send single frequency interference shall be less than -78 dBm0p.
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SP-3-4352-RV2 (to become ANSI/TIA-810-B)
6.3.3. Handset Receive Noise
6.3.3.1.
General
The receive noise of a digital telephone is the 5 second average noise level measured at the output of
the telephone receiver with the digital telephone receiving the digital quiet code.
6.3.3.2.
Measurement Method
A signal corresponding to a decoder value quiet code is applied at the digital interface. The Aweighted noise level is measured in the ear simulator over the frequency range of 100 to 8500 Hz.
The ambient noise for this measurement shall not exceed 30 dBA.
6.3.3.3.
Requirement
The receive noise shall be less than 40 dBA.
6.3.4. Handset Receive Single Frequency Interference
6.3.4.1.
General
Narrowband noise, including single frequency interference, is an impairment that can be perceived as
a tone depending on its level relative to the overall weighted noise level. This test measures the
weighted noise level characteristics in narrow bands of not more than 31 Hz, which can then be
compared to the overall weighted receive noise level. Narrowband noise is measured at the output of
the telephone receiver with the digital telephone receiving the digital quiet code.
6.3.4.2.
Measurement Method
A signal corresponding to a decoder quiet code is applied at the digital interface. The A-weighted
noise level is measured in the ear simulator with a selective voltmeter or spectrum analyzer, with an
effective bandwidth of not more then 31 Hz, over the frequency range of 100 to 8500 Hz. If FFT
analysis is used, then “Flat Top” windowing shall be employed. The ambient noise for this
measurement shall not exceed 30 dBA.
6.3.4.3.
Requirement
The receive single frequency interference shall be 10 dB quieter than the A-weighted receive noise,
or below 30 dBA, whichever is less.
6.4. Handset Receive Comfort Noise (Advisory)
If comfort noise is introduced to replace actual background noise the level should roughly match the
loudness of the original background noise. There is more likely to be annoyance if the comfort noise
is greater than the original noise than if it is less.
6.4.1. General
The receive comfort noise of a digital telephone is the short-term average receive noise level
measured at the output of the telephone receiver with the terminal receiving either a silence
indication packet or no packets for some non-transient period of time.
6.4.2. Measurement Method
The digital interface is sent the quiet code  the code that represents silence for the coder format.
Disable comfort noise generation and any echo canceller on the terminal. Apply a white noise test
signal to the terminal and adjust the signal amplitude such that the receive noise level measured at
the terminal is 48 dBA. The test signal level is assigned the level of ‘N dB’. Enable comfort noise
generation on the terminal.
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SP-3-4352-RV2 (to become ANSI/TIA-810-B)
The following test sequence must be followed for test noise levels of ‘M dB’, which will range from
N-10 to N+10 dB.
1. The digital interface is sent the quiet code for 10 seconds.
2. Apply 300-3400 Hz band-limited white noise of level M dB to the terminal for 60 seconds.
3. Stop sending data to the terminal; this should cause the comfort noise generator to trigger and
apply comfort noise to the terminal receiver. Wait 10 seconds.
4. During the next 10 seconds the acoustic noise level at the receiver is measured.
5. Steps 1-4 are repeated for varying M in 5 dB increments.
6.4.3. Requirement
For a test signal level of M = N, verify that the measured receive noise level is 48 dBA +0.5/-3.0.
For all input noise levels M in the range of N-10 to N+10 the receive noise level measured must be
within +0.5/-3.0 dB of the expected receive noise level for that input. The expected receive noise
level for any given M and N is 48 dBA - (N-M).
6.5. Handset Distortion and Noise
The distortion and noise requirements only apply to G.711 codecs in mu-law. For systems that
cannot support G.711 see clause 5.
6.5.1. Handset Send Distortion and Noise
6.5.1.1.
Method of Measurement
Apply a sinewave signal at the MRP, with the levels given in Table 5 and the following frequencies:
315, 502, 803 and 1004 Hz. The ratio of the signal-to-total distortion and noise power of the digitally
encoded signal output is measured.
NOTE - In cases where the sound pressure exceeds +6 dBPa, the linearity of the mouth
simulator should be checked, as it exceeds the limits of ITU-T Recommendation P.51.
Table 5 – Handset Send Signal-to-Total Distortion and Noise Ratio Limits
Send level at the MRP
(dBPa)
Send Ratio
(dB)
-30
-24
-17
-10
0
+4
+8
+10
20
25
31
31
31
31
24
20
19
Send Ratio
(%)
10.0
5.6
2.8
2.8
2.8
2.8
6.3
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SP-3-4352-RV2 (to become ANSI/TIA-810-B)
6.5.1.2.
Requirement
The ratio of signal-to-total distortion and noise (SDN) of the digitally encoded signal output shall be
above the limits given in Table 5, with psophometric weighting applied to the measured distortion
and noise output. Limits for intermediate levels are found by drawing straight lines between the
breaking points in the table on a linear (dB signal level) versus linear (dB ratio) scale.
6.5.2. Handset Receive Distortion and Noise
6.5.2.1.
Method of Measurement
Apply a digitally simulated sinewave, with the levels given in Table 6 and the following frequencies:
315, 502, 803 and 1004 Hz. The ratio of signal-to-total distortion and noise power is measured with
the ear simulator.
6.5.2.2.
Requirement
The ratio of signal-to-total distortion and noise (SDN) measured with the ear simulator shall be above
the mandatory limits in Table 6, with A-weighting applied to the measured distortion and noise
output, and should be above the desired limits in Table 6, unless the signal in the ear simulator
exceeds +10 dBPa or is less than -50 dBPa.
Table 6 – Handset Receive Signal-to-Total Distortion and Noise Ratio Limits
Receive
level
at the
digital
interface
(dBm0)
-40
-34
-27
-20
-10
-6
-3
0
Desired
Receive
Ratio
at 315 Hz
(dB)
Desired
Receive
Ratio
at 315 Hz
(%)
Desired
Receive
Ratio
at 502, 803
1004 Hz
(dB)
Desired
Receive
Ratio
at 502, 803
1004 Hz
(%)
19
24
26
26
26
26
26
23
11.2
6.3
5.0
5.0
5.0
5.0
5.0
7.0
20
25
26
26
26
26
26
24
10.0
5.6
5.0
5.0
5.0
5.0
5.0
6.3
Mandatory Mandatory
Receive
Receive
Ratio
Ratio
at 1004 Hz at 1004 Hz
(dB)
(%)
n/a
n/a
n/a
26
26
26
26
24
n/a
n/a
n/a
5.0
5.0
5.0
5.0
6.3
6.6. Weighted Terminal Coupling Loss (TCLw)
The weighted terminal coupling loss (TCLw) provides a measure of the echo performance under
normal conversation, i.e., single far-end talker conditions. It is possible that echo control devices
such as echo suppressors or echo cancellers with non-linear processing may be used on handset
connections to provide sufficient echo return loss to mitigate increased echo associated with longer
network delays.
The use of echo control devices on the handset can affect the measurement of TCLw. The result
would likely be different under cases of either single far-end talker or double-talk. The TCLw
measurement is intended to represent a single far-end talker. This may provide idealized and
unrealistic performance measurements when non-linear processing on the transmit side is used as
part of the echo control algorithm. It may be more appropriate to measure TCLw either with non20
SP-3-4352-RV2 (to become ANSI/TIA-810-B)
linear processing disabled or with a near-end signal present that is a) capable of enabling echo
control’s double-talk detector with the subsequent removal of non-linear processing and b) can be
filtered out from the final return signal so as not to affect the accuracy of the TCLw measurement.
The latter may be the only method that can be used consistently across products in a black-box
testing setup. A suitable signal may be a pulsed sine wave, but it will depend on the temporal
characteristics of the double-talk detector.
The ‘proper’ measurement of TCLw then becomes specific to the echo control implementation.
These issues are still under study and are not addressed in these requirements. For further
information see IEEE Std 269.
6.6.1. Measurement Method
TCLw shall be measured with the handset receiver at the high leak Standard Test Position on the
HATS. The TCLw measurement shall be made at an input signal level of -16 and -10 dBm0.
The test should be performed in a quiet environment (the ambient noise level shall be less than
30 dBA.)
The test signal may be a composite source signal (CSS) as defined in ITU-T P.501 or bursted white
noise or bursted pink noise. The test signal shall be band-limited to 100 through 4000 Hz. The
calibration shall be determined during the ON portions of the signal. The measurement shall be
performed after system stability is reached (including convergence of any echo algorithms); this shall
be accomplished by invoking the test signal for at least 2 seconds before the actual measurement
occurs.
The attenuation from digital input to digital output is measured in 1/12 th octave bands, or R40
intervals for frequencies from 300 to 3150 Hz, using the measurement arrangement shown in
Figure 7. See Annex C.
The weighted terminal coupling loss is calculated according to ITU-T Recommendation G.122
(1993) Annex B, Section B.4 (trapezoidal rule).
Figure 7 – Terminal Coupling Loss Measurement Method
vSEND (Echo Return)
Ear
Simulator
Decoder
v
Coder
GEN
Digital
Set
Interface
vRCV
Anechoic Chamber
Reference Codec
6.6.2. Requirements
The normalized value of TCLw at the high leak position shall be greater than 52 dB for IP sets and
45 dB for PCM sets for at least one of the stimulus signal levels with SLR normalized to 8 dB and
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SP-3-4352-RV2 (to become ANSI/TIA-810-B)
RLR normalized to 2 dB. It is desirable that the normalized value of TCLw for IP sets be greater than
55 dB and that the normalized value of TCLw for PCM sets be greater than 50 dB to meet ITU-T
Recommendation G.131 talker echo objective requirements.
For example, if the measured TCLw is 48 dB, the measured SLR is 11 dB and the measured RLR is
0 dB, then the normalized value of TCLw = 48 dB + (8 - 11) dB + (2 - 0) dB = 47 dB.
NOTES
1. The requirement of 52 dB for IP sets is a function of the -16 dBm0 test signal level and
the -68 dBm0p send noise requirement. Measuring TCLw > 52 dB can be difficult.
2. If equipped with adjustable receive level, the un-normalized TCLw will decrease in
proportion with the increased gain relative to the nominal RLR in most cases. For
example, if the measured TCLw is 45 dB at nominal RLR and the adjustable receive level
adds 12 dB of gain, then un-normalized TCLw (maximum receive level) = 45 dB - 12 dB
= 33 dB. However, it is generally preferable that IP sets maintain 52 dB TCLw regardless
of the receive volume control gain.
3. The echo impairment perceived by the person at the opposite end of the connection
from a telephone set is a function of the magnitude of the talker echo signal as well as the
talker echo path delay. The echo signal becomes more disturbing as the talker echo path
delay increases. Thus, a telephone set with adequate TCLw performance on low delay
connections may provide satisfactory performance while the same may not be true for
connections that have a long delay.
4. Temporally weighted terminal coupling loss (TCLt) is an alternate method for echo
measurement, which may be more subjectively relevant, especially in devices with echo
suppression or cancellation features. (See IEEE Std 1329.) The performance requirements
may need to be changed when using this method. This issue is currently under study.
6.7. Stability Loss
The stability loss is a measure of the contribution of the telephone set to the overall network stability
requirements. Stability loss is defined as the minimum loss from the digital input (receive) to the
digital output (send), at any test frequency.
6.7.1. Measurement Method
The stability measurement shall be made at input signal levels of -16 and -10 dBm0. The test signal
may be CSS or bursted white noise or bursted pink noise, band-limited to 100 through 4000 Hz. The
measurement and calibration shall be determined during the ON portions of the signal. Sine wave
signals may be used with G.711 codecs. With the handset and transmission circuit fully active,
measure the attenuation from the digital input to the digital output using Method 1 and Method 2. See
Annex C.
6.7.1.1.
Method 1
Place the handset in the reference corner, as shown in Figure 8, with the earcap and mouthpiece
facing a hard, smooth surface. The handset shall be placed along the diagonal from the apex of the
reference corner to the outside corner, with the earcap end of the handset 250 mm from the apex. The
telephone set shall be fully active.
The reference corner consists of three perpendicular plane, smooth, hard surfaces extending 0.5 m
from the apex of the corner.
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SP-3-4352-RV2 (to become ANSI/TIA-810-B)
6.7.1.2.
Method 2
Place the handset with the earcap and mouthpiece facing a hard, smooth surface free of any other
object for 50 cm. The telephone set shall be fully active.
6.7.2. Requirement
Stability loss using both method 1 and method 2, (i.e., minimum loss, at any frequency) shall be
greater than 6 dB. It is desirable that this loss be greater than 10 dB.
Telephone sets with adjustable receive level should maintain stability over the entire range of
adjustable receive levels.
Figure 8 – Reference Corner
25 cm
50 cm
6.8. Long Duration Maximum Acoustic Pressure (Steady State Input)
6.8.1. General
The long duration maximum acoustic pressure is the steady state (longer than 500 ms) sound pressure
disturbance emitted from a handset receiver, caused by the maximum excursions of the receive
digital signal.
Additional consideration should be given to the acoustic pressure caused by tones, other audio
signals or long duration, high amplitude electrical signals applied to power, network, handset or
auxiliary leads of the digital telephone.
6.8.2. Measurement Method
The steady-state A-weighted sound pressure level shall be measured using the digital terminals test
procedure in IEEE Std 269 .
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6.8.3. Requirements
The measured maximum rms level shall be less than 125 dB(A).
NOTE - Required in UL 60950-2003.
6.9. Short Duration Maximum Acoustic Pressure (Peak)
6.9.1. General
The short duration maximum acoustic pressure is the sound pressure impulse (less than 500 ms)
emitted from a handset receiver.
This short duration test stresses nonlinear processes, like AGC, and doesn’t directly replace a short
duration surge. Additional consideration should be given to the peak acoustic pressure caused by
tones or short duration, high amplitude electrical pulses applied to power, network, handset or
auxiliary leads of the digital telephone.
6.9.2. Measurement Method
The peak acoustic pressure level shall be measured using the digital terminals test procedure in IEEE
Std 269.
6.9.3. Requirements
The maximum peak acoustic pressure shall be less than 136 dBSPL.
NOTE - Required in UL 60950-2003.
6.10.
VoIP Telephone Delay
Delay is a complex end-to-end issue. Certain aspects of delay can be optimized in VoIP telephones,
such as the internal hardware/firmware delay and the optimization of the jitter buffer operation,
which must trade-off the impairment of packet loss against the expected delay variation of the farend telephone and/or the network. Other aspects, such as packetization and depacketization are also
important sources of delay, but they are a function of the selected codec and the number of speech
frames per packet, so they cannot be optimized in VoIP telephones. Therefore, this standard now
specifies delay in terms of categories for network planning purposes, similar to ITU-T Rec. P.1010.
When reporting compliance with this standard, only the category with the largest measured delay
shall be reported, if the send and receive categories are different. If codecs or speech frame rates
other than those specified in the measurement methods are used, then they must be clearly identified
when reporting compliance.
6.10.1. Requirement
The wired terminals shall be configurable so that requirements of at least Category B are met.
Wireless terminals should be configurable so that the requirements of at least Category C are met.
6.10.2. Handset Send Delay
6.10.2.1.
General
The send delay is defined here as the time from when an acoustic signal leaves the mouth simulator
playing into a VoIP telephone’s handset to the time its digitized, packetized representation arrives at
that telephone’s packet network interface.
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SP-3-4352-RV2 (to become ANSI/TIA-810-B)
6.10.2.2.
Measurement Method
A digital audio measuring device capable of measuring the delay between an injected signal (to the
mouth simulator) and a digitally transmitted signal should be connected to the mouth simulator and
directly to the network output of the telephone. All delays inherent in the measurement system itself
must be calibrated out. The telephone should be set to transmit G.711 packets with a speech frame
rate of 20 ms and with one speech frame per packet.
An acoustic signal of -4.7 dBPa shall be generated at the mouth simulator. The delay between the
time the pulse left the mouth to the time it was received at the telephone’s packet network interface
shall be measured. The send delay shall be used to determine the corresponding category.




