Perception of temporal order of vowels and consonant-vowel syllables.

Recent findings indicate that the presence of formant transitions aids the perception of the order of stimuli in repeating sequences of vowels or consonant-vowel (CV) syllables. In this study, 12 listeners reported the perceived order of four vowels or CVs in repeating sequences. Stimuli ranged in duration from 75 to 300 msec in 25-msec steps. Four stimulus sequences were used (1) varying vowels (Vv), (2) CVs with varying consonants but a constant vowel (CvVc), (3) CVs with a constant consonant but varying vowels (CcVv), (4) CVs with consonants and vowels varying (CvVv). Percentage of correct identification of order was significantly higher and mean threshold duration significantly lower for the CvVv and CvVc conditions than for the Vv condition. Mean number of sequences per response was significantly smaller for the CvVv condition than for the other conditions. Threshold durations ranged from 100 msec for the CvVv sequences to 135 msec for the Vv sequences. Ordering performance was nearly perfect for stimulus durations of about 225 to 250 msec. The results support the hypothesis that as stimuli in repeating sequences more closely resemble connected speech, listeners can more easily correctly identify the order of the stimuli.