ASA 128th Meeting - Austin, Texas - 1994 Nov 28 .. Dec 02
3aSP18. The effects of duration changes on the perception of vowel
sequences.
Magdalene H. Chalikia
Tammy Dresser
Dept. of Psychol., Moorhead State Univ., Moorhead, MN 56563)
Previous studies have shown that listeners exposed to a repeated sequence
of steady-state vowels of same duration and pitch) experience phonemic
transformations, and report hearing words and phrases absent in the original
stimulus. A previous study [M. H. Chalikia, R. Meyer, and R. Lindemann, 34th
Psychon. Society Meet. 1993)] investigated the possible effects of variations
in vowel duration. Duration variations ranged from 30 to 120 ms per vowel.
Listeners successfully matched these stimuli to the verbal forms heard with
vowels of equal duration and pitch, confirming the robust, stable nature of the
verbal organizations. It was suggested that these organizations are based upon
objective acoustic characteristics, and the stimulus manipulations were
probably perceived as prosodic variations. In this study a broader variation in
duration was employed 10--300 ms), in an attempt to examine listeners'
limitations in performing the matching task. Six base-line sequences of six
80-ms vowels at 100 Hz), followed by a 300-ms silent gap, were used. Four
variations of these were created by randomly changing the duration of
individual vowels within a sequence. Most listeners were not able to perform
the task. Implications concerning the perceptual organization of speech will be
discussed.