Telecommunications Industry Association
TR41.3.3-XX-XX-XX
Document Cover Sheet
Project Number
Document Title
TIA 810B and 920A Handset Telephone Loudness Ratings and Overall Levels
Source
MWM Acoustics
Contact
Name:
Complete
Address:
Glenn Hess
Phone:
317-596-1721
Suite 520
Fax:
317-849-8178
Email:
hess@mwmacoustics.com
6602 East 75th Street
Indianapolis, IN 46250
Distribution
Intended Purpose
of Document
(Select one)
TR-41.3.3
X
For Incorporation Into TIA Publication
For Information
Other (describe) -
The document to which this cover statement is attached is submitted to a Formulating Group or
sub-element thereof of the Telecommunications Industry Association (TIA) in accordance with the
provisions of Sections 6.4.1–6.4.6 inclusive of the TIA Engineering Manual dated March 2005, all of
which provisions are hereby incorporated by reference.
Abstract
This document recommends using the ITU-T P.79 narrowband loudness calculations for both narrowband
and wideband IP phones. Furthermore, an SLR target of +8.0 dB and RLR target of +2.0 dB should
continue to be used for both TIA 810B and 920A. These recommendations are based on send, receive,
and sidetone measurements of frequency response, loudness ratings, overall output levels, and RTP audio
packet levels. Also, the 0 dBm0 reference of 3.17 dBFS should continue to be used in 920A for
consistency with 810B. Unfortunately, using this one digital reference does not allow evaluating the IP
phone under optimum conditions for different codec implementations.
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Telecommunications Industry Association
TR41.3.3-XX-XX-XX
(1) Transmission Test Study –
A traditional desktop IP phone with multiple codec implementations was evaluated for loudness ratings
and overall output levels. This study was undertaken to determine the effects of narrowband versus
wideband loudness calculations and the corresponding overall output levels. Furthermore, a comparison
was made when using the 3.17 and 9.00 dBFS digital reference points. Overall, the G.711, L16-256, and
G.722 codecs were included in the test study.
Handset telephone performance was measured on a B&K 4128 Head & Torso Simulator using the Type
3.3 ear simulator with hardness of 35 ±6 degrees Shore-OO. The handset was positioned at the high leak
position using a 10N force. It was not disturbed throughout the testing session. Send, receive, and
sidetone frequency response and loudness rating measurements were made using ITU-T P.50 speech for
each audio codec and digital reference point implemented.
This same P.50 speech signal was also applied to evaluate Real Time Protocol (RTP) audio packets and
measure associated output levels. A network protocol analyzer was used to capture approximately 10
seconds of packet data. These audio packets were analyzed to determine overall signal power relative to
digital full scale (dBFS). Send and receive outputs were measured using a broadband multimeter with 20
second time averaging.
(2) Test Data Collected and Included –
All input/output level data has been tabulated for send, receive, and sidetone. The tables that follow list
the stimulus levels, audio output levels, and RTP network levels. Comparisons are made between four
codec combinations that include the G.711 (3.17), L16-256 (3.17), L16-256 (9.00), and G.722 (9.00). It is
these three tables where the analysis, conclusions, and recommendations are formed.
The frequency response and loudness rating data collected during testing follow the table summaries.
These screen captures were taken during TIA 810B testing for the G.711 codec implementation, and 920
testing for the L16-256 and G.722 codec combinations. In addition, the raw test data was saved in Excel
files for archiving and further analysis.
(3) Summary and Recommendations –
Observations for send, receive, and sidetone are covered in sections 4-6. Two key findings were made in
all the testing conducted. First, narrowband versus wideband loudness ratings due not track overall output
levels measured. Setting identical SLR and RLR targets for 810B and 920 results in a 3.8 dB lower
wideband send output level and 5.6 dB lower wideband receive output level. It also creates interoperability issues between narrowband and wideband telephones, especially in conferencing mode.
Feedback from user trials on this IP phone confirmed our numerical findings. For the product
manufacture, send and receive gain levels were initially set to existing 810B and 920 targets. However,
measurement data and user trials led to design changes based exclusively on SLR and RLR narrowband
calculations. From these results, MWM Acoustics recommends using the ITU-T. P.79 narrowband
calculation for both narrowband and wideband phones while maintaining current SLR and RLR targets.
Second, transmission testing showed that changing the 0 dBm0 reference point directly affects send and
receive. Moving from 3.17 to 9.00 dBFS, as recommended by ITU-T for wideband codecs, increases send
output by 5.83 dB, while reducing receive output this same 5.83 dB factor. MWM Acoustics recommends
using 3.17 dB in TIA 810B and 920A for consistency of results. Unfortunately, this compromises the
design and operation of codecs using a different 0 dBm0 reference.
Page 2 of 11
Telecommunications Industry Association
TR41.3.3-XX-XX-XX
(4) Send P.50 Speech – Brand X #7D Handset IP Phone
Send Overall Stimulus and Measurement Levels
G.711 (3.17)
L16-256 (3.17)
L16-256 (9.00)
G.722 (9.00)
Send Stimulus
Send Stimulus
Send Stimulus
Send Stimulus
Source = -4.7 dBPa
Source = -4.7 dBPa
Source = -4.7 dBPa
Source = -4.7 dBPa
Send Measurement
RTP Pkt = -21.0 dBFS
Send Out = -17.8 dBm0
Send Measurement
RTP Pkt = -20.9 dBFS
Send Out = -17.7 dBm0
Send Measurement
RTP Pkt = -20.8 dBFS
Send Out = -11.8 dBm0
Send Measurement
RTP Pkt = -30.8 dBFS
Send Out = -21.7 dBm0
SLRw = +6.6 dB
SLR = +8.8 dB
SLRw = +4.9 dB
SLR = +8.7 dB
SLRw = -1.0 dB
SLR = +2.8 dB
SLRw = +8.9 dB
SLR = +12.8 dB
Note – Phone’s send
path gain decreased
9.8dB relative to G.711
Testing Notes –
 A P.50 speech signal with an overall -4.7 dBPa input level at MRP was applied for all testing.

