Spectral analysis of english fricatives /s/ and /ʃ/ produced by people with profound hearing loss

Abstract

Purpose Hearing loss not only causes restricted speech understanding, but also alters speech production resulting in poor intelligibility. This study investigated whether English fricatives /s/ and /ʃ/ spoken by people with severe-to-profound hearing loss acoustically differ from those spoken by normal hearing (NH) individuals. Methods For hearing impaired (HI) group, we analyzed a part of deaf speech corpus collected at the Speech Perception Assessment Lab (SPAL) at the University of Memphis. From the big dataset, /aSa/ and /aSha/ recordings spoken by eight females were selected. For NH control group, Shannon’s consonant set (1999) spoken by eight females was used. A set of spectral moment analysis (Mean, Variance, Skewness, Kurtosis) along with spectral peak (SP) and wiener entropy (WE) were used as measures of spectral properties of /s/ and /ʃ/. Results Variance and WE for HI were significantly higher than those for NH group (p<0.05). Mean and SP for /s/ were significantly greater in NH group, while Mean and SP for /ʃ/ were significantly greater in HI group (p<0.05). This trends suggest greater Mean and SP differences between /s/ and /ʃ/ for NH group than HI group. Conclusions Based on our finding, Variance and WE are spectral measures that are different between NH and HI individuals’ spoken /s/ and /ʃ/. We assume that HI individuals likely pronounce /s/ and /ʃ/ without making clear distinction substituting by each other due probably to lack of auditory feedback or failure of motor control. Keywords: Fricatives; Spectral moment analysis; Hearing loss; Deaf speech