ANSI/ASA S3.6:2018

Audiometers are electronic instruments intended for the testing of human hearing. This standard includes specifications and tolerances for audiometers and standard reference threshold levels for audiometric transducers such as supra-aural, circumaural, and insert earphones; bone vibrators; and loudspeakers.
This standard classifies audiometers according to the type of signal generated (pure tones, speech, or both), mode of operation, and complexity or range of auditory functions tested. Audiometers are also classified by type and class. Audiometers used for pure-tone diagnostic assessment are classified as Type 1, 2, or 3, while audiometers having only air-conduction capability are classified as Type 4. Audiometers used for speech assessment are classified as class A or B according to the complexity of the instrument’s capability.
Purpose
The purpose of this standard is to ensure that tests of hearing, and particularly tests of hearing threshold, performed on the same individual with different audiometers complying with this standard shall give equivalent results when used under comparable test conditions. Further, the test results shall accurately and validly represent the level difference, if any, that may exist between the threshold of the individual tested and the reference threshold of hearing. This standard covers the general specifications for audiometers that require behavioral responses from a listener, as well as specific requirements governing the functional units of audiometric equipment such as type or types of signal, signal level control mechanisms, and types of transducers. In addition, instruments which are not audiometers but are used primarily for audiometric testing purposes which incorporate calibrated sound sources (e.g., acoustic immittance systems, otoacoustic emission systems, or narrowband noise generators), shall, whenever possible, conform to clauses 4 through 10 of this standard.