BINAURAL NOISE-REDUCTION HEARING-AID SCHEME WITH REAL-TIME PROCESSINGIN THE FREQUENCY-DOMAIN

A binaural noise-reduction algorithm for suppressing lateral noise sou rces was implemented in real-time and tested with normal and hearing-i mpaired subjects. With this algorithm, frequency bands with interaural time and amplitude differences characteristic for the ''target'' dire ction of the desired speech sound reach both ears without any attenuat ion. However, frequency bands with an interaural time and amplitude di fference deviating from these desired values are attenuated. Speech qu ality assessments as well as speech intelligibility tests demonstrate a significant noise reduction of up to about 5 dB in signal-to-noise r atio for a dummy-head recorded ''cocktail-party situation'' in an anec hoic chamber. For two additional acoustical situations, however, the s ubjective speech quality from the algorithm degrades with increasing r everberation, while the output from a real-time ''dereverberation'' al gorithm was ranked higher with increasing reverberation. The results w ith hearing-impaired listeners suggest a combination of both algorithm s, while stressing the importance of binaural listening and binaural h earing aids for the rehabilitation of impaired listeners in noisy envi ronments.