Objective evaluation of the effect of hearing aid use on voice parametres

This study aims to compare the phonetic specifications of individuals with normal hearing and individuals with hearing impairment who either don't use a hearing aid or use unilateral or bilateral hearing aid, by voice analysis. The study is done on four groups, comprising 30 individuals in each group, between 18 and 60 years of age. The first group consisted of 17 female and 13 male who don't use hearing aids in spite of hearing loss; the second group consisted of 13 female, 19 male who use unilateral hearing aid in spite of bilateral hearing loss, the third group consisted of 12 female, 18 malewho use bilateral hearing aid and the fourth group consisted of 15 female, 15 male with normal hearing. The voices of the individuals were recorded via a Trust brand 21964 model microphone and Praat Acoustic Analysis software program version 6.0.31. Vocal shimmer, vocal jitter, main frequency, s/z ratio for /a/ and /i/ phonemes, formants and the harmonic distortion ratios have been inspected. Gender, age, hearing loss and the time of hearing aid usage and hearing loss degree have been taken into account. The acoustic voice analysis results of individuals who use unilateral and bilateral hearing aid and of those who don't use hearing aid in spite of hearing loss have shown quite similar results on fundamental frequencies, intensity level, pulses, vocal shimmer, formants and harmonic noise ratios compared to individuals with normal hearing (p>0.05). But, the vocal jitter parameter of females who use bilateral hearing aid were statistically different than the other groups (p<0.05). The possible reason for differing on jitter parameters of females using bilateral hearing aids is that, the fundamental frequency of female voice is higher than male's. It was thought that high frequency amplification provided by bilateral hearing aids in these individuals had an effect on the voice moniterization of those individuals. To investigate these effects on female, larger-sampled studies including perceptual methods is needed. Keywords: Hearing aid, hearing loss, voice analysis