2022 California Standards for Accessible Design Guide (effective January 1, 2023)
11B-706 Assistive listening systems
11B-706.1 General.
Assistive listening systems required in assembly areas, conference and meeting rooms shall comply with Section 11B-706.
[2010 ADA Standards] 706.1 General. Assistive listening systems required in assembly areas shall comply with 706.
The technical standards for assistive listening systems describe minimum performance levels for volume, interference, and distortion. Sound pressure levels (SPL), expressed in decibels, measure output sound volume. Signal-to-noise ratio (SNR or S/N), also expressed in decibels, represents the relationship between the loudness of a desired sound (the signal) and the background noise in a space or piece of equipment. The higher the SNR, the more intelligible the signal. The peak clipping level limits the distortion in signal output produced when high-volume sound waves are manipulated to serve assistive listening devices.
Selecting or specifying an effective assistive listening system for a large or complex venue requires assistance from a professional sound engineer. The federal Access Board has published technical assistance on assistive listening devices and systems. ◼
11B-706.2 Receiver jacks.
Receivers required for use with an assistive listening system shall include a 1/8 inch (3.2 mm) standard mono jack.
11B-706.3 Receiver hearing-aid compatibility.
Receivers required to be hearing-aid compatible shall interface with telecoils in hearing aids through the provision of neckloops.
11B-706.4 Sound pressure level.
Assistive listening systems shall be capable of providing a sound pressure level of 110 dB minimum and 118 dB maximum with a dynamic range on the volume control of 50 dB.
11B-706.5 Signal-to-noise ratio.
The signal-to-noise ratio for internally generated noise in assistive listening systems shall be 18 dB minimum.
11B-706.6 Peak clipping level.
Peak clipping shall not exceed 18 dB of clipping relative to the peaks of speech.
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