Enhancing the perceptual segregation and localization of sound sources with a triple beamformer.

A triple beamformer was developed to exploit the capabilities of the binaural auditory system. The goal was to enhance the perceptual segregation of spatially separated sound sources while preserving source localization. The triple beamformer comprised a variant of a standard single-channel beamformer that routes the primary beam output focused on the target source location to both ears. The triple beam algorithm adds two supplementary beams with the left-focused beam routed only to the left ear and the right-focused beam routed only to the right ear. The rationale for the approach is that the triple beam processing exploits sound source segregation in high informational masking (IM) conditions. Furthermore, the exaggerated interaural level differences produced by the triple beam are well-suited for categories of listeners (e.g., bilateral cochlear implant users) who receive limited benefit from interaural time differences. The performance with the triple beamformer was compared to normal binaural hearing (simulated using a Knowles Electronic Manikin for Auditory Research, G.R.A.S. Sound and Vibration, Holte, DK) and to that obtained from a single-channel beamformer. Source localization in azimuth and masked speech identification for multiple masker locations were measured for all three algorithms. Taking both localization and speech intelligibility into account, the triple beam algorithm was considered to be advantageous under high IM listening conditions.