ASA S3.35-2021 PDF

This standard describes techniques used to measure hearing aids under simulated conditions of real ear use. For the purpose of these measurements, a standard manikin and ear simulator are used to represent a typical hearing aid wearer. Acoustical requirements of the test space as well as how the manikin is positioned with respect to the sound source are given. Two methods are presented to control the level of the incident sound field during the testing. Procedures are provided to obtain both the aided gain and the insertion gain, in order to determine the increase in sound pressure relative to the unaided condition, with and without the acoustical effect of the manikin. Procedures are also provided to obtain the directional response of the hearing aid on the manikin as a function of azimuth and elevation of the sound source, and to calculate the directivity index from the directional response.