Category A: Ts ≤ 25 ms
Category B: Ts ≤ 35 ms
Category C: Ts ≤ 50 ms
Category D: Ts > 50 ms
6.10.3. Handset Receive Delay
6.10.3.1.
General
The receive delay is defined here as the time from when a digitized, packetized representation of a
signal arrives at that VoIP telephone’s packet network interface to the time its analog reproduction is
received at an ear simulator sealed to that telephone’s handset.
The handset receive delay requirements include the depacketization, hardware/firmware processing
and de-jitter delays, plus any delay associated with the radio link for wireless products.
6.10.3.2.
Measurement Method
A digital audio measuring device capable of measuring the delay between an injected digital packet
signal and the output of an ear simulator should be connected to the packet network input of the
telephone and to the ear simulator. All delays inherent in the measurement system itself must be
calibrated out. The telephone should be set to receive G.711 packets with a speech frame rate of 20
ms and with one speech frame per packet.
A pulsed digital signal of -16 dBm0 shall be injected as packets to the telephone’s network interface
without test signal jitter. The delay between the time that the packet was injected at the telephone
network interface to the time it was received at the ear simulator shall be measured. The receive
delay shall be used to determine the corresponding category.




Category A: Tr ≤ 30 ms
Category B: Tr ≤ 65 ms
Category C: Tr ≤ 100 ms
Category D: Tr > 100 ms
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7. Headset Technical Requirements
All tests shall be performed with a Type 3.3 ear simulator with the headset in the HATS position.
The headset is mounted as specified by IEEE Std 269. The Type 3.3 ear simulator shall comply with
the specifications given in ITU-T Recommendation P.57 (11/2005). The Type 3.3 shall have a
hardness of 35 ±6 degrees Shore-OO, as measured according to ASTM 2240. (ITU-T
Recommendation P.57 (07/2002) originally specified a hardness of 55 ±10 degrees Shore-OO for
Type 3.3.)
All tests shall be performed with the receive volume control set to the nominal volume control
setting, unless otherwise specified. Treatment of multiple volume controls is addressed in IEEE Std
269.
7.1. Headset Frequency Response
7.1.1. Headset Send Frequency Response
The send frequency response is the overall response of the transducer, send amplifier, and the codec
send filter. It is the ratio of the voltage output of the reference codec to the sound pressure at the
Mouth Reference Point for each frequency or frequency band (Fi). See Equation 1. The send
sensitivity is expressed in terms of dB (V/Pa).
7.1.1.1.
Measurement Method
The send frequency response is measured according to IEEE Std 269 using the measurement set-up
shown in Figure 3, substituting the handset with the headset. Measurements should be done in ISO
1/12th octave bands or R40 intervals, over a minimum range of 100 Hz through 4000 Hz. The test
signal level shall be -4.7 dBPa at the MRP.
7.1.1.2.
Requirement
The send frequency response shall fall between the upper and lower limits given in Table 7 and
shown in Figure 9. The limit curves shall be determined by straight lines joining successive coordinates given in the table, where frequency response is plotted on a linear dB scale against
frequency on a logarithmic scale.
Table 7 – Co-ordinates of Headset Send Response Limits
Limit Curve
upper limit
lower limit
Frequency
(Hz)
Send Response Limit
(dB) [arbitrary level]
200
1000
2000
3400
4000
300
300
1000
3000
3400
3400
+3
+3
+8
+8
3
- infinity
-9
-3
-3
-7
-infinity
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SP-3-4352-RV2 (to become ANSI/TIA-810-B)
Figure 9 – Headset Send Frequency Response Mask
15
10
Arbitrary Level (dB)
5
0
-5
-10
-15
-20
100
1000
10000
Frequency (Hz)
NOTE - The frequency response mask in Figure 9 is a floating or “best fit” mask.
7.1.2. Headset Receive Frequency Response
The receive frequency response is the overall response of the codec receive filter, receive amplifier
and transducer. It is the ratio of the sound pressure measured in the ear simulator to the voltage input
to the reference codec, or digital bit stream equivalent, for each frequency or frequency band (Fi).
See Equation 2. The receive sensitivity is expressed in terms of dB (Pa/V).
7.1.2.1.
Measurement Method
The receive frequency response is measured according to IEEE Std 269 using the measurement setup shown in Figure 5, substituting the handset with the headset. Both the left and right channels of
binaural (dual mono) headsets must be measured. Measurements should be done in ISO 1/12th octave
bands or R40 intervals, over a minimum range of 100 Hz through 4000 Hz. The test signal level shall
be -18.2 dBV (-16 dBm0), or digital bit stream equivalent. The frequency response measured with
the ear simulator must be transformed to the ear reference point (ERP).
7.1.2.2.
Requirement
The receive frequency response, including both the left and right channels of binaural headsets, shall
fall between the upper and lower limits given in Table 8 and shown in Figure 10. The limit curves
shall be determined by straight lines joining successive co-ordinates given in the table, where
frequency response is plotted on a linear dB scale against frequency on a logarithmic scale.
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SP-3-4352-RV2 (to become ANSI/TIA-810-B)
Table 8 – Co-ordinates of Headset Receive Response Limits
Limit Curve
Frequency
(Hz)
Receive Response Limit
(dB) [arbitrary level]
200
1000
2000
4000
8000
300
300
800
2000
2800
3400
3400
4
4
9
9
-20
- infinity
-10
-4
-4
-2
-7
-infinity
upper limit
lower limit
Figure 10 – Headset Receive Frequency Response Mask
15
10
Arbitrary Level (dB)
5
0
-5
-10
-15
-20
100
1000
Frequency (Hz)
NOTE - The frequency response mask in Figure 10 is a floating or “best fit” mask.
7.2. Headset Loudness Ratings
7.2.1. Headset Send Loudness Rating (SLR)
The SLR is defined in Annex A.
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SP-3-4352-RV2 (to become ANSI/TIA-810-B)
7.2.1.1.
Measurement Method
The SLR shall be calculated from the send frequency response measurement (clause 7.1.1) using
equations [A1] and [A3] in Annex A and frequency bands 4 to 17, Table A.1.
7.2.1.2.
Requirement
The terminal shall be designed to have a nominal SLR value of 10 dB, with a tolerance of ±5.0 dB.
NOTE - People tend to talk louder on a headset relative to a handset.
7.2.2. Headset Receive Loudness Rating (RLR)
The RLR is defined in Annex A.
7.2.2.1.
Measurement Method
The RLR shall be calculated from the receive frequency response measurement (clause 7.1.2) using
equations [A1] and [A4] in Annex A and frequency bands 4 to 17, Table A.1.
7.2.2.2.
Requirement
The monaural terminal shall have a nominal RLR value of 0 dB, with a tolerance of ±4.0 dB. The
binaural terminal shall have a nominal RLR value of 6 dB, with a tolerance of ±4.0 dB, for each of
the left and right channels measured separately.
NOTES:
1. Headset RLRs are louder than handset RLRs to compensate for lack of noise occlusion.
2. Either the terminal or the headset should have a receive volume control that is capable of
amplification and attenuation.
7.2.3. Headset Talker Sidetone (STMR)
The sidetone masking rating (STMR) is defined in Annex A.
7.2.3.1.
Measurement Method
The test signal level at the MRP shall be -4.7 dBPa. For each frequency given in Table A.1, bands 1
to 20, the sound pressure in the ear simulator shall be measured. The STMR shall be calculated using
equation [A5] of Annex A.
Telephone sets with adjustable receive levels shall be tested at the minimum, nominal and maximum
settings.
7.2.3.2.
Requirement
For any receive volume control setting, the value of STMR shall be within the range of 21 dB ± 6 dB
for supraural, 18 dB ± 6 dB for insert, 20 dB ± 6 dB for interconchial (ear bud). The value of STMR
for binaural terminals should be 6 dB quieter, for each of the left and right channels measured
separately.
NOTE - In practice, sidetone measurements in the high leak position are limited to a value of
approximately 24 dB by the influence of the test setup (HATS).
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SP-3-4352-RV2 (to become ANSI/TIA-810-B)
7.3. Headset Noise
7.3.1. Headset Send Noise
7.3.1.1.
General
The send noise of a digital headset telephone is the 5 second average noise level, at the digital
transmit output, with the headset transmitter isolated from sound input and mechanical disturbances.
7.3.1.2.
Measurement Method
In a quiet environment (ambient noise less than 30 dBA), free of mechanical disturbances, measure
the noise level at the digital interface output or the reference codec decoder output over the
frequency range of 100 to 3400 Hz with apparatus that includes psophometric weighting, according
to ITU-T Recommendation 0.41.
7.3.1.3.
Requirement
The send noise shall be less than -64 dBm0p.
7.3.2. Headset Send Single Frequency Interference
7.3.2.1.
General
Narrowband noise, including single frequency interference, is an impairment that can be perceived as
a tone depending on its level relative to the overall weighted noise level. This test measures the
weighted noise level characteristics in narrow bands of not more than 31 Hz.
7.3.2.2.
Measurement Method
In a quiet environment (ambient noise less than 30 dBA), free of mechanical disturbances, measure
the psophometrically-weighted noise level at VSEND with a selective voltmeter or spectrum analyzer
with an effective bandwidth of not more than 31 Hz, over the frequency range of 100 to 3400 Hz. If
FFT analysis is used, then “Flat Top” windowing shall be employed.
7.3.2.3.
Requirement
The send single frequency interference shall be less than -74 dBm0p.
7.3.3. Headset Receive Noise
7.3.3.1.
General
The receive noise of a digital telephone is the 5 second average noise level measured at the output of
the headset receiver with the digital telephone receiving the digital quiet code.
7.3.3.2.
Measurement Method
A signal corresponding to a decoder quiet code is applied at the digital interface. The A-weighted
noise level is measured in the ear simulator over the frequency range of 100 to 8500 Hz. The ambient
noise for this measurement shall not exceed 30 dBA.
7.3.3.3.
Requirement
The receive noise shall be less than 40 dBA for a monaural headset. The receive noise for binaural
headsets should be less than 34 dBA, for each of the receivers measured separately.
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SP-3-4352-RV2 (to become ANSI/TIA-810-B)
7.3.4. Headset Receive Single Frequency Interference
7.3.4.1.
General
Narrowband noise, including single frequency interference, is an impairment that can be perceived as
a tone depending on its level relative to the overall weighted noise level. This test measures the
weighted noise level characteristics in narrow bands of not more than 31 Hz, which can then be
compared to the overall weighted receive noise level. Narrowband noise is measured at the output of
the headset receiver with the digital telephone receiving the digital quiet code.
7.3.4.2.
Measurement Method
A signal corresponding to a decoder quiet code is applied at the digital interface. The A-weighted
noise level is measured in the ear simulator with a selective voltmeter or spectrum analyzer, with an
effective bandwidth of not more then 31 Hz, over the frequency range of 100 to 8500 Hz. If FFT
analysis is used, then “Flat Top” windowing shall be employed. The ambient noise for this
measurement shall not exceed 30 dBA.
7.3.4.3.
Requirement
The receive single frequency interference shall be 10 dB quieter than the A-weighted receive noise,
or below 30 dBA, whichever is less.
7.4. Headset Distortion and Noise
The distortion and noise requirements only apply to G.711 codecs in mu-law. For systems that
cannot support G.711 see clause 5.
7.4.1. Headset Send Distortion and Noise
7.4.1.1.
Method of Measurement
The distortion and noise is measured according to IEEE Std 269. Apply a sine wave signal at the
MRP, with the levels given in Table 9 and the following frequencies: 315, 502, 803 and 1004 Hz.
The ratio of the signal-to-total distortion and noise power of the digitally encoded signal output is
measured.
NOTE - In cases where the sound pressure exceeds +6 dBPa, the linearity of the mouth
simulator should be checked, as it exceeds the limits of ITU-T Recommendation P.51.
Table 9 – Headset Send Signal-to-Total Distortion and Noise Ratio Limits
Send level at the MRP
(dBPa)
Send Ratio
(dB)
Send Ratio
(%)
-30
-24
-17
-10
0
+4
+8
+10
20
25
31
31
31
31
24
20
10.0
5.6
