Compatibility of a hearing aid and a telephone
J. J. Wojcik, H. Arndt · The Journal of the Acoustical Society of America · 1977
A telephone receiver is designed to generate an acoustic pressure in the ear cavity. This is the output specified by most Telephone Administrations. However, hearing aids don't have the ability to pick up exactly this specified telephone output (with exception of the in-the-ear type). This paper describes the pros and cons of several methods of a hearing aid coupling to a telephone receiver. The most common methods make use of (1) acoustic-leak radiation from the telephone receiver picked up by a hearing-aid microphone; (2) stray magnetic radiation from the telephone receiver picked up by a hearing-aid telecoil; (3) acoustomagnetic or magnetoacoustic active couplers; and (4) acoustic passive adaptors. Criteria for evaluation include acoustic signal quality, users convenience, uniformity, and versatility.