Vowel Organization in Speakers With Severe and Profound Hearing Loss

This study investigated how perceptual constraints affected the contrastiveness and intelligibility of spoken vowels from speakers with hearing loss. Ten speakers with normal hearing, 10 with severe hearing loss and 10 with profound hearing loss produced the vowels /a/, /i/, hi and IvJ each in a CVC context. Acoustic analyses included measurement of the fundamental frequencies and the first three formant frequencies of each vowel using wide-band FFT spectra were carried out on the speech samples. The frequencies obtained were transformed to Bark auditory scale, which is a scale more closely reflects the processing capacities of the peripheral auditory systems, to establish auditory formant distances. Increasing convergence of vowel targets is obtained with increase in hearing loss. Listener identifications of the vowels produced by the three groups show significant group difference. Factors such as the speakers ' residual hearing, the formant audibility and supplementary visual information of the vowels are likely to be affecting the vowel organization of speakers with hearing loss.