2.8
2.8
2.8
2.8
6.3
10.0
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SP-3-4352-RV2 (to become ANSI/TIA-810-B)
7.4.1.2.
Requirement
The ratio of signal-to-total distortion and noise (SDN) of the digitally encoded signal output shall be
above the limits given in Table 9, with psophometric weighting applied to the measured distortion
and noise output. Limits for intermediate levels are found by drawing straight lines between the
breaking points in the table on a linear (dB signal level) - linear (dB ratio) scale.
7.4.2. Headset Receive Distortion and Noise
7.4.2.1.
Method of Measurement
The distortion and noise is measured according to IEEE Std 269. Both the left and right channels of
binaural headsets must be measured. Apply a digitally simulated sinewave, with the levels given in
Table 10 and the following frequencies: 315, 502, 803 and 1004 Hz. The ratio of signal-to-total
distortion and noise power is measured in the ear simulator.
7.4.2.2.
Requirement
The ratio of signal-to-total distortion and noise (SDN) measured with the ear simulator, including
both the left and right channels of binaural headsets, shall be above the limits given in Table 10, with
A-weighting applied to the measured distortion and noise output, unless the signal in the ear
simulator exceeds +10 dBPa or is less than -50 dBPa.
Table 10 – Headset Receive Signal-to-Total Distortion and Noise Ratio Limits
Receive level at
the digital
interface
(dBm0)
Receive Ratio
@ 315 Hz
(dB)
Receive Ratio
@ 315 Hz
(%)
Receive Ratio
@ 502, 803 and
1004 Hz
(dB)
Receive Ratio
@ 502, 803 and
1004 Hz
(%)
-34
-27
-20
-10
-6
-3
0
20
24
26
26
26
22
18
10.0
6.3
5.0
5.0
5.0
7.9
12.6
22
26
26
26
26
24
22
7.9
5.0
5.0
5.0
5.0
6.3
7.9
7.5. Weighted Terminal Coupling Loss (TCLw)
The weighted terminal coupling loss (TCLw) provides a measure of the echo performance under
normal conversation.
7.5.1. Measurement Method
TCLw is measured with the headset mounted on HATS, as described in IEEE Std 269. The TCLw
measurement shall be made at an input signal level of -16 and -10 dBm0.
The test should be performed in a quiet environment (the ambient noise level shall be less than 30
dBA.)
The test signal may be a composite source signal (CSS) as defined in ITU-T P.501 or bursted white
noise or bursted pink noise. The test signal shall be band-limited to 100 through 4000 Hz. The
calibration shall be determined during the ON portions of the signal. The measurement shall be
32
SP-3-4352-RV2 (to become ANSI/TIA-810-B)
performed after system stability is reached (including convergence of any echo algorithms); this shall
be accomplished by invoking the test signal for at least 2 seconds before the actual measurement
occurs.
The attenuation from digital input to digital output is measured in 1/12th octave bands, or R40
intervals for frequencies from 300 to 3150 Hz, using the measurement arrangement shown in Figure
11. See Annex C.
The weighted terminal coupling loss is calculated according to ITU-T Recommendation G.122
(1993) Annex B, Section B.4 (trapezoidal rule).
Figure 11 – Terminal Coupling Loss Measurement Method
Headset Mounted on HATS
vSEND (Echo Return)
Digital
Set
Decoder
v
Coder
GEN
Interface
Anechoic Chamber
Reference Codec
v RCV
Headset Mounted on HATS
vSEND (Echo Return)
v
Decoder
Digital
Set
Interface
Coder
GEN
vRCV
Anechoic Chamber
Reference Codec
7.5.2. Requirements
The normalized value of TCLw loss shall be greater than 52 dB for VoIP systems and 45 dB for
PCM telephone systems when measured on HATS and with SLR normalized to 10 dB and RLR
normalized to 0 dB. It is desirable that the normalized value of TCLw for IP sets be greater than
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SP-3-4352-RV2 (to become ANSI/TIA-810-B)
55 dB and that the normalized value of TCLw for PCM sets be greater than 50 dB to meet ITU-T
Recommendation G.131 talker echo objective requirements.
For binaural headsets, use the worst case RLR for calculating the normalized TCLw.
For example, if the measured TCLw is 48 dB, the measured SLR is 11 dB and the measured RLR is
-2 dB, then the normalized value of TCLw = 48 dB + (10 - 11) dB + [0 - (-2)] dB = 49 dB.
NOTES
1. If equipped with adjustable receive level, the un-normalized TCLw will decrease in
proportion with the increased gain relative to the nominal RLR in most cases. For
example, if the measured TCLw is 45 dB at nominal RLR and the adjustable receive level
adds 12 dB of gain, then un-normalized TCLw (maximum receive level) = 45 dB - 12 dB
= 33 dB.
2. The echo impairment perceived by the person at the opposite end of the connection
from a telephone set is a function of the magnitude of the talker echo signal as well as the
talker echo path delay. The echo signal becomes more disturbing as the talker echo path
delay increases. Thus, a telephone set with adequate TCLw performance on low delay
connections may provide satisfactory performance while the same may not be true for
connections that have a long delay.
3. Temporally weighted terminal coupling loss (TCLt) is an alternate method for echo
measurement, which may be more subjectively relevant, especially in devices with echo
suppression or cancellation features. (See IEEE Std 1329.) The performance requirements
may need to be changed when using this method. This issue is currently under study.
7.6. Long Duration Maximum Acoustic Pressure (Steady State Input)
7.6.1. General
The long duration maximum acoustic pressure is the steady state (longer than 500 ms) sound pressure
disturbance emitted from a headset receiver, caused by the maximum excursions of the receive
digital signal.
Additional consideration should be given to the acoustic pressure caused by tones, other audio
signals or long duration, high amplitude electrical signals applied to power, network, headset or
auxiliary leads of the digital telephone.
7.6.2. Measurement Method
The steady-state A-weighted sound pressure level shall be measured using the digital terminals test
procedure in IEEE Std 269.
7.6.3. Requirements
The measured maximum rms level shall be less than 118 dB(A).
NOTE - Required in UL 60950-2003.
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SP-3-4352-RV2 (to become ANSI/TIA-810-B)
7.7. Short Duration (Peak) Acoustic Pressure
7.7.1. General
The short duration maximum acoustic pressure is the sound pressure impulse (less than 500 ms)
emitted from a headset receiver.
This short duration test stresses nonlinear processes, like AGC, and doesn’t directly replace a short
duration surge. Additional consideration should be given to the peak acoustic pressure caused by
tones or short duration, high amplitude electrical pulses applied to power, network, handset or
auxiliary leads of the digital telephone.
7.7.2. Measurement Method
The peak acoustic pressure level shall be measured using the digital terminals test procedure in IEEE
Std 269.
7.7.3. Requirements
The maximum peak acoustic pressure shall be less than 136 dBSPL.
NOTE - Required in UL 60950-2003.
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SP-3-4352-RV2 (to become ANSI/TIA-810-B)
8. Handsfree Technical Requirements
The handsfree test methods are given in IEEE Std 1329.
Traditional tabletop or desktop handsfree telephones shall be measured using the standard 30 x 40 x
50 cm test position defined in IEEE Std 1329. Handheld handsfree telephones shall be measured in
free-air on axis at 50 cm from the front of the phone. The mouth simulator and free field microphone
shall be aligned from the center of the phone’s visual display.
Handsfree telephones designed for specialized applications should be tested with the appropriate user
positioning in mind. This position shall be defined as the “recommended test position” (RTP). The
RTP should be obtained from the manufacturer, and should be based upon the product’s intended
use. For testing purposes, this will dictate the distance and position geometry between the handsfree
telephone, the mouth simulator and the free field microphone.
All tests shall be preformed with the receive volume control set to the nominal volume control
setting, unless otherwise specified.
NOTE - that the nominal volume control setting in this standard is the reference volume
control (RVC) setting defined in IEEE Std 1329.
8.1. Handsfree Frequency Response
8.1.1. Handsfree Send Frequency Response
The send frequency response is the overall response of the transducer, send amplifier, and the codec
send filter. It is the ratio of the voltage output of the reference codec to the sound pressure at the
Mouth Reference Point for each frequency or frequency band (Fi). See Equation 1. The send
sensitivity is expressed in terms of dB(V/Pa).
8.1.1.1.
Measurement Method
The send frequency response is measured in or converted to 1/3rd octave bands, according to IEEE
Std 1329, over a minimum range of 100 Hz through 4000 Hz. For desktop handsfree use the
measurement set-up shown in Figure 12. For other handsfree devices see the comments in clause 8.
The nominal test signal level shall be -4.7 dBPa at the MRP.
Figure 12 – Handsfree Send Frequency Response Measurement Method
vSEND
Mouth Simulator
Send
GEN
Decoder
pM
Measuring
Amplifier
Interface
50 cm
v
30 cm
Coder
40 cm
Anechoic Chamber
Digital
Set
(On Table)
Reference Codec
8.1.1.2.
Requirement
The send frequency response shall fall between the 1/3rd octave band upper and lower limits given in
Table 11 and shown in Figure 13.
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Table 11 – Co-ordinates of Handsfree Send Response Limits
Limit Curve
1/3rd Octave
Band (Hz)
Send Response Limit
(dB) [arbitrary level]
upper limit
100
125
160 to 1000
1250
1600
2000 to 3150
4000
250
315
400
500
630
800
1000 to 2500
3150
4000
-3.5
+0.5
+3.5
+5.5
+7.5
+8.5
+3.5
- infinity
-9.5
-8.5
-7.5
-6.5
-5.5
-3.5
-6.5
-infinity
lower limit
Figure 13 – Handsfree Send Frequency Response Mask
15
10
Arbitrary Level (dB)
5
0
-5
-10
-15
-20
100
1000
Frequency (Hz)
NOTE - The frequency response mask in Figure 13 is a floating or “best fit” mask.
37
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SP-3-4352-RV2 (to become ANSI/TIA-810-B)
8.1.2. Handsfree Receive Frequency Response
The receive frequency response is the overall response of the codec receive filter, receive amplifier
and transducer. It is the ratio of the sound pressure measured at the 50TP position to the voltage input
to the reference codec, or digital bit stream equivalent, for each frequency or frequency band (Fi).
See Equation 2. The receive sensitivity is expressed in terms of dB(Pa/V).
8.1.2.1.
Measurement Method
The receive frequency response is measured in or converted to 1/3 rd octave bands, according to IEEE
Std 1329, over a minimum range of 100 Hz through 4000 Hz. For desktop handsfree use the
measurement set-up shown in Figure 14. For other handsfree devices see the comments in clause 8.
The test signal level shall be -25 dBV (-22.8 dBm0), or digital bit stream equivalent.
Figure 14 – Handsfree Receive Frequency Response Measurement Method
To Sound Pressure
Measuring Amplifier
Decoder
Free Field Microphone
Receive pE
Interface
50 cm
30 cm
40 cm
Anechoic Chamber
GEN
Coder
Digital
Set
(On Table)
vRCV
Reference Codec
8.1.2.2.
Requirement
The receive frequency response shall fall between the 1/3rd octave band upper and lower limits given
in Table 12 and shown in Figure 15.
Table 12 – Co-ordinates of Handsfree Receive Response Limit Curves
Limit Curve
1/3rd Octave
Band (Hz)
Receive Response Limit
(dB) [arbitrary level]
upper limit
100
125
160
200 to 4000
5000
6300
8000
250
315
400
500 to 2500
3150
4000
-4
-1
+2
+5
-2
-9
-20
- infinity
-7
-6
-5
-8
-infinity
lower limit
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SP-3-4352-RV2 (to become ANSI/TIA-810-B)
Figure 15 – Handsfree Receive Frequency Response Mask
15
10
Arbitrary Level (dB)
5
0
-5
-10
-15
-20
100
1000
10000
Frequency (Hz)
NOTE - The frequency response mask in Figure 15 is a floating or “best fit” mask.
8.2. Handsfree Loudness Ratings and Receive Volume Control
Correlation factors relating handsfree loudness ratings to handset loudness ratings are used in this
standard. The currently accepted correlation factors for personal, wireline telephone applications are
shown below. These correlation factors may not be appropriate for other handsfree applications such
as conference, hand-held, in-car applications or any applications where the relationship between the
talker and the handsfree varies from the 50 cm position, or the reverberation characteristics or the
background noise levels vary from typical office environments.
The handsfree SLR should be 5 dB quieter than the handset SLR due to:



