Bilateral digital hearing aids for binaural hearing.

The rehabilitation of binaural hearing performance in hearing impaired listeners has received relatively little attention to date. Both localization ability and speech-understanding-in noise are affected in the impaired listener. When localization performance is tested in impaired ears with conventional hearing aid fittings it is found to be worse than the unaided condition. Advances in electronic design now permit speculation about the implementation of complex digital filters within the confines of an in-the-ear hearing aid. We have begun exploring strategies to enhance the localization performance of impaired listeners with bilateral digital signal processing. We are examining three strategies in bilateral hearing aid design to improve localization performance in hearing impaired listeners, namely 1) more accurate fitting of individual ear losses, 2) equalization of the effect of the hearing aid itself on the acoustics within the ear canal, and 3) binaural fitting strategies which in effect modify individual ear fittings to enhance localization performance. The results of early psychophysical testing suggests that localization performance can be improved with these strategies.