| Understanding speech in noise is difficult task for both normal hearing and hearing impaired listeners. In hearing impaired listeners, some important speech cues are not audible and hearing aids typically amplify the speech to make it audible, but in presence of noise this benefit is limited. So the amplification of perceptually important cues than amplifying the entire signal is beneficial to improve speech intelligibility in hearing impaired subjects. In this work, several studies are conducted to understand the role of consonant's spectral and amplitude cues for speech intelligibility by hearing impaired and normal hearing listeners. The studies indicated that amplifying consonants is useful and higher frequencies present important information. From the implications of the studies a new method to amplify the higher frequencies and attenuate lower frequencies is developed and formally experimented with normal and hearing impaired listeners. Also experiments are conducted with clean consonants and noisy vowels. The experimental results are obtained to measure the benefits and compare analytically. The results confirmed that clean consonant improved speech intelligibility regardless of SNR level, and new method improved the performance significantly at lower SNRs. |
