Identification of vowels in speech and nonspeech contexts

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Strange, Verbrugge, Schankweiler, and Edman [J. Acoust. Soc