Third International Conference on Spoken Language Processing (ICSLP 94)
Hearing aids that are currently in use can be subdivided into three basic types. In a traditional linear hearing aid, the gain of the instrument is adjusted manually and remains fixed regardless of signal level. In a compression hearing aid, gain is dependent on signal levels. In an automatic frequency response (AFR) hearing aid the frequency-gain characteristic (i.e., both gain and frequency response) are dependent on signal level. Hybrid circuitry in which a digital unit controls analog audio components is being used increasingly in modern hearing aids. This technology allows for the hearing aid to be programmed by an external computer. There are many different kinds of experimental hearing aids. These include complex multi-channel compression amplifiers as well as systems with advanced signal-processing capabilities for noise/reverberation reduction, feedback control and novel techniques for enhancing those features of the speech signal that are either inaudible or misheard as a result of the hearing impairment.
Bibliographic reference. Levitt, Harry (1994): "on communication disabilities ********* technologies for signal processing hearing AIDS", In ICSLP-1994, 2095-2098.