Effects of short- and long-term changes in auditory feedback on vowel and sibilant contrasts.
OBJECTIVE
To assess the effects of short- and long-term changes in auditory feedback on vowel and sibilant contrasts and to evaluate hypotheses arising from a model of speech motor planning.


METHODS
The perception and production of vowel and sibilant contrasts were measured in 8 postlingually deafened adults prior to activation of their cochlear implant speech processors, 1 month postactivation, and 1 year postactivation. Measures were taken postactivation both with and without auditory feedback. Contrast measures were also made for a group of speakers with reportedly normal hearing speaking with masked and unmasked auditory feedback.


RESULTS
Vowel and sibilant contrasts, measured in the absence of auditory feedback after 1 month of prosthesis use, were diminished compared with their values measured before prosthesis. Contrasts measured in the absence of auditory feedback after 1 year's experience with the prosthesis were increased compared with their values after 1 month's experience. In both time samples, contrasts were enhanced when auditory feedback was restored.


CONCLUSIONS
The provision of prosthetic hearing to postlingually deafened adults impaired their phonemic contrasts at first, as their auditory feedback had novel characteristics. Once auditory feedback became recalibrated with prosthesis use, it could, in turn, revise feedforward commands that control the contrasts in its absence.
Northeastern University, Boston, Massachusetts, USA. lane@neu.edu
Harlan
H
Lane
Melanie L
ML
Matthies
Frank H
FH
Guenther
Margaret
M
Denny
Joseph S
JS
Perkell
Ellen
E
Stockmann
Mark
M
Tiede
Jennell
J
Vick
Majid
M
Zandipour
D000328:Adult; D000367:Age Factors; D000368:Aged; D001184:Articulation Disorders / Q000209:etiology / Q000503:physiopathology*; D003054:Cochlear Implants; D003638:Deafness / Q000150:complications / Q000503:physiopathology* / Q000601:surgery*; D030141:Feedback, Psychological / Q000502:physiology*; D006309:Hearing; D006801:Humans; D008875:Middle Aged; D010700:Phonetics; D013060:Speech