An Investigation of Vowel Organization in Speakers With Severe and Profound Hearing Loss Vowel auditory formant distances were obtained from speakers with hearing loss to investigate how perceptual constraints affect the contrastiveness and intelligibility of their spoken vowels. These distances were evaluated in relation to the 3-Bark critical distance principle for vowel height and place as described by Syrdal (1985)  and Syrdal and ... Research Article
Research Article  |   August 01, 1994
An Investigation of Vowel Organization in Speakers With Severe and Profound Hearing Loss
 
Author Affiliations & Notes
  • Helen A. McCaffrey
    The University of Texas at Dallas
  • Harvey M. Sussman
    The University of Texas at Austin
  • Contact author: Helen A. McCaffrey, Callier Center for Communication Disorders, 1966 Inwood Road, Dallas, TX 75235.
Article Information
Hearing Disorders / Speech, Voice & Prosody / Hearing / Research Articles
Research Article   |   August 01, 1994
An Investigation of Vowel Organization in Speakers With Severe and Profound Hearing Loss
Journal of Speech, Language, and Hearing Research, August 1994, Vol. 37, 938-951. doi:10.1044/jshr.3704.938
History: Received December 8, 1992 , Accepted February 18, 1994
 
Journal of Speech, Language, and Hearing Research, August 1994, Vol. 37, 938-951. doi:10.1044/jshr.3704.938
History: Received December 8, 1992; Accepted February 18, 1994

Vowel auditory formant distances were obtained from speakers with hearing loss to investigate how perceptual constraints affect the contrastiveness and intelligibility of their spoken vowels. These distances were evaluated in relation to the 3-Bark critical distance principle for vowel height and place as described by Syrdal (1985)  and Syrdal and Gopal (1986) . Seven speakers with profound hearing loss, 10 with severe hearing loss, and seven with normal hearing produced the vowels /u/, /i/, /r/, /æ/, /a/, and /v/ in an /hVt/ context. Vowel formants and fundamental frequencies were obtained with acoustic spectrographic and LPC analysis and converted to Bark values to establish auditory formant distances. Confusion matrices were constructed from normal listeners’ identifications of recorded vowel productions. When frequency data were transformed to a Bark auditory scale, increasing convergence of vowel targets was obtained with increase in hearing loss. Percent correct identifications of the vowels produced by the three groups reflected speaker group differences seen in vowel contrastiveness/ overlap in auditory phonetic space. Four levels of performance based on error incidence and type were determined. F1-F0 by F3-F2 Bark distance coordinate plots of a given speaker’s vowel space reflected the differential intelligibility scores shown by confusion matrices of individual speakers from the four performance levels. Vowel organization by speakers with hearing loss was influenced by (a) formant critical distance, and (b) formant audibility. The least audible formants, F2 and F3, showed the greatest effects of severe and profound hearing loss. F1 and F0 showed further change with the most profound losses and revealed individual differences as well.

Acknowledgments
The authors wish to acknowledge the following for supplying subjects for this investigation: Listen Acoupedic Center, Houston School for the Deaf, and Sunshine Cottage School for Deaf Children. The manuscript is based on a doctoral dissertation by the first author from the University of Texas at Austin. Randy Diehl, Linda Thibodeau, Fred Martin, and Michael Cannito provided editorial comments and their contributions are greatly appreciated.
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