The RTP packet data originating from the IP phone was captured using a network protocol
analyzer and evaluated to determine overall signal power.
Observations –
 Wideband send output levels are lower by 3.8 dB compared to narrowband when normalizing the
G.711 (3.17) and L16-256 (3.17) data to their respective SLR and SLRw targets (+8.0) defined in
TIA 810B and 920.

Changing the 3.17 dBFS reference to 9.00 dBFS increases send output by 5.9 dB on the L16-256
codec for the same specified input signal. This is consistent with the 5.83 dB difference in 0
dBm0 reference points.

Implementing the G.722 codec using the 9.00 dBFS reference per ITU-T standards requires 9.6
dB lower send path gain to meet the current 920 SLRw target. This is a combination of the 5.83
dB difference in reference points, and 3.8 dB in SLR versus SLRw output levels.
Recommendations –
 Continue to use TIA 920A send loudness target of +8.0 dB as currently specified, but implement
the narrowband SLR calculation for both narrowband and wideband phones. This will maintain
consistent send output levels and interoperability between products, especially in conferencing.

Continue to use the 3.17 dBFS digital reference for all narrowband and wideband codecs. While
this provides consistency between TIA 810B and 920A, it does not allow testing the IP phone
under optimum conditions for different codecs implemented. This should be the subject of further
discussions given future codec developments may not relate to telecom levels (dBm0).
Page 3 of 11
Telecommunications Industry Association
TR41.3.3-XX-XX-XX
(5) Receive P.50 Speech – Brand X #7D Handset IP Phone
Receive Overall Stimulus and Measurement Levels
G.711 (3.17)
L16-256 (3.17)
L16-256 (9.00)
G.722 (9.00)
Receive Stimulus
Source = -16.0 dBm0
RTP Pkt = -19.3 dBFS
Receive Stimulus
Source = -16.0 dBm0
RTP Pkt = -19.3 dBFS
Receive Stimulus
Source = -16.0 dBm0
RTP Pkt = -25.1 dBFS
Receive Stimulus
Source = -16.0 dBm0
RTP Pkt = -25.0 dBFS
Receive Measurement
Rec Out = -11.4 dBPa
Receive Measurement
Rec Out = -10.4 dBPa
Receive Measurement
Rec Out = -16.0 dBPa
Receive Measurement
Rec Out = -16.3 dBPa
RLRw = +0.2 dB
RLR = +3.4 dB
RLRw = -3.2 dB
RLR = +2.4 dB
RLRw = +2.5 dB
RLR = +8.0 dB
RLRw = +2.9 dB
RLR = +8.2 dB
Note – Phone’s receive
path gain increased 0.8
dB relative to G.711
Note – Phone’s receive
path gain increased 0.8
dB relative to G.711
Note – Phone’s receive
path gain increased 0.8
dB relative to G.711
Testing Notes –
 A P.50 speech signal with an overall –16.0 dBm0 input level was applied for all testing.

The RTP packet data originating from the test PC client was captured using a network protocol
analyzer and evaluated to determine overall signal power.
Observations –
 Wideband receive output levels are lower by 5.6 dB compared to narrowband when normalizing
the G.711 (3.17) and L16-256 (3.17) data to their respective RLR and RLRw targets (+2.0)
defined in TIA 810B and 920.

Changing the 3.17 dBFS reference to 9.00 dBFS decreases receive output by 5.6 dB on the L16256 codec for the same specified input signal. This is consistent with the 5.83 dB difference in 0
dBm0 reference points.

