Study of Perceptual Balance in Comb Filter Based Spectral Splitting of Speech Signal to Reduce the Effect of Frequency Masking

Earlier investigations have shown that spectral splitting of speech signal helps in reducing the effect of spectral masking for persons with moderate bilateral sensorineural hearing loss. In spectral splitting, the speech signal is filtered using a pair of linear phase FIR comb filters with complementary magnitude responses for binaural dichotic presentation. The filter responses should be such that perceived loudness remains balanced, especially for spectral components in transition bands which get presented to both the ears. Relationship between scaling factors for a tone presented to the two ears, so that perceived loudness is that of a monaural presentation, is investigated for design of comb filters with improved perceptually balanced response. Results from the listening tests show that sum of the two scaling factors should be constant, indicating that the magnitude response of the comb filters should be complementary on a linear scale. KeywordsSensorineural hearing loss, frequency masking, spectral splitting, comb filter, binaural perceptual balance.