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

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.