a 3 dB increase in the average talking level when using a handsfree,
a 1-2 dB decrease in the actual handset talking levels compared to those measured at the MRP,
other small differences related to different frequency responses, etc.
Subjective evaluations have determined that the handsfree RLR should be 14 dB quieter than the
handset RLR. The RLR calculation in Annex A corrects for this, see equation [A6].
8.2.1. Handsfree Send Loudness Rating (SLR)
The SLR is defined in Annex A.
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SP-3-4352-RV2 (to become ANSI/TIA-810-B)
8.2.1.1.
Measurement Method
The SLR shall be calculated from the send frequency response measurement 1/3 rd octave sensitivity
data (clause 8.1.1) using equation [A3] in Annex A and frequency bands 4 to 17, Table A.1.
8.2.1.2.
Requirement
The terminal shall be designed to have a nominal handsfree SLR value of 13 dB, with a tolerance of
±4.0 dB.
8.2.2. Handsfree Receive Loudness Rating (RLR)
The RLR is defined in Annex A.
8.2.2.1.
Measurement Method
The RLR shall be calculated from the receive frequency response measurement 1/3 rd octave
sensitivity data (clause 8.1.2) using equation [A6] in Annex A and frequency bands 4 to 17,
Table A.1.
8.2.2.2.
Requirement
The terminal shall be designed to have a nominal handsfree RLR = 2 dB, with a tolerance of ±4.0 dB.
8.2.3. Handsfree Receive Volume Control
8.2.3.1.
Measurement Method
Measure the RLR at each volume control setting.
8.2.3.2.
Requirement
The handsfree receive volume control shall provide greater than or equal to 8 dB of gain relative to
the nominal volume control setting. The volume control should provide at least 16 dB of attenuation
relative to the nominal volume control setting. The volume control step size shall be less than 6 dB.
8.3. Handsfree Noise
8.3.1. Handsfree Send Noise
8.3.1.1.
General
The send noise of a digital telephone is the 5 second average noise level, at the digital transmit
output, with the microphone isolated from sound input and mechanical disturbances.
8.3.1.2.
Measurement Method
With the handsfree terminal in a quiet environment (ambient noise less than 30 dBA), free of
mechanical disturbances, measure the noise level at the digital interface output or the reference codec
decoder output over the frequency range of 100 to 3400 Hz with apparatus that includes
psophometric weighting according to ITU-T Recommendation 0.41.
8.3.1.3.
Requirement
The handsfree send noise shall be less than -64 dBm0p.
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SP-3-4352-RV2 (to become ANSI/TIA-810-B)
8.3.2. Handsfree Send Single Frequency Interference
8.3.2.1.
General
Narrowband noise, including single frequency interference, is an impairment that can be perceived as
a tone depending on its level relative to the overall weighted noise level. This test measures the
weighted noise level characteristics in narrow bands of not more than 31 Hz.
8.3.2.2.
Measurement Method
In a quiet environment (ambient noise less than 30 dBA), free of mechanical disturbances, measure
the psophometrically-weighted noise level at VSEND with a selective voltmeter or spectrum analyzer
with an effective bandwidth of not more than 31 Hz, over the frequency range of 100 to 3400 Hz. If
FFT analysis is used, then “Flat Top” windowing shall be employed.
8.3.2.3.
Requirement
The handsfree send single frequency interference shall be less than -74 dBm0p.
8.3.3. Handsfree Receive Noise
8.3.3.1.
General
The receive noise of a digital handsfree telephone is the 5 second average noise level measured at the
50TP position with the digital telephone receiving the digital quiet code.
8.3.3.2.
Measurement Method
Comfort noise generation shall be disabled. A signal corresponding to a decoder value quiet code is
applied at the digital interface. The A-weighted noise level is measured over the frequency range of
100 to 8500 Hz at both the nominal and maximum volume control settings. The ambient noise for
this measurement shall not exceed 30 dBA.
8.3.3.3.
Requirement
The handsfree receive noise shall be less than 40 dBA at the maximum volume control setting and
less than 35 dBA with the volume control at the nominal volume control setting, with the comfort
noise turned off.
8.3.4. Handsfree Receive Single Frequency Interference
8.3.4.1.
General
Narrowband noise, including single frequency interference, is an impairment that can be perceived as
a tone depending on its level relative to the overall weighted noise level. This test measures the
weighted noise level characteristics in narrow bands of not more than 31 Hz, which can then be
compared to the overall weighted receive noise level. Narrowband noise is measured at the output of
the handsfree speaker at 50TP position with the digital telephone receiving the digital quiet code.
8.3.4.2.
Measurement Method
A signal corresponding to a decoder quiet code is applied at the digital interface. The A-weighted
noise level is measured with a selective voltmeter or spectrum analyzer, with an effective bandwidth
of not more then 31 Hz, over the frequency range of 100 to 8500 Hz. If FFT analysis is used, then
“Flat Top” windowing shall be employed. The ambient noise for this measurement shall not exceed
30 dBA.
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SP-3-4352-RV2 (to become ANSI/TIA-810-B)
8.3.4.3.
Requirement
The handsfree receive single frequency interference shall be 10 dB quieter than the A-weighted
receive noise, or below 30 dBA at nominal and maximum volume control settings, whichever is less.
8.4. Handsfree Distortion and Noise
The distortion and noise requirements only apply to G.711 codecs in mu-law. For systems that
cannot support G.711 see clause 5
8.4.1. Handsfree Send Distortion and Noise
8.4.1.1.
Method of Measurement
Apply a test signal at the MRP, with the levels given in Table 13 and the following frequencies: 502,
803 and 1004 Hz. The ratio of the signal-to-total distortion and noise power of the digitally encoded
signal output is measured.
NOTE - In cases where the sound pressure exceeds +6 dBPa, the linearity of the mouth
simulator should be checked, as it exceeds the limits of ITU-T Recommendation P.51.
8.4.1.2.
Requirement
The ratio of signal-to-total distortion and noise (SDN) of the digitally encoded signal output shall be
above the limits given in Table 13, with psophometric weighting applied to the measured distortion
and noise output. Limits for intermediate levels are found by drawing straight lines between the
breaking points in the table on a linear (dB signal level) - linear (dB ratio) scale.
NOTE - An erroneous test result for the SDN measurement may occur if the amplitude of the
frequency response curve at the test frequency is at a high or low peak which is significantly
different from a smoothed curve approximation. An example of this is provided in Annex E.
If this occurs, alternate test point frequencies or test methods should be utilized. IEEE Std
269 and IEEE Std 1329 provide additional information regarding alternate distortion
measurement methods. Also ITU Recommendation O.131 may be considered.
Table 13 – Handsfree Send Signal-to-Total Distortion and Noise Ratio Limits
Send level at the MRP
(dBPa)
Send Ratio
(dB)
Send Ratio
(%)
-12
-8
-4
0
+4
+8
18
30
31
31
31
24
12.6
3.2
2.8
2.8
2.8
6.3
8.4.2. Handsfree Receive Distortion and Noise
8.4.2.1.
Method of Measurement
Apply a digitally simulated test signal, with the levels given in Table 14 and the following
frequencies: 502, 803 and 1004 Hz. The ratio of signal-to-total distortion and noise power is
measured at the 50TP point.
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SP-3-4352-RV2 (to become ANSI/TIA-810-B)
8.4.2.2.
Requirement
The measured ratio of signal-to-total distortion and noise (SDN) shall be above the limits given in
Table 14, with A-weighting applied to the measured distortion and noise output, unless the measured
sound pressure is less than -50 dBPa. The measurement microphone may be placed at 25 cm for this
measurement if the measured signal levels are too low.
NOTE - An erroneous test result for the SDN measurement may occur if the amplitude of the
frequency response curve at the test frequency is at a high or low peak which is significantly
different from a smoothed curve approximation. An example of this is provided in Annex E.
If this occurs, alternate test point frequencies or test methods should be utilized. IEEE Std
269 and IEEE Std 1329 provide additional information regarding alternate distortion
measurement methods. Also ITU Recommendation O.131 may be considered.
Table 14 – Handsfree Receive Signal-to-Total Distortion and Noise Ratio Limits
Receive level at the
digital interface
(dBm0)
Receive Ratio
Receive Ratio
(dB)
(%)
-34
-27
-20
-10
-6
-3
25
26
26
26
26
23
5.6
5.0
5.0
5.0
5.0
7.0
8.5. Weighted Terminal Coupling Loss (TCLw)
The weighted terminal coupling loss (TCLw) provides a measure of the echo performance under
single talk conditions.
8.5.1. Measurement Method
Refer to IEEE Std 1329 for the test method.
8.5.2. Requirements
The normalized value of handsfree TCLw loss shall be greater than 50 dB when measured under free
field conditions and with SLR normalized to 13 dB and RLR normalized to 2 dB. It is desirable that
the normalized value of TCLw be greater than 53 dB to meet ITU-T Recommendation G.131 talker
echo objective requirements.
NOTE - Generally the handsfree send-path idle noise is higher than the handset send-path
idle noise and this masks echo.
For example, if the measured handsfree TCLw is 27 dB, the measured SLR is 16 dB and the
measured RLR is 1 dB, then the normalized value of TCLw = 27 dB + (13 - 16) dB + (2 - 1) dB
= 25 dB.
NOTE - Temporally weighted terminal coupling loss (TCLt) is an alternate method for echo
measurement, which may be more subjectively relevant, especially in devices with echo
43
SP-3-4352-RV2 (to become ANSI/TIA-810-B)
suppression or cancellation features. (See IEEE Std 1329.) The performance requirements
may need to be changed when using this method. This issue is currently under study.
8.6. Stability Loss
The stability loss is a measure of the telephone set's contribution to the overall network stability
requirements. Stability loss is defined as the minimum loss from the digital input (receive) to the
digital output (send), at any test frequency.
8.6.1. Measurement Method
Place the handsfree telephone in the middle of a hard, smooth surface free of any other object for
0.5 m. The telephone set shall be fully active. The surface must be at least 1 square meter.
The stability measurement shall be made at input signal levels of -16 and -10 dBm0. The test signal is
CSS or bursted white noise, band-limited to 100 through 4000 Hz. With the handsfree and
transmission circuit fully active, measure the attenuation from the digital input to the digital output.
8.6.2. Requirement
The handsfree stability loss, i.e., minimum loss, at any frequency shall be greater than 6 dB and
should be greater than 10 dB.
Telephone sets with adjustable receive level should maintain stability over the entire range of
adjustable receive levels.
44
SP-3-4352-RV2 (to become ANSI/TIA-810-B)
Annex A (normative) – Calculation of Loudness Ratings
This Annex details the loudness rating calculations and weighting factors relevant to this document.
Loudness ratings are a measure of loudness loss and are used in network planning to insure that the
loudness of a connection from the Mouth Reference Point (MRP) of the talker to the Ear Reference
Point (ERP) of the far end listener is at a satisfactory level. The loudness loss of the complete path is
designated as the Overall objective Loudness Rating (OLR). The Send Loudness Rating (SLR) is the
loudness loss from the MRP to the electrical output. The Receive Loudness Rating (RLR) is the
loudness loss from the electrical input to the ERP. The Sidetone Masking Rating (STMR) is the
loudness loss from the MRP to the ERP via the electric sidetone path.
Loudness ratings are used rather than simple level measurements because of better subjective
correlation. Loudness ratings more closely account for the ear’s different sensitivity at different
frequencies and its nonlinear response to varying sound levels. The following calculations are based
on the 1993 and 1999 revisions of ITU-T Recommendation P.79. Older versions of P.79 should not
be used. ITU-T P.79 provides information on the derivation of the loudness rating algorithm.
For use in these loudness ratings formulae, frequency response measurements shall be converted to
the R10 format, by using band averaging according to equation [A1]. At each ISO R10 preferred
frequency:
1
H ( f )  10 log 10 
N
N
 10
i 1
Hi
10



