Binaural noise reduction for hearing AIDS

Noise reduction algorithms have been proposed that try to imitate some aspects of the binaural information processing in the human hearing system by using two microphones at both ears and a central processor. Based on a two channel input, it is theoretically possible to cancel one interfering directional noise source at a time. Due to the relatively large distance between microphones, it should additionally be possible to detect and cancel reverberation based on coherence measures. In practice however, no significant increase in speech intelligibility has been shown so far with these schemes in acoustically complex environments characterized by diffuse noise and reverberation. This paper summarizes these results for a review. Furthermore, a localization algorithm is introduced, which uses a statistical description of the binaural signal differences in order to increase the robustness in estimating sound source incident directions in noisy environments. Possible noise reduction schemes based on this localization algorithm are discussed.