2010 ADA Standards for Accessible Design Pocket Guide
407.4.8.2 Audible Indicators.
Audible indicators shall comply with 407.4.8.2.
The signal shall be an automatic verbal annunciator which announces the floor at which the car is about to stop. [S.H. 4.10.13]
EXCEPTION: For elevators other than destination-oriented elevators that have a rated speed of 200 feet per minute (1 m/s) or less, a non-verbal audible signal with a frequency of 1500 Hz maximum which sounds as the car passes or is about to stop at a floor served by the elevator shall be permitted.
The verbal annunciator shall be 10 dB minimum above ambient, but shall not exceed 80 dB, measured at the annunciator.
The verbal annunciator shall have a frequency of 300 Hz minimum to 3000 Hz maximum.