Equation [A1]
Where:
H’(f)
f
N
i
Hi
= response at the new preferred ISO R10 frequency
= preferred ISO R10 frequency
= number of response values within the 1/3rd octave band centered at f
= index for each response value within the 1/3 rd octave band
= measured response value (in dB)
For the lowest frequency within the band, i = 1. For the highest included frequency, i = N.
The 1/3 rd octave pass band-limit frequencies can be calculated according as:
f  10( n /10)  0.05
Equation [A2]
Where n is the band number.
(Note that these band numbers, n, are not the same as the P.79 band numbers used in Table A.1.)
Send Loudness Rating:
SLR 
 10
log 10
0.175
N  Band17

 0.175
S MJ  Wsi 

10

10
Equation [A3]
i  Band 4
Where:
i
SMJ
Wsi
Frequency bands from Table 1 of ITU-T P.79-1999, bands 4-17.
Send Frequency response data (Sensitivity, Mouth-to-Junction) in dBV/Pa measured
per this standard.
Send weighting factor from Table 1 of ITU-T P.79-1999, see Table A.1.
45
SP-3-4352-RV2 (to become ANSI/TIA-810-B)
Receive Loudness Rating (Handset and Headset):
RLR 
 10
log 10
0.175
N  Band17

 0.175
S JE  Wri 

10

10
Equation [A4]
i  Band 4
Where:
i
SJE
Wri
Frequency bands from Table 1 of ITU-T P.79-1999, bands 4-17.
Receive frequency response data (Sensitivity, Junction-to-Ear) in dBPa/V measured
per this standard.
Receive weighting factor from Table 1 of ITU-T P.79-1999, see Table A.1.
Sidetone Masking Rating (Handset and Headset):
STMR 
 10
log 10
0.225
N  Band 20

 0.225
S meST  WMSi 

10

10
Equation [A5]
i  Band1
Where:
i
SmeST
WMSi
Frequency bands from Table 3 of ITU-T P.79-1999, bands 1-20.
Sidetone frequency response data (Sensitivity, mouth-to-ear) in dB Pa/Pa measured
per this standard.
Sidetone weighting factor from Table 3 of ITU-T P.79-1999, see Table A.1.
Receive Loudness Rating (Handsfree):

