ASA 129th Meeting - Washington, DC - 1995 May 30 .. Jun 06

4aSC11. Effect of relative amplitude, presentation level, and vowel duration on perception of voiceless stop consonants by normal and impaired listeners.

Mark S. Hendrick

Dept. Commun. Disorders, Univ. of Alabama, Tuscaloosa, AL 35487

Walt Jesteadt

Boys Town Natl. Res. Hosp., Omaha, NE 68131

In the present study, previous work on the influence of relative amplitude and presentation level in listeners with normal hearing and those with sensorineural hearing loss is extended to include (1) a comparison of relative amplitude manipulation in the presence of neutral formant transitions versus manipulation of both formant transition and relative amplitude and (2) the additional variable of vowel duration. Synthetic CV stimuli were used, and the amplitude of the burst relative to the vowel in the F4--F5 frequency range was varied across a 20-dB range. In experiment 1, some stimuli had neutral formant transition values and relative amplitude manipulations; other stimuli had both formant transition and relative amplitude manipulations. For stimuli in experiment 2, neutral formant transition values were used, relative amplitude was manipulated, and vowel duration ranged from 14 to 200 ms. Results from experiment showed no significant difference between subject groups when only relative amplitude information was manipulated, but significant differences when both relative amplitude and formant transition information was present. Results from experiment 2 indicated that vowel duration influenced the use of relative amplitude by listeners with normal hearing, but did not have this effect for listeners with sensorineural hearing loss. [Work supported by NIH.]