§ 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 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: Consumer and Governmental Affairs Bureau,
   Reference Information Center, Federal Communications Commission, 445
   12th Street, SW, Washington, DC 20554; and the National Archives and
   Records Administration (NARA). For information on the availability of
   this material at NARA, call 202-741-6030, or go to:
   http://www.archives.gov/federal_register/code_of_federal_regulations/ib
   r_locations.html.

   [ 61 FR 42187 , Aug. 14, 1996, as amended at  64 FR 60726 , Nov. 8, 1999;
    67 FR 13229 , Mar. 21, 2002;  69 FR 18803 , Apr. 9, 2004]

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