The Effects of Changes in Hearing Status in Cochlear Implant Users on the Acoustic Vowel Space and CV Coarticulation In order to examine the role of hearing status in controlling coarticulation, eight English vowels in /bVt/ and /dVt/ syllables, embedded in a carrier phrase, were elicited from 7 postlingually deafened adults and 2 speakers with normal hearing. The deaf adults served in repeated recording sessions both before and up ... Research Article
Research Article  |   June 01, 2001
The Effects of Changes in Hearing Status in Cochlear Implant Users on the Acoustic Vowel Space and CV Coarticulation
 
Author Affiliations & Notes
  • Harlan Lane, PhD
    Research Laboratory of Electronics Massachusetts Institute of Technology Cambridge and Northeastern University Boston, MA
    Department of Psychology, Northeastern University, 180 NI, Boston, MA 02115
  • Melanie Matthies
    Research Laboratory of Electronics Massachusetts Institute of Technology Cambridge and Boston University Boston, MA
  • Joseph Perkell
    Research Laboratory of Electronics Massachusetts Institute of Technology Cambridge
  • Jennell Vick
    Research Laboratory of Electronics Massachusetts Institute of Technology Cambridge
  • Majid Zandipour
    Research Laboratory of Electronics Massachusetts Institute of Technology Cambridge
  • Corresponding author: e-mail: lane@neu.edu
Article Information
Hearing Aids, Cochlear Implants & Assistive Technology / Speech, Voice & Prosody / Speech / Research Articles
Research Article   |   June 01, 2001
The Effects of Changes in Hearing Status in Cochlear Implant Users on the Acoustic Vowel Space and CV Coarticulation
Journal of Speech, Language, and Hearing Research, June 2001, Vol. 44, 552-563. doi:10.1044/1092-4388(2001/043)
History: Received May 19, 2000 , Accepted January 31, 2001
 
Journal of Speech, Language, and Hearing Research, June 2001, Vol. 44, 552-563. doi:10.1044/1092-4388(2001/043)
History: Received May 19, 2000; Accepted January 31, 2001
Web of Science® Times Cited: 26

In order to examine the role of hearing status in controlling coarticulation, eight English vowels in /bVt/ and /dVt/ syllables, embedded in a carrier phrase, were elicited from 7 postlingually deafened adults and 2 speakers with normal hearing. The deaf adults served in repeated recording sessions both before and up to a year after they received cochlear implants and their speech processors were turned on. Each of the two hearing control speakers served in two recording sessions, separated by about 3 months. Measures were made of second formant frequency at obstruent release and at 25 ms intervals until the final obstruent.

An index of coarticulation, based on the ratio of F2 at vowel onset to F2 at midvowel target, was computed. Changes in the amount of coarticulation after the change in hearing status were small and nonsystematic for the /bVt/ syllables; those for the /dVt/ syllables averaged a 3% increase—within the range of reliability measures for the 2 hearing control speakers. Locus equations (F2 at vowel onset vs. F2 at vowel midpoint) and ratios of F2 onsets in point vowels were also calculated. Like the index of coarticulation, these measures tended to confirm that hearing status had little if any effect on coarticulation in the deaf speakers, consistent with the hypothesis that hearing does not play a direct role in regulating anticipatory coarticulation in adulthood.

With the restoration of some hearing, 2 implant users significantly increased the average spacing between vowels in the formant plane, whereas the remaining 5 decreased that measure. All speakers but one also reduced vowel duration significantly. Four of the speakers reduced dispersion of vowel formant values around vowel midpoint means, but the other 3 did not show this effect.

Acknowledgments
This work was supported by research grant number R01 DC03007 from the National Institute on Deafness and Other Communication Disorders, National Institutes of Health. We are very grateful to Don Eddington and Maggie Whearty of the Massachusetts Eye and Ear Infirmary for subject referrals and to the subjects for their participation.
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