§ 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/ibr_loc
   ations.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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