Identification of stops and vowels in truncated CV syllables

Abstract

How is the information specifying place of articulation and vowel color encoded in a stop-vowel syllable? Are place cues located in just the burst, or the first 20 ms of a CV waveform as some investigators have suggested? Alternatively, are place cues encoded simultaneously (i.e., in parallel) with vowel information in the formant transitions? To answer these questions, an identification experiment was conducted using the consonants /b, d, g/ paired with the vowels /i, e, a, o, u/ produced by two male talkers. Using computer techniques, five truncated stops were edited from each original syllable. Cuts were made after the release burst, and then the burst plus 1, 3, 5, or 7 pitch pulses. On different days, naive subjects identified either the consonant or the vowel. Identification functions for /b/ and /d/ reached 95% correct within the first 20 ms. Vowels, except for /i/, were identified near chance for the shortest stimuli. The consonant /g/ needed a longer duration, 40 to 50 ms, for correct place identification, although /gi/ was never identified accurately even at the longest durations. We conclude that sufficient acoustic information for identifying the stops /b/ and /d/ can be found within the first 20 ms of a CV syllable, although information for the /g/ extends over somewhat longer durations. Formant transitions appear to carry information about the vowel although somewhat less information about the consonant, except for /g/ before front vowels. [Supported by NINCDS Grant NS-12179.]