Time Varying IIR Filters for Binaural Hearing Aids

Due to masking in the places with more noise, people with sensorineural hearing loss (SNHL) have trouble understanding speech. The impact of frequency masking of spectrum components can be reduced by splitting speech signal spectrally into two parts using a set of time varying IIR filters that possess magnitude responses complementary to each other for binaural dichotic presentation. As a result, speech perception is improved. Using a Yule-Walker method, filters having 22 one-third octave bands varying from 0 kHz to 11 kHz, and the continuous change in magnitude responses having time shifts considered below just noticeable difference (JND) are implemented. A set of IIR time-varying (band pass filters’ bank) filters possess complementary magnitude responses with order 25. This improves gap-identifying ability without negating the benefit of the spectral splitting method. The assessment of filter functionality is carried out employing the Modified Rhyme Test (MRT) for speech intelligibility. MRT test is examined on people with normal hearing by adding white noise with various SNRs. Speech signals used for the assessment of filter functionality are 300 monosyllabic CVC (Consonant Vowel Consonant) words. It is found by the results that the understanding and interpretation of processed speech in places with more noise are improved.