The importance of consonant-vowel intensity ratio in the intelligibility of voiceless consonants.

The purpose of this study was to evaluate the extent to which variations in the consonant-vowel (C-V) intensity ratio could account for variations in speech intelligibility among the productions of 10 talkers. Fifty normal-hearing individuals listened in noise to syllables consisting of voiceless consonants followed by the vowel /a/ under three conditions in which: (a) C-V ratio varied naturally as produced by the talkers, and the stimuli were calibrated according to vowel intensity; (b) C-V ratios were increased and equated via digital signal processing; and (c) C-V ratios were unmodified, but the syllables were calibrated according to consonant level rather than vowel level. Results indicated that variations in C-V ratio explained a great deal of the variation in the intelligibility of some consonants (/s, S, tS/) but not others (the voiceless stops). This difference may well be due to differences in audibility between the two groups of consonants when they are presented at similar consonant-to-noise ratios. The majority of the data suggest that the importance of C-V ratio is related to the intensity of consonants but is independent of the ratio per se between consonant and vowel levels.