Perceptual categorization of a compressed vowel space

Acoustic properties of vowel tokens produced by a speaker with radical malformation of the vocal tract have been investigated. A study of vowel formant structures demonstrated that the speaker does not maintain expected intravowel formant relationships which results in a diminished vowel space. However, the speakerapos;s vowel categories do display formant structures which are patterned after the norm [Peterson-Falzone and Landahl, Speech and Language (Academic, New York, 1981), Vol. 6]. The question remains in what way the anomalous formant structures will affect vowel categorization by listeners. A previous report of modeled speech [Landahl and Gould, J. Acoust. Soc. Am. Suppl. 1 77, S100 (1985)] suggests that this speaker's perceived vowel space will not include vowel categories at the periphery. The current study reports perceptual testing of vowel tokens produced by this speaker. The results of these tests concerning the existence of peripheral vowels are in accord with earlier predictions that the speaker would be unable to maintain category distinctions among more central vowels, all vowel categories being compressed in the diminished vowel space. We predicted [I]→[ɛ], [æ]→[ɛ], and [ᴜ]→[ɔ] mismatches. The results are essentially in line with these predictions. [Work supported by NINCDS.]