Role of auditory feedback in speech production by cochlear implant users: Acoustic and perceptual analyses

The role of auditory feedback in speech production is one of the classic issues in the field of speech sciences. Auditory feedback is considered important for acquisition of speech. However, once speech acquisition is complete, auditory feedback is used intermittently to fine-tune speech. Recent studies of normal-hearing adults have demonstrated that phonating subjects rapidly compensate for heard shifts in the pitch of vocal feedback within 150-ms, suggesting that suprasegmental features (e.g. fundamental frequency and duration of syllables or phrases) of ongoing speech may be monitored using auditory feedback. However, studies exploring whether segmental features (vowels and consonants) of ongoing speech can be monitored using auditory feedback are limited.;The present study investigates four important questions. First, is speech modified when auditory feedback is unavailable for less than a second? Second, is the extent of modifications in speech features greater for unfamiliar sounds compared to familiar sounds? Third, are these modifications comparatively greater in the speech of congenitally deaf children than in adventitiously deafened adults? Fourth, are modifications in speech following the removal of auditory feedback perceived by normal-hearing listeners?;These questions were addressed by investigating English and French words spoken by deaf children and adults using cochlear implant device in the presence (device on) and absence (device off) of auditory feedback. Subjects' productions were analyzed acoustically and were also presented to normal-hearing listeners' to determine speech quality.;The results indicate that certain segmental and suprasegmental features of speech were modified when auditory feedback was briefly unavailable. The modifications were more pronounced in the speech of deaf children compared to deaf adults, but were not greater in French compared to English words. Finally, speech quality was judged to be better for tokens produced in the presence of auditory feedback than in its absence. The results suggest auditory feedback is used by children and adults in the short-term not to only to maintain speech postures, but also to guide segmental productions to a greater extent than previously thought.