Implementing the G.722 codec using the 9.00 dBFS reference per ITU-T standards requires 0.2
dB higher receive path gain to meet the current 920 RLRw target. This is combination of 5.83 dB
difference in reference points, and 5.6 dB in RLR versus RLRw output levels.
Recommendations –
 Continue to use TIA 920A receive loudness target of +2.0 dB as currently specified, but
implement the narrowband RLR calculation for both narrowband and wideband phones. This will
maintain consistent receive output levels and interoperability between products, especially in
conferencing.

Continue to use the 3.17 dBFS digital reference for all narrowband and wideband codecs. While
this provides consistency between TIA 810B and 920A, it does not allow testing the IP phone
under optimum conditions for different codecs implemented. This should be the subject of further
discussions given future codec developments may not relate to telecom levels (dBm0).
Page 4 of 11
Telecommunications Industry Association
TR41.3.3-XX-XX-XX
(6) Sidetone P.50 Speech – Brand X #7D Handset IP Phone
Sidetone Overall Stimulus and Measurement Levels
G.711 (3.17)
L16-256 (3.17)
L16-256 (9.00)
G.722 (9.00)
Sidetone Stimulus
Sidetone Stimulus
Sidetone Stimulus
Sidetone Stimulus
Source = -4.70 dBPa
Source = -4.70 dBPa
Source = -4.70 dBPa
Source = -4.70 dBPa
Sidetone Measurement
Side Out = -15.7 dBPa
Sidetone Measurement
Side Out = -15.5 dBPa
Sidetone Measurement
Side Out = -15.5 dBPa
Sidetone Measurement
Side Out = -15.5 dBPa
STMR = +15.7 dB
STMR = +15.6 dB
STMR = +15.6 dB
STMR = +15.6 dB
Testing Notes –
 A P.50 speech signal with an overall -4.7 dBPa input level at MRP was applied for all testing.
Observations –
 Sidetone output levels are comparable for the G.711 (3.17) and L16-256 (3.17) data since STMR
calculations are the same as defined in TIA 810B and 920.

Changing the 3.17 dBFS reference to 9.00 dBFS does not impact this acoustic input to acoustic
output measurement. The 5.83 dB difference in 0 dBm0 reference points applies to the network
interface only.

Implementing the G.722 codec using the 9.00 dBFS reference per ITU-T standards requires no
change in sidetone path gain to meet the current 920 STMR target.
Recommendations –
 Continue to use TIA 920A sidetone loudness target of +18.0 dB as currently specified, and
implement the same STMR calculation for both narrowband and wideband phones to maintain
consistent sidetone output levels.
Page 5 of 11
Telecommunications Industry Association
TR41.3.3-XX-XX-XX
(7) TIA 920 Send P.50 Speech – Brand X #7D Handset IP Phone (G.722 Codec 9.00)
(8) TIA 920 Send P.50 Speech – Brand X #7D Handset IP Phone (L16-256 Codec 9.00)
Page 6 of 11
Telecommunications Industry Association
TR41.3.3-XX-XX-XX
(9) TIA 920 Send P.50 Speech – Brand X #7D Handset IP Phone (L16-256 Codec 3.17)
(10)
TIA 810B Send P.50 Speech – Brand X #7D Handset IP Phone (G.711 uLaw Codec 3.17)
Page 7 of 11
Telecommunications Industry Association
TR41.3.3-XX-XX-XX
(11)
TIA 920 Receive P.50 Speech – Brand X #7D Handset IP Phone (G.722 Codec 9.00)
(12)
TIA 920 Receive P.50 Speech – Brand X #7D Handset IP Phone (L16-256 Codec 9.00)
Page 8 of 11
Telecommunications Industry Association
TR41.3.3-XX-XX-XX
(13)
TIA 920 Receive P.50 Speech – Brand X #7D Handset IP Phone (L16-256 Codec 3.17)
(14)
TIA 810B Receive P.50 Speech – Brand X #7D Handset IP Phone (G.711 uLaw Codec 3.17)
Page 9 of 11
Telecommunications Industry Association
TR41.3.3-XX-XX-XX
(15)
TIA 920 Sidetone P.50 Speech – Brand X #7D Handset IP Phone (G.722 Codec 9.00)
(16)
TIA 920 Sidetone P.50 Speech – Brand X #7D Handset IP Phone (L16-256 Codec 9.00)
Page 10 of 11
Telecommunications Industry Association
TR41.3.3-XX-XX-XX
(17)
TIA 920 Sidetone P.50 Speech – Brand X #7D Handset IP Phone (L16-256 Codec 3.17)
(18)
TIA 810B Sidetone P.50 Speech – Brand X #7D IP Phone (G.711 uLaw Codec 3.17)
Page 11 of 11