Normal-hearing subjects' recognition of spectrally degraded speech was evaluated under conditions in which the consonant–vowel (C–V) intensity ratio was modified. Subjects identified 22 consonants presented in an a–Consonant–a format at suprathreshold and near threshold conditions. Prior to C–V ratio modification, the stimuli were processed to limit spectral information. In the suprathreshold experiment, stimuli were presented at the natural C–V ratio and at six modified C–V ratios. C–V ratio manipulations had dramatic effects on recognition scores for some groups of consonants. Scores for glides and sibilant fricatives increased with increasing C–V ratio, while scores for nasals and weak fricatives were best at low C–V ratios. Recognition scores for the stops and affricates were generally independent of C–V ratio. For nearly all consonants, changes in recognition scores as a function of C–V ratio were associated with changes in a general response bias toward those sounds. Performance was poor when the spectrally smeared VCVs were presented at low SN ratios in a second experiment. The influence of C–V ratio on percent correct scores was generally similar to the suprathreshold results, but consonant audibility, which was not a factor in the suprathreshold experiment, appeared to alter the effect of C–V ratio modification for some consonants.
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