When speakers have difficulty hearing their own voice, they tend to speak more clearly. This study investigated whether consonant-suppressed auditory feedback (CAF) alters speech production. Based on previous findings that increasing consonant amplitudes improves speech intelligibility (Gordon-Salant, 1986), we hypothesized that CAF, which suppresses only the consonant segments, would result in speech with enhanced consonants. The CAF system was implemented using Audapter (Cai et al., 2008), and consonants were detected by identifying segments with high-frequency energy components. The two conditions, normal auditory feedback and CAF, were presented in a randomized order. Stimuli containing the voiceless sibilant fricatives /asa/ and /aɕa/ were randomly presented to five adult native speakers of Japanese, who were asked to read them aloud. Averaged power was calculated for the amplitude of the consonant, the initial vowel, and the following vowel in the recorded speech. The results indicated that the averaged power amplitude of both consonants tended to increase under the CAF condition, whereas that of the following vowel tended to decrease. These findings suggest that CAF induces changes in speech production, selectively enhancing the voiceless sibilant fricative consonant segments.
Shimizu et al. (Wed,) studied this question.