Consonants and vowels discriminated differently even when acoustically matched

Abstract

Vowels are reportedly discriminated differently from consonants, but there have typically been large between-class acoustic differences. Discrimination still differed when acoustic differences were reduced by removing the mostly vocalic center portion of CVCs [silent center (SC)] [A. M. Kang and D. H. Whalen, J. Acoust. Soc. Am. 107, 2855–2856 (2000)]. The present study compared consonant and vowel identification and discrimination of synthetic CVCs varying in equal-sized F2 steps along /b-d/ and /ε-ʌ/ continua (full syllables), and in truncated syllables corresponding to the initial 60 ms of the previously examined SC syllables. To lower listener uncertainty, only consonant, or only vowel, information was varied within a test block. Consonant discrimination for full syllables was much higher than in the earlier SC experiment; it was slightly higher for the truncated stimuli than for the full. Vowel discrimination was much higher than consonant, near ceiling for both full and truncated stimuli. Thus, even when acoustic steps are equalized and the speech presented (in the truncated stimuli) is limited to the syllable portion that contains most of the constant information, vowels remain better discriminated than consonants. This indicates a true difference processing of the two phonetic classes, even when the acoustics are well matched. [Work supported by NIH.]