The effect of increasing speaking rate on acoustic and perceptual measures of nasality in hearing impaired speakers
Degree GrantorUniversity of Canterbury
Degree NameMaster of Audiology
Nasality is a common resonance disorder present in the speech of severely hearing impaired individuals (Hudgins, 1934). The likely cause has been attributed to structural or functional abnormalities of the velopharyngeal mechanism as well as deviations in pitch and loudness. In addition, hearing impaired individuals speak at a slower rate than normal hearing individuals which has been shown to exacerbate the presence of nasality in their speech (Colton & Cooker, 1968). The purpose of this study was to determine whether deliberate increases in speaking rate would serve to decrease the amount of nasality in the speech of severely hearing impaired individuals. The participants were 11 severe to profoundly hearing impaired students, ranging in age from 12 to 19 years (mean = 16 years). Each participant provided a baseline speech sample (R1) followed by three training sessions during which participants were trained to increase their speaking rate. Following the training sessions, a second speech sample was obtained (R2). Acoustic and perceptual analysis pf the speech samples obtained at R1 and R2 were undertaken. The acoustic analysis focused on changes in first and second formant frequency bandwidth (BW1 & BW2). The perceptual analysis involved 21 naïve listeners rating the speech samples (at R1 & R2) for perceived nasality. Findings indicated a significant increase in speaking rate at R2. In addition, a significantly narrower BW2 frequency and lower perceptual rating score was obtained at R2 across all participants, suggesting a considerable decrease in nasality as speaking rate increases. The influences of speaking rate changes on the functioning of the velopharyngeal mechanism are discussed. In addition, the clinical implications of the findings are explored.