Sec. 68.317  Hearing aid compatibility volume control: Technical 
          standards.

    (a) An analog telephone complies with the Commission's volume 
control requirements if the telephone is equipped with a receive volume 
control that provides, through the receiver in the handset or headset of 
the telephone, 12 dB of gain minimum and up to 18 dB of gain maximum, 
when measured in terms of Receive Objective Loudness Rating (ROLR), as 
defined in paragraph 4.1.2 of ANSI/EIA-470-A-1987 (Telephone Instruments 
With Loop Signaling) . The 12 dB of gain minimum must be achieved 
without significant clipping of the test signal. The telephone also 
shall comply with the upper and lower limits for ROLR given in table 4.4 
of ANSI/EIA-470-A-1987 when the receive volume control is set to its 
normal unamplified level.

    Note to paragraph (a): Paragraph 4.1.2 of ANSI/EIA-470-A-1987 
identifies several characteristics related to the receive response of a 
telephone. It is only the normal unamplified ROLR level and the change 
in ROLR as a function of the volume control setting that are relevant to 
the specification of volume control as required by this section.

    (b) The ROLR of an analog telephone shall be determined over the 
frequency range from 300 to 3300 HZ for short, average, and long loop 
conditions represented by 0, 2.7, and 4.6 km of 26 AWG nonloaded cable, 
respectively. The specified length of cable will be simulated by a 
complex impedance. (See Figure A.) The input level to the cable 
simulator shall be -10 dB with respect to 1 V open circuit from a 900 
ohm source.
    (c) A digital telephone complies with the Commission's volume 
control requirements if the telephone is equipped with a receive volume 
control that provides, through the receiver of the handset or headset of 
the telephone, 12 dB of gain minimum and up to 18 dB of gain maximum, 
when measured in terms of Receive Objective Loudness Rating (ROLR), as 
defined in paragraph 4.3.2 of ANSI/EIA/TIA-579-1991 (Acoustic-To-Digital 
and Digital-To-Acoustic Transmission Requirements for ISDN Terminals). 
The 12 dB of gain minimum must be achieved without significant clipping 
of the test signal. The telephone also shall comply with the limits on 
the range for ROLR given in paragraph 4.3.2.2 of ANSI/EIA/TIA-579-1991 
when the receive volume control is set to its normal unamplified level.
    (d) The ROLR of a digital telephone shall be determined over the 
frequency range from 300 to 3300 Hz using the method described in 
paragraph 4.3.2.1 of ANSI/EIA/TIA-579-1991. No variation in loop 
conditions is required for this measurement since the receive level of a 
digital telephone is independent of loop length.
    (e) The ROLR for either an analog or digital telephone shall first 
be determined with the receive volume control at its normal unamplified 
level. The minimum volume control setting shall be used for this 
measurement unless the manufacturer identifies a different setting for 
the nominal volume level. The ROLR shall then be determined with the 
receive volume control at its maximum volume setting. Since ROLR is a 
loudness rating value expressed in dB of loss, more positive values of 
ROLR represent lower receive levels. Therefore, the ROLR value 
determined for the maximum volume control setting should be subtracted 
from that determined for the nominal volume control setting to determine 
compliance with the gain requirement.
    (f) The 18 dB of receive gain may be exceeded provided that the 
amplified receive capability automatically resets to nominal gain when 
the telephone is

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caused to pass through a proper on-hook transition in order to minimize 
the likelihood of damage to individuals with normal hearing.
    (g) These incorporations by reference of paragraph 4.1.2 (including 
table 4.4) of American National Standards Institute (ANSI) Standard 
ANSI/EIA-470-A-1987 and paragraph 4.3.2 of ANSI/EIA/TIA-579-1991 were 
approved by the Director of the Federal Register in accordance with 5 
U.S.C. 552(a) and 1 CFR part 51. Copies of these publications may be 
purchased from the American National Standards Institute (ANSI), Sales 
Department, 11 West 42nd Street, 13th Floor, New York, NY 10036, (212) 
642-4900. Copies also may be inspected during normal business hours at 
the following locations: Federal Communications Commission, 2000 M 
Street, NW., Public Reference Room, Room 220, Washington, DC 20554; and 
Office of the Federal Register, 800 N. Capitol Street, NW., suite 700, 
Washington, DC.

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[GRAPHIC] [TIFF OMITTED] TCJN91.032


[61 02 FR 42187 , Aug. 14, 1996]