Signal Processing for Severe-to-Profound Hearing Loss

Wide dynamic range compression has become the mostly used signal processing strategy for mild to moderate hearing losses although there is still some discussion going on regarding the details of such compression systems. Furthermore, sophisticated signal processing strategies such as automatic program selection, adaptive digital directional microphones and sophisticated noise canceling schemes have been developed and applied in modern digital hearing instruments. Digital technology offers a great deal of flexibility for easily designing and implementing new signal processing algorithms. The most common strategy applied with individuals who have severe-to-profound hearing loss has been to provide them with as much power as possible. However, so far few attempts have been undertaken to apply more sophisticated signal processing strategies with this segment of the hearing-impaired population. In this paper we will review existing knowledge on basic psychoacoustic mechanisms, speech perception as well as different approaches to optimally amplify and process sounds for the group of severely to profoundly hearing impaired subjects.