Phonetic Category Structure of [I] Extent, Best Exemplars, and Organization Research Article
Research Article  |   December 01, 1997
Phonetic Category Structure of [I]
 
Author Affiliations & Notes
  • Joan E. Sussman, PhD
    State University of New York at Buffalo
    122 Park Hall, State University of New York at Buffalo, Buffalo, NY 14260
  • Brian Gekas
    State University of New York at Buffalo
Article Information
Speech, Voice & Prosody / Hearing / Research Articles
Research Article   |   December 01, 1997
Phonetic Category Structure of [I]
Journal of Speech, Language, and Hearing Research, December 1997, Vol. 40, 1406-1424. doi:10.1044/jslhr.4006.1406
History: Received April 29, 1996 , Accepted May 28, 1997
 
Journal of Speech, Language, and Hearing Research, December 1997, Vol. 40, 1406-1424. doi:10.1044/jslhr.4006.1406
History: Received April 29, 1996; Accepted May 28, 1997

The current investigation examined the structure of the phonetic category [I] for 13 listeners. Experiments reported are results from identification, "best exemplar," and discrimination tasks using 105 [I] stimuli. The tokens were synthesized along a mel-spaced vowel continuum that differed in first and second formants. All stimuli ended in a 30 ms [b] sound. Results showed that 10 of 13 listeners demonstrated differing choices of the best exemplars, although most were within 37.5 mels of the central best exemplar chosen in the first experiment. Seven of the participants demonstrated "circular" patterns in identification of the [I] category that appeared to be organized around a central "best exemplar." Six participants showed other identification patterns: "downward, " "upward," and "left-extending," with "best exemplars" on an edge or border of the phonetic categories. Graded category structure from a central "best exemplar" was apparent only in the averaged identification results, and not for individual participants. The size of the [I] category was significantly smaller than that surrounding the [i] best exemplar reported in a prior study by Sussman and Lauckner-Morano (1995). Finally, listeners had equivalent or better discrimination sensitivity with the best exemplar as the fixed standard compared to that for a "poor" exemplar token 45 mels away from the best exemplar. Results showed that phonetic category structure for the lax vowel [I] was different from the similar, but tense vowel [i]. The findings question whether prototype theory is generalizable to vowel categories other than [i].

Acknowledgments
The current research was supported in part by a Working Quality of Life Award to the first author from New York State-United University Professions.
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