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