Telecommunications Industry Association
TR41.9-12-11-007
Document Cover Sheet
Project Number
TIA_PN_31-D-2
Document Title
Receive Volume Control - Conversational Gain
Source
Cisco Systems, Inc.
Contact
Tim Lawler
170 West Tasman Dr.
San Jose, CA 95134
Distribution
TR-41.9
Intended Purpose
of Document
(Select one)
X
Phone: (408) 527-0681
Fax: (408) 853-3288
Email: tlawler@cisco.com
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 October 2009, all
of which provisions are hereby incorporated by reference.
Date submitted: 9/6/2012
Abstract
This contribution provides a new subsection for TSB-31-D on test procedures for doing receive volume
control tests using the conversational gain measurements from TIA-4965.
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TR41.9-12-11-007
REFERENCES
Add the following:
ANSI/TIA-4965-2012, Receive Volume Control Requirements for Digital and Analog Wireline
Terminals
5.5 Suggested Equipment List (SEL)
Change the following:
(28) Frequency selective voltmeter: frequency range from 200 100 Hz to at least 4 8kHz, input
impedance >10 kilohms, balanced input, range 1 microvolt to 1 V, accuracy +3%, bandwidth
10 Hz and 30 Hz.
(53) Microphone amplifier: The frequency response characteristics of this amplifier should be
constant over the frequency range from 100 Hz to 5000 8000 Hz. The input-output
characteristics of this amplifier should be linear for the range of sound pressure levels to be
measured.
Add the following:
(75) Frequency generator with IEEE Std 269 real male speech. The generator level should be
constant over a frequency range of 100 Hz to 8000 Hz.
(76) ITU-T P.58 Head and Torso Simulator (HATS).
(77) L16-256 reference wideband linear, sixteen bit, 256 kbit/s codec.
(78) ITU-T G.722 reference wideband codec (0 dBm0 = 9 dB below full scale).
14.3
Hearing Aid Compatibility - Volume Control (Conversational Gain) 47 C.F.R., 68.317
14.3.1 Background
The HAC Act required the FCC to establish regulations that would ensure reasonable access to
telephone service by persons with hearing disabilities. The FCC requires hearing aid
compatible telephones to provide volume control.
14.3.2 Purpose
To determine that the receive volume control of a telephone with a handset meets specified
requirements in ANSI/TIA-4965 using conversation gain.
14.3.3 Equipment
(1) Frequency generator with IEEE Std 269 real male speech SEL#75.
(2) Frequency selective voltmeter SEL#28.
(3) Level recorder SEL#70.
(4) Head and Torso Simulator (HATS) SEL#76
(5) Type 3.3 Artificial ear SEL#69.
(6) Microphone amplifier SEL#53.
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Telecommunications Industry Association
TR41.9-12-11-007
(7)
Test loop or commercially available artificial loop equivalent to 2.7 km #26 AWG nonloaded cable SEL#50.
(8) G.711 reference codec SEL#74.
(9) L16-256 reference wideband codec SEL#77
(10) G.722 reference wideband codec SEL#78
Note: Refer to subclause 5.5 for equipment details.
14.3.4 Equipment States Subject To Test
Normal off-hook talking condition.
14.3.5 Test procedure
The measurement method for receive volume control for both analog and digital telephones are
in clause 4.4.2 of ANSI/TIA-4965.
14.3.6 Alternative Methods
None
14.3.7 Suggested Test Data
(1) State the type of codec that was used for wideband digital telephones.
(2) State the measured dBSPL.
(3) State the calculated conversational gain.
(4) If the gain at the maximum receive volume control setting exceeds 24 dB, state if the
amplified receive capability automatically resets to a level of 24 dB or less when the
telephone is forced to pass through a proper on-hook transition.
(5) State whether significant clipping was detected at the maximum gain setting. If so, state if
there was a lower volume control setting that provided the minimum required gain without
producing significant clipping.
14.3.8 Comments
(1) This requirement applies to telephones with receive volume control.
(2) The measurement is done with the telephone’s volume control to the maximum.
(3) Test circuits for analog telephones testing is in clause 4.2 of ANSI/TIA-4965.
(4) Test circuits for digital telephones testing is in clause 4.3 of ANSI/TIA-4965.
(5) Conversational gain is calculated by subtracting 70 dB from the measured dBSPL.
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