 0.175
S JE  Wri  

N  Band17

  10
10
   Corr
RLR  
log 10  10

RFF
i  Band 4
 0.175





Equation [A6]
Where:
i
SJE
Frequency bands from Table 1 of ITU-T P.79-1999, bands 4-17.
Receive frequency response data (Sensitivity, Junction-to-Ear) in dBPa/V measured
per this standard.
Wri
Receive weighting factor from Table 1 of ITU-T P.79-1999, see Table A.1.
Correction of 14 dB for receive measured in the free field as recommended
CorrRFF
in ITU-T P.340 (05/2000)
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SP-3-4352-RV2 (to become ANSI/TIA-810-B)
Table A.1 – ITU-T P.79-1999 Tables 1, 2 and 3
Weighting factors for calculating loudness ratings
Band No.
Midfrequency
(Hz)
Send
Wsi
Receive
Wri
Receive
LE
(dB)
Sidetone
WMSi
1
100
110.4
2
125
107.7
3
160
104.6
4
200
76.9
85.0
8.4
98.4
5
250
62.6
74.7
4.9
94.0
89.8
6
315
62.0
79.0
1.0
7
400
44.7
63.7
-0.7
84.8
8
500
53.1
73.5
-2.2
75.5
9
630
48.5
69.1
-2.6
66.0
68.0
-3.2
57.1
49.1
10
800
47.6
11
1000
50.1
68.7
-2.3
12
1250
59.1
75.1
-1.2
50.6
13
1600
56.7
70.4
-0.1
51.0
14
2000
72.2
81.4
3.6
51.9
51.3
15
2500
72.6
76.5
7.4
16
3150
89.2
93.3
6.7
50.6
17
4000
117.0
113.8
8.8
51.0
18
5000
49.7
19
6300
50.0
20
8000
52.8
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SP-3-4352-RV2 (to become ANSI/TIA-810-B)
Annex B (informative) – Measurement and Level Conversions
General
The following describes how to convert between various units of measurement used in telephone
testing.
Useful Conversions and Procedures
0 dBm (0 VU) is accepted as 1mW, typically using a circuit impedance of 600  or 900 .
0dBm = 10 log 1(mW)
dBV = 10 log V2
= 20 log V
or,
V = 10 dBV/20
P = V2/R, where for dBm reference, R = 600 
dBm = 10 log (V2/R * 1000)
= 10 log (V2/600 * 1000)
= 10 log (V2/0.600)
Therefore, for 0 dBm, V = 774.6 mV or 0 dBm = -2.218 dBV @ 600  (use -2.2 dB)
P = V2/R, where for dBm reference, R = 900 
dBm = 10 log (V2/R * 1000)
= 10 log (V2/900 * 1000)
= 10 log (V2/0.900)
Therefore, for 0 dBm, V = 948.7 mV or 0 dBm = -0.458 dBV @ 900  (use -0.5 dB)
This means that if we substitute 600  for 900  or vice versa, and the voltage remains constant,
then we have:
Correction (dB) = -10 log 0.600/0.900 = 10 log 0.900/0.600 = 1.761 dB
To simplify,
Correction (dB) = 10 log( |Z1| / |Z2| ), that is, the log of the ratio of the magnitude of the impedances,
when converting from impedance Z1 to Z2.
If converting from "Z1 = 600 " to "Z2 = 900 ", the correction factor is -1.76 dB (use -1.8 dB),
thus we subtract 1.8 dB from the measurement.
At this point, depending on the impedance being used, conversion factors can be applied dB for dB to
the measured or calculated result. As an example, to convert a 600  signal at -20dBm signal to
dBV, simply subtract 2.2 to get -22.2 dBV. Another example is if -20 dBm is measured across
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SP-3-4352-RV2 (to become ANSI/TIA-810-B)
600 , then across 900 , we add a correction of -1.8 dB to get -21.8 dBm (since less power is
dissipated by the higher resistance).
Acoustic Sound Pressure Conventions
dBPa (dB Pascals)
dBSPL (dB Sound Pressure Level)
Where,
0 dBPa = 94dBSPL, and 0 dBSPL = 20 microPascals, 1 Pa = 1 N/m2
An A weighted sound pressure level in dB (dBSPL, A weighted) is often abbreviated to “dBA”.
49
SP-3-4352-RV2 (to become ANSI/TIA-810-B)
Annex C (informative) – Preferred 1/12th Octave Frequencies
The ISO 3, R40 basic series preferred numbers, in terms of 1/12th octave frequencies are listed in
Table C.1. The frequencies highlighted in Italics are the R10, 1/3rd octave frequencies.
Table C.1 – Preferred 1/12th Octave Frequencies
#
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
Preferred Frequencies
(Hz)
#
100
106
112
118
125
132
140
150
160
170
180
190
200
212
224
236
250
265
280
300
315
335
355
375
400
425
450
475
500
530
560
600
630
670
710
750
800
850
900
950
1000
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
50
Preferred Frequencies
(Hz)
1000
1060
1120
1180
1250
1320
1400
1500
1600
1700
1800
1900
2000
2120
2240
2360
2500
2650
2800
3000
3150
3350
3550
3750
4000
4250
4500
4750
5000
5300
5600
6000
6300
6700
7100
7500
8000
8500
9000
9500
10000
SP-3-4352-RV2 (to become ANSI/TIA-810-B)
Annex D (informative) – Nominal Handset Frequency Response Derivation
Introduction
This Annex details the derivation of the handset frequency response requirements. The derivation
starts with the Mouth Reference Point (MRP) to the Eardrum Reference Point (DRP) information
that was used to derive the wideband weights for TIA-920 in Annex G of ITU-T Recommendation
P.79, as documented in ITU-T Delayed Contribution Com 12 No. D.65. Then a nominal MRP-to-Ear
Reference Point (ERP) response is derived because these are the send and receive test points used in
this Standard. A nominal send frequency response is created based on the response in Annex A of
TIA-579-A that was used for the transition from IEEE loudness ratings (LRs) to ITU-T LRs. Finally,
a nominal receive response is developed by subtracting the nominal send response from the MRP-toERP nominal response. Knowing the design intent of the nominal frequency responses is key to
understanding the specified frequency response limits.
The idea of measuring the end-to-end performance of telecommunication systems from the MRP-toDRP is not new. It had its genesis when the Type 3 ear simulator, as specified in ITU-T
Recommendation P.57 became a reality and it became possible to determine the performance of
telephone receivers with a measured leak, rather than the Type 1 Earphone Coupling Loss factor LE.
Use of the Type 3 ear has a number of advantages particularly for modern telephone handsets with
earpieces that do not seal perfectly to human ears and with the shift to low acoustic impedance
receivers.
Choice of Fundamental Reference System
If the Fundamental Reference System (FRS) is to be based on the 1 meter air path, then it makes
sense to base the actual responses on a standard that can, if required, be set up in laboratories.
Although the 1 meter air path is well documented, papers that reference it are based on old
technology that is unlikely to be reproducible in the 21st century. The most suitable current standard
upon which to base an FRS, is ITU-T Recommendation P.58, the Head And Torso Simulator
(HATS). As the Type 3 ear simulator specified in Recommendation P.57 is central to P.58, P.58
specifies responses in free field to the DRP and gives a correction factor (S DE) from the ERP-toDRP. This factor is essential to relate measurements made at the DRP to those made at ERP. At
present the loudness rating algorithm is based on data that originates from human ear studies using
the ERP and therefore any loudness rating calculations made on measurements at the DRP need to
include a correction to refer the result to the equivalent loudness at ERP.
Nominal HATS FRS End-to-End Frequency Response
With the choice made that the FRS will be based on the HATS, it is necessary to decide how the send
and receive parts will be characterized in order to achieve a sensible transition from earlier reference
systems. Figure D.1 shows the breakdown of the 1 meter air path from the MRP of a talker (HATS
send) to the DRP and ERP of a listener (HATS receive). Table D.1, Column 2, gives the free field
frequency response of HATS to the DRP and the explanation for this is given in Rec. P.58. Column 3
of Table D.1 gives the correction (SDE) from the DRP-to-ERP, taken from Rec. P.57 Table 2a. This
enables the free field response of the HATS at the ERP to be derived in Column 4 of Table D.1,
which is similar to the end-to-end response of the ARAEN System, which is approximated in Column
6 of Table D.1 from a curve in the “Handbook of Telephonometry”. The data in Table D.1 are plotted
in Figure D.2.
In ITU-T Delayed Contribution Com 12 No. D.34, an argument was given for breaking down the
send and receive parts of the ARAEN FRS such that all the pre-emphasis is assigned to the send part,
51
SP-3-4352-RV2 (to become ANSI/TIA-810-B)
SRMJ, and the receive part, SRJE, has essentially a flat sensitivity frequency characteristic, which is
opposite to the way it is presented for the ARAEN FRS in the “Handbook of Telephonometry”, but is
aligned with how it is actually done in telephones. The same arrangement is used in the ITU-T
Delayed Contribution Com 12 No. D.65 contribution, so that in effect the characteristic from the
MRP-to-ERP of the HATS (Column 4 of Table D.1) essentially becomes the characteristic of the
send part, SRMJ, for the “new” HATS FRS, and the receive part, SRJE, again has a flat sensitivity
frequency characteristic. This in turn means that the frequency characteristic of the receive part to the
DRP, SRJD, becomes the inverse of SDE and is given in Column 5 of Table D.1.
The assignment of the high frequency pre-emphasis to the send part has traditionally been used in
telephony to compensate for the high frequency attenuation due to capacitive coupling in the copper
wires connecting analog telephones to the end office. In addition, the primary goal of telephony is
intelligibility in a reduced bandwidth environment. This requires more high frequency content around
2800 Hz to make fricatives and stop consonants intelligible.
Figure D.1 – Fundamental Reference System Considerations
MRP
ERP
DRP
1 Meter
Metre air path
Junction
- SDE
(Table 1
Col. 3)
Reference
Path to ERP
Reference
Path to DRP
SRMJ
SRJE
(Flat response)
(Table 1 Column 4)
SRMJ
SRJD
(Table 1 Column 5)
(Table 1 Column 4)
Overall Reference Path
(Table 1 Column 2)
Figure 1
52
SP-3-4352-RV2 (to become ANSI/TIA-810-B)
Table D.1 – HATS Fundamental Reference System Responses plus ARAEN
Frequency
(Hz)
HATS Free
Field Response
to DRP
(dB)
SDE
(dB)
1
100
125
160
200
250
315
400
500
630
800
1000
1250
1600
2000
2500
3150
4000
5000
6300
8000
2
0
0
0
0
0.5
1.0
1.5
2.0
2.5
3.5
3.5
3.5
5.0
12.5
18.5
15.5
13.0
11.0
5.0
2.0
3
0
0
0
0
-0.3
-0.2
-0.5
-0.6
-0.7
-1.1
-1.7
-2.6
-4.2
-6.5
-9.4
-10.3
-6.6
-3.2
-3.3
-16.0
HATS FF
response to
ERP, equates to
SRMJ
(dB)
4
0
0
0
0
0.2
0.8
1.0
1.4
1.8
2.4
1.8
0.9
0.8
6.0
9.1
5.2
6.4
7.8
1.7
-14.0
SRJD
equates to
– SDE
(dB)
Approximate
ARAEN
End-to-End
Sensitivity
(dB)
5
0
0
0
0
0.3
0.2
0.5
0.6
0.7
1.1
1.7
2.6
4.2
6.5
9.4
10.3
6.6
3.2
3.3
16.0
6
0
0
0
0
0
0
0
0
0
0.6
1.0
1.5
2.8
5.0
6.5
8.5
8.5
6.0
0.4
-7.0
Notes:
1.
2.
3.
4.
Column 2 is from ITU-T Rec. P.58, Table 2.
Column 3 is from ITU-T Rec. P.57, Table 2a.
Column 4 equals the sum of Columns 2 and 3.
Columns 4 and 5 may be turned into electro-acoustic quantities by assuming that
1 Pa equates to 1 Volt at the electrical interfaces.
5. Column 6 is approximated from CCITT “Handbook on Telephonometry”, Figure
6/2.1
Assuming that a telephone has a flat receive frequency response in practice often has complications.
Two decades ago, handset earphones were large and they sealed well to both human ears and for test
purposes, to the ear simulator simulator in use at the time, referred to as the Type 1. The receivers in
those handsets had “high” acoustic impedance, meaning that they were designed to be used in a small
enclosed volume. Many modern handsets have reduced the size of the earpiece to the point where
they do not seal to human ears or ear simulator simulators. Therefore, the “high” acoustic impedance
receivers are being replaced with “low” acoustic impedance designs that can tolerate acoustic leaks
or even operate as speakers in free space. As well, modern ear simulator simulators have had to adapt
to simulate the human ear more accurately. However, different ear simulator simulators produce
different results, so this Standard recommends only the Type 3.3 simulator because it has a variable
force/distance handset positioner, a well defined ERP position and it is suitable for handset, headset
and handsfree measurements.
53
SP-3-4352-RV2 (to become ANSI/TIA-810-B)
Telephones with “high” acoustic impedance receivers that do not naturally seal to the Type 3.3
pinna, have a frequency response characteristic that is anything but flat, in fact it is called a
“haystack” response with a peak at about 1500 Hz. These receivers are labeled “leak intolerant”. This
Annex is focused on modern “leak tolerant” receivers.
Figure D.2 – HATS Fundamental Reference System Responses Vs. ARAEN
HATS FF-DRP [Col 2]
S DE [Col 3]
HATS FF-ERP[Col 4]
S RJD (S DE) [Col 5]
ARAEN [Col 6]
25
20
Arbitrary Level (dB)
15
10
5
0
-5
-10
-15
-20
100
1000
10000
Frequency (Hz)
Given the above preamble, the question remains: What is a practical nominal MRP-to-ERP
sensitivity response for the Type 3.3 HATS for telephones with leak tolerant receivers?
The red HATS Free Field-to-ERP (SRMJ) response curve in Figure D.2 appears to be inconsistent at
3150 Hz (Column 4 of Table D.1), where a “head bump” response consisting of a broad peak from
about 3 to 5 kHz, with an amplitude of 8 dB, relative to dc is expected. In addition, the Column 4
data has only third octave resolution, but twelfth octave resolution would be more useful for a
reference nominal with the understanding that in reality there may be considerable variation from this
reference nominal with humans and other ear simulators.
One way forward is to compare the HATS Free Field-to-ERP (SRMJ) response in Column 4 of Table
D.1 (the red curve in Figure D.2 and Figure D.2) with Brüel & Kjær’s generic HATS Free Field-toERP response in Column 2 of Table D.2 (the dark blue curve in Figure D.3). They are in close
agreement at most frequencies permitting the creation of a “nominal” MRP-to-ERP sensitivity
response for this Fundamental Reference System – the green curve in Figure D.3 and Column 3 of
Table D.2 plus 3 dB. The reason for the 3 dB correction is because these three curves are normalized
to 0 dB at low frequencies, but later it will be more convenient to normalize to 0 dB at 1000 Hz. To
simplify the subsequent send and receive responses, this HATS FRS nominal MRP-to-ERP
sensitivity response maintains a constant slope upwards from 200 to 1800 Hz even though the other
curves take a small dip between 1000 and 1600 Hz. Manufacturers may choose to use their expertise
to optimize the responses in this region.
54
SP-3-4352-RV2 (to become ANSI/TIA-810-B)
Figure D.3 – Derivation of HATS FRS Nominal MRP-to-ERP Sensitivity Response
HATS FF-ERP [A.1Col4]
B&K HATS Generic FF-ERP [A.2Col2]
FRS Nominal MRP-ERP [A.2Col3+3dB]
15
10
Arbitrary Level (dB)
5
0
-5
-10
-15
-20
100
1000
10000
Frequency (Hz)
Table D.2 – FRS Sensitivity Response Data
Frequency
(Hz)
B&K HATS
Generic FF-ERP
(dB)
FRS Nominal
MRP-ERP
(dB)
1
2
3
100
106
112
119
126
133
141
150
158
168
178
188
200
211
224
237
251
266
282
299
316
335
355
376
398
422
0.18
0.20
0.23
0.28
0.14
0.13
0.24
0.37
0.33
0.12
0.13
0.16
0.13
0.26
0.23
-0.07
-0.21
0.30
0.50
0.46
1.15
1.41
0.88
0.75
1.11
1.09
-3.00
-3.00
-3.00
-3.00
-3.00
-3.00
-3.00
-3.00
-3.00
-3.00
-3.00
-3.00
-3.00
-2.89
-2.79
-2.68
-2.57
-2.46
-2.36
-2.25
-2.14
-2.04
-1.93
-1.82
-1.71
-1.61
55
Narrowband
Nominal
MRP-ERP
(dB)
4
-34.61
-32.79
-30.42
-28.33
-26.26
-24.21
-22.20
-20.22
-18.31
-16.46
-14.70
-13.03
-11.46
-10.00
-8.65
-7.41
-6.35
-5.42
-4.56
-3.83
-3.16
-2.59
-2.14
-1.78
-1.51
-1.30
Wideband
Nominal
MRP-ERP
(dB)
5
-11.12
-9.79
-8.50
-7.37
-6.40
-5.76
-5.19
-4.69
-4.26
-3.89
-3.58
-3.33
-3.11
-2.94
-2.79
-2.68
-2.57
-2.46
-2.36
-2.25
-2.14
-2.04
-1.93
-1.82
-1.71
-1.61
SP-3-4352-RV2 (to become ANSI/TIA-810-B)
447
473
501
531
562
596
631
668
708
750
794
841
891
944
1000
1059
1122
1189
1259
1334
1413
1496
1585
1679
1778
1884
1995
2113
2239
2371
2512
2661
2818
2985
3162
3350
3548
3758
3981
4217
4467
4732
5012
5309
5623
5957
6310
6683
7079
7499
7943
1.37
2.79
2.15
1.48
1.81
2.40
2.04
2.39
1.99
2.00
3.56
3.75
3.32
4.29
3.76
2.60
3.00
3.02
1.81
2.01
2.62
1.89
2.26
2.04
3.72
3.78
4.89
5.32
5.44
6.19
8.07
7.07
6.89
7.28
6.96
7.42
7.47
8.35
8.17
8.18
7.38
8.48
8.19
8.10
7.75
6.18
5.56
2.92
1.52
-3.83
-13.45
-1.50
-1.39
-1.29
-1.18
-1.07
-0.96
-0.86
-0.75
-0.64
-0.54
-0.43
-0.32
-0.21
-0.11
0.00
0.08
0.17
0.25
0.33
0.42
0.50
0.58
0.67
0.80
1.00
1.40
2.00
2.50
3.10
3.70
4.20
4.60
4.80
4.85
4.90
4.95
5.00
5.00
5.00
5.00
4.90
4.80
4.65
4.40
3.90
3.00
1.00
-2.00
-6.00
-12.00
-20.00
-1.15
-1.03
-0.93
-0.86
-0.79
-0.73
-0.66
-0.60
-0.53
-0.46
-0.38
-0.29
-0.20
-0.10
0.00
0.08
0.17
0.25
0.33
0.42
0.50
0.58
0.67
0.80
1.00
1.40
2.00
2.50
3.10
3.70
4.20
4.60
4.80
4.83
3.59
-0.84
-10.34
-24.71
-42.09
-1.50
-1.39
-1.29
-1.18
-1.07
-0.96
-0.86
-0.75
-0.64
-0.54
-0.43
-0.32
-0.21
-0.11
0.00
0.08
0.17
0.25
0.33
0.42
0.50
0.58
0.67
0.80
1.00
1.40
2.00
2.50
3.10
3.70
4.20
4.57
4.82
5.05
5.27
5.46
5.60
5.71
5.80
5.64
5.47
5.23
4.92
4.56
4.10
3.58
2.28
-1.59
-10.03
-23.09
-39.37
While this HATS FRS has an ideal wideband characteristic, this Standard only specifies narrowband
digital telephone characteristics, so a narrowband characteristic was derived from the HATS FRS
characteristic with the -3 dB points at approximately 300 and 3400 Hz. The narrowband MRP-toERP objective is given in Table D.2, Column 4 and plotted in Figure D.4 as the blue curve. For
comparison, the FRS nominal MRP-to-ERP response is plotted in Figure D.4 as the green curve.
Similarly, the wideband digital telephone standard, TIA-920, only adds an extra upper and lower
octave relative to this Standard, so a preliminary, “reduced” wideband characteristic was derived
from the HATS FRS characteristic with the -3 dB points at approximately 200 and 6800 Hz for a
future revision of TIA-920. The wideband MRP-to-ERP objective is given in Table D.2, Column 5
and plotted in Figure D.4 as the red curve.
56
SP-3-4352-RV2 (to become ANSI/TIA-810-B)
Figure D.4 – Comparison of HATS FRS, Narrowband and Preliminary Wideband Nominal
MRP-to-ERP Sensitivity Responses
Narrowband Nom MRP-ERP [A.2Col4]
Wideband Nom MRP-ERP [A.2Col5]
FRS Nom MRP-ERP [A.2Col3]
10.00
Arbitrary Level (dB)
5.00
0.00
-5.00
-10.00
-15.00
-20.00
100
1000
10000
Frequency (Hz)
Nominal HATS FRS Send Frequency Response
Relatively minor changes to the send frequency response limits for digital sets have been made since
TIA-579-A was published in 1998. A flatter response in the mid-band (400-1000 Hz) and a reduced
high frequency pre-emphasis (about 3 dB lower at 2800 Hz) is encouraged in this Standard. These
changes reflect the transition from the previous priority of digital set-to-analog set calls to the new
priority of digital set-to-digital set calls, where there is no need to compensate for copper losses.
Figure 4 of this Standard is repeated here as Figure D.5 with the nominal response data in Table D.3
Column 2. It shows the send limits and the nominal send response. Since the send response defines
the narrowband bandwidth, the 300 and 3400 Hz points have been selected to be -3 dB relative to the
1000 Hz sensitivity. The pre-emphasis peak of 3 dB at 3000 Hz is suggested by both the upper and
lower limits. This narrowband nominal send response produces SLR = 8.0 dB @ -12.894 dBV/Pa @
1000 Hz.
The narrowband nominal and the corresponding limits are also repeated in Figure D.6 with the blue
curve and black limits. They are compared to the proposed preliminary wideband nominal frequency
response and corresponding limits for the next revision of TIA-920 with the green nominal curve and
the red limits. The wideband nominal send data is given in Table D.3 Column 3. Using the same
narrowband sensitivity of -12.894 dBV/Pa for this preliminary wideband nominal response, the
narrowband SLR = 7.5 dB while the wideband SLR = 3.0 dB.
57
SP-3-4352-RV2 (to become ANSI/TIA-810-B)
Figure D.5 – Narrowband Nominal Send Frequency Response and Limits
Mandatory Limits
Suggested Handset Send
Nominal Handset Send
15
10
Arbitrary Level (dB)
5
0
-5
-10
-15
-20
100
1000
10000
Frequency (Hz)
Figure D.6 – Comparison of Narrowband and Preliminary Wideband Nominal Send
Frequency Responses and Limits
TIA920A
TIA810B
TIA810B Suggested
TIA810B Nominal
TIA920A Nominal
15
10
Arbitrary Level (dB)
5
0
-5
-10
-15
-20
100
810B SLR = 8.0 @ -12.9 dBV/Pa
1000
Frequency (Hz)
58
920A NB SLR = 7.5 @ -12.9 dBV/Pa
920A WB SLR = 3.0 @ -12.9 dBV/Pa
10000
SP-3-4352-RV2 (to become ANSI/TIA-810-B)
Table D.3 – Send and Receive Frequency Response Data
Frequency
(Hz)
Narrowband
Nominal Send
(dB)
1
2
Preliminary
Wideband
Nominal Send
(dB)
3
100
106
112
119
126
133
141
150
158
168
178
188
200
211
224
237
251
266
282
299
316
335
355
376
398
422
447
473
501
531
562
596
631
668
708
750
794
841
891
944
1000
1059
1122
1189
1259
1334
1413
1496
1585
1679
1778
1884
1995
2113
2239
2371
2512
2661
2818
2985
-22.33
-21.54
-20.20
-19.13
-18.05
-16.97
-15.88
-14.78
-13.68
-12.58
-11.48
-10.38
-9.29
-8.22
-7.17
-6.16
-5.20
-4.32
-3.51
-2.81
-2.21
-1.73
-1.35
-1.07
-0.87
-0.73
-0.65
-0.60
-0.57
-0.55
-0.53
-0.52
-0.50
-0.48
-0.44
-0.40
-0.34
-0.28
-0.20
-0.11
0.00
0.12
0.25
0.39
0.55
0.72
0.90
1.09
1.29
1.50
1.72
1.95
2.18
2.40
2.62
2.82
3.00
3.16
3.27
3.33
-7.62
-6.79
-6.00
-5.27
-4.61
-4.02
-3.49
-3.04
-2.66
-2.35
-2.09
-1.88
-1.72
-1.59
-1.49
-1.42
-1.35
-1.30
-1.26
-1.23
-1.20
-1.17
-1.14
-1.11
-1.07
-1.04
-1.00
-0.96
-0.92
-0.87
-0.82
-0.76
-0.70
-0.63
-0.56
-0.48
-0.40
-0.31
-0.21
-0.11
0.00
0.12
0.24
0.37
0.51
0.65
0.81
0.97
1.14
1.32
1.51
1.70
1.91
2.11
2.33
2.54
2.76
2.97
3.17
3.35
59
Narrowband
Nominal Receive
(dB)
-12.28
-11.24
-10.21
-9.20
-8.21
-7.24
-6.32
-5.44
-4.63
-3.88
-3.22
-2.65
-2.17
-1.78
-1.48
-1.25
-1.15
-1.10
-1.05
-1.02
-0.95
-0.87
-0.79
-0.71
-0.64
-0.57
-0.50
-0.43
-0.37
-0.31
-0.26
-0.21
-0.16
-0.12
-0.09
-0.06
-0.03
-0.02
0.00
0.00
0.00
-0.03
-0.08
-0.14
-0.21
-0.30
-0.40
-0.51
-0.63
-0.70
-0.72
-0.55
-0.18
0.10
0.48
0.88
1.20
1.44
1.53
1.50
4
Preliminary
Wideband
Nominal Receive
(dB)
5
-3.40
-2.90
-2.40
-2.00
-1.69
-1.64
-1.59
-1.54
-1.49
-1.44
-1.39
-1.34
-1.29
-1.24
-1.19
-1.16
-1.12
-1.06
-0.99
-0.92
-0.85
-0.77
-0.69
-0.61
-0.54
-0.47
-0.40
-0.33
-0.27
-0.21
-0.16
-0.11
-0.06
-0.02
0.01
0.04
0.07
0.08
0.10
0.10
0.10
0.07
0.03
-0.02
-0.07
-0.14
-0.21
-0.29
-0.37
-0.42
-0.41
-0.20
0.19
0.49
0.87
1.26
1.54
1.70
1.75
1.80
SP-3-4352-RV2 (to become ANSI/TIA-810-B)
3162
3350
3548
3758
3981
4217
4467
4732
5012
5309
5623
5957
6310
6683
7079
7499
7943
2.39
-0.84
-6.34
-13.71
-22.09
3.52
3.66
3.75
3.81
3.80
3.74
3.62
3.43
3.17
2.86
2.50
2.08
1.08
-1.59
-6.03
-12.09
-19.37
1.20
0.00
-4.00
-11.00
-20.00
1.85
1.90
1.95
2.00
2.10
2.00
1.95
1.90
1.85
1.80
1.70
1.60
1.30
0.10
-3.90
-10.90
-19.90
Nominal HATS FRS Receive Frequency Response
As discussed earlier, significant changes have been made to receiver acoustic impedance, earpiece
design and ear simulator simulators over recent years. The main purpose of this Annex is to aid the
telephone set designer to design digital telephones with the correct receive frequency response and
sensitivity.
Knowing the desired narrowband nominal MRP-to-ERP response for the HATS FRS and the desired
nominal send response, the desired nominal receive response is simply the difference between the
two nominal responses. Figure 6 has been repeated here as Figure D.7 with the nominal response
data in Table D.3 Column 4. It shows the narrowband receive limits and the nominal frequency
response. The nominal response applies to the Desired Limits only. The purpose of the Mandatory
Limits is to Grandfather existing products and the intent is to remove the Mandatory Limits from the
next revision of this Standard.
The nominal response is essentially flat from 300 to 2000 Hz with a small amount of high frequency
boost around 2800 Hz for enhanced intelligibility, as suggested by both the upper and lower limits.
This narrowband nominal receive response produces RLR = 2.0 dB @ 8.66 dBPa/V @ 1000 Hz.
The narrowband receive nominal and the corresponding limits are also repeated in Figure D.8 with
the blue curve and black limits. They are compared to the proposed preliminary wideband nominal
frequency response and corresponding limits for the next revision of TIA-920 with the green nominal
curve and the red limits. The wideband nominal receive data is given in Table D.3 Column 5. Using
the same narrowband sensitivity of 8.66 dBPa/V for this wideband nominal response, the narrowband
RLR = 1.7 dB while the wideband RLR = -4.5 dB, without any correction factors.
60
SP-3-4352-RV2 (to become ANSI/TIA-810-B)
Figure D.7 – Narrowband Nominal Receive Frequency Response and Limits
Desired Limits
Mandatory Limits
Suggested Handset Receive
Nominal Handset Receive
15
10
Arbitrary Level (dB)
5
0
-5
-10
-15
-20
100
1000
10000
Frequency (Hz)
Figure D.8 – Comparison of Narrowband and Preliminary Wideband Nominal Receive
Frequency Responses and Limits
TIA920A
Desired TIA810B
Mandatory TIA810B
TIA920A Nominal
TIA810B Suggested
TIA810B Nominal
15
10
Arbitrary Level (dB)
5
0
-5
-10
-15
-20
100
1000
810B RLR = 2.0 @ 8.7 dBPa/V
Frequency (Hz)
61
920A NB RLR = 1.7 @ 8.7 dBPa/V
920A WB RLR = -4.5 @ 8.7 dBPa/V
10000
SP-3-4352-RV2 (to become ANSI/TIA-810-B)
Narrowband Summary
Figure D.9 summarizes the three narrowband nominal responses for this Standard: send plotted in
blue (Table D.3 Column 2), receive plotted in red (Table D.3 Column 4) and MRP-to-ERP plotted in
green (Table D.2 Column 4). The calculated narrowband loudness ratings are detailed in Table D.4.
Table D.4 – Narrowband Loudness Ratings
Freq Nom Tx Nom Rx Nom OLR
(Hz) (dBV/Pa) (dBPa/V)
(dB)
200
-22.14
6.49
-15.70
250
-18.18
7.50
-10.61
315
-15.14
7.71
-7.44
400
-13.75
8.03
-5.73
500
-13.46
8.29
-5.17
630
-13.40
8.50
-4.90
800
-13.23
8.63
-4.60
1000
-12.89
8.66
-4.24
1250
-12.37
8.45
-3.91
1600
-11.57
8.02
-3.55
2000
-10.71
8.50
-2.21
2500
-9.90
9.83
-0.08
3150
-10.37
9.88
-0.56
4000
-35.68
-11.53
-46.33
WS
WR
WO
76.9
85.0
66.1
62.6
74.7
60.7
62.0
79.0
68.5
44.7
63.7
55.6
53.1
73.5
66.9
48.5
69.1
63.3
47.6
68.0
63.4
50.1
68.7
65.3
59.1
75.1
73.1
56.7
70.4
70.1
72.2
81.4
82.0
72.6
76.5
78.6
89.2
93.3
95.4
117.0 113.8
76.9
Loudness Ratings ----->
SLR
(dB)
0.01848
0.03859
0.04467
0.09487
0.06842
0.08270
0.08619
0.07900
0.05615
0.06387
0.03541
0.03599
0.01809
0.00213
8.0
RLR
(dB)
0.04227
0.06668
0.05654
0.10610
0.07224
0.08698
0.09141
0.08898
0.06818
0.08098
0.05299
0.06812
0.03468
0.00641
2.0
OLR
(dB)
0.03703
0.05650
0.04689
0.08449
0.05479
0.06404
0.06456
0.06069
0.04490
0.05143
0.03359
0.04199
0.02092
0.00698
10.0
Figure D.9 – Narrowband Nominal Responses
TIA810B Nominal Send
TIA810B Nominal Receive
TIA810B Nominal MRP-ERP
10
Arbitrary Level (dB)
5
0
-5
-10
-15
-20
100
1000
Frequency (Hz)
0
62
10000
SP-3-4352-RV2 (to become ANSI/TIA-810-B)
Preliminary Wideband Summary
Figure D.9 summarizes the preliminary three wideband nominal responses for a future revision of the
TIA-920 standard: send plotted in blue (Table D.3 Column 3), receive plotted in red (Table D.3
Column 5) and MRP-to-ERP plotted in green (Table D.2 Column 5). The calculated preliminary
wideband loudness ratings are detailed in Table D.5, without any correction factors.
Table D.5 – Preliminary Wideband Loudness Ratings
Freq Nom Tx Nom Rx Nom OLR
(Hz) (dBV/Pa) (dBPa/V)
(dB)
100
-20.52
5.16
-15.36
125
-17.58
6.83
-10.76
160
-15.50
7.07
-8.43
200
-14.61
7.27
-7.35
250
-14.25
7.44
-6.82
315
-14.09
7.71
-6.39
400
-13.97
8.03
-5.94
500
-13.81
8.29
-5.53
630
-13.59
8.50
-5.09
800
-13.28
8.63
-4.65
1000
-12.89
8.66
-4.24
1250
-12.40
8.49
-3.91
1600
-11.72
8.18
-3.55
2000
-10.98
8.76
-2.21
2500
-10.16
10.08
-0.08
3150
-9.38
10.41
1.02
4000
-9.09
10.65
1.56
5000
-9.71
10.41
0.70
6300
-11.76
9.87
-1.92
8000
-33.22
-11.34
-44.24
WS
WR
WO
103.0 115.4 107.0
75.3
87.5
80.1
60.2
72.3
65.7
59.5
72.1
66.1
52.9
67.2
60.7
59.4
75.8
68.5
45.4
63.6
55.6
56.6
74.6
66.9
53.5
70.4
63.3
53.8
69.9
63.4
55.9
70.9
65.3
64.2
78.4
73.1
60.6
74.9
70.1
73.7
85.2
82.0
70.4
81.6
78.6
87.1
95.4
95.4
68.2
77.0
76.9
84.5
91.7
92.4
86.5
92.4
92.2
71.0
89.0
76.7
Loudness Ratings ----->
63
SLR
(dB)
0.00689
0.02369
0.04734
0.05048
0.06681
0.05175
0.09143
0.05858
0.06697
0.06701
0.06253
0.04565
0.05424
0.03297
0.03893
0.02049
0.04440
0.02246
0.01907
0.01500
3.0
RLR
(dB)
0.01177
0.03875
0.07220
0.07335
0.08998
0.06433
0.10652
0.06911
0.08255
0.08467
0.08143
0.05979
0.06797
0.04596
0.05603
0.03255
0.06901
0.03780
0.03595
0.01754
-4.5
OLR
(dB)
0.00722
0.02570
0.05043
0.05184
0.06584
0.04892
0.08376
0.05402
0.06355
0.06443
0.06069
0.04490
0.05143
0.03359
0.04199
0.02230
0.04803
0.02485
0.02254
0.00765
3.4
SP-3-4352-RV2 (to become ANSI/TIA-810-B)
Figure D.10 – Preliminary Wideband Nominal Responses
TIA920A Nominal Send
TIA920A Nominal Receive
TIA920A Nominal MRP-ERP
10
Arbitrary Level (dB)
5
0
-5
-10
-15
-20
100
1000
Frequency (Hz)
64
10000
SP-3-4352-RV2 (to become ANSI/TIA-810-B)
Annex E (informative) – SDN Erroneous Result Example
The ‘CPE SDNR Example’ is an actual Receive SDNR test result for a CPE that exhibited an
erroneous failure at a test frequency of 803 Hz due to high-Q characteristics in the frequency
response.
Table E.1 – SDN measurements (Erroneous Result)
Level
Spec
-34
-27
-20
-10
-6
-3
25
26
26
26
26
23
CPE SDNR
Example
803 Hz
3.6
10.8
18.3
23.3
24.0
25.7
Figure E.1 – Frequency Response Curve for SDN Erroneous Result
Speakerphone Recv - Frequency Response 12th Octave
CPE SDNR Example
5
dBV/Pa
0
-5
-10
-15
-20
100
1000
Frequency (Hz)
65
10000
SP-3-4352-RV2 (to become ANSI/TIA-810-B)
Annex F (informative) – Bibliography
The following documents contain useful information for understanding the basis for requirements
contained in this Standard. All documents are subject to revision and parties are encouraged to
investigate the possibility of applying the most recent editions of the documents indicated below.
ANSI/TIA-571-B-2006 Telecommunications - User Premises Equipment - Environmental
Considerations.
ANSI/EIA/TIA-579-1991, Acoustic-to-Digital and Digital-to-Acoustic Transmission Requirements
for ISDN Terminals.
ANSI/TIA/EIA-579-A-1998, Requirements for Digital Wireline Telephones.
ISO 3: 1973, Preferred numbers - Series of preferred numbers.
ITU-T Recommendation G.131 (11/2003), Talker echo and its control.
ITU-T Recommendation G.729 (03/1996), Coding of speech at 8 kbit/s using conjugate-structure
algebraic-code-excited linear-prediction (CS-ACELP).
ITU-T Recommendation P.48 (11/1988), Specification for and Intermediate Reference System.
ITU-T Recommendation P.51 (08/1996), Artificial mouth.
ITU-T Recommendation P.58 (08/1996), Head and torso simulator for telephonometry.
ITU-T Recommendation P.79 (09/1999), Calculation of loudness ratings for telephone sets.
ITU-T Recommendation P.340 (05/2000), Transmission characteristics and speech quality
parameters of hands-free terminals.
ITU-T Recommendation P.501 (05/2000), Test signals for use in telephonometry.
ITU-T Delayed Contribution Com 12 No. D.34, Calculation of WB-Weights for wideband telephony,
Nortel Networks, 2001.
ITU-T Delayed Contribution Com 12 No. D.65, W-Weights for wideband telephony using the one
metre air path to the Eardrum Reference Point as fundamental reference system, Nortel Networks,
2002.
TIA-920-2002, Transmission Requirements for Wideband Digital Wireline Telephones.
TSB-31-C, Part 68 Rationale and Measurement Guidelines for US Network Protection.
UL 60950-1, UL Standard for Safety for Information Technology Equipment – Safety – Part 1:
General Requirements, First Edition, April 2003.
47 CFR Part 68, Connection of Terminal Equipment to the Telephone Network.
Handbook on Telephonometry, CCITT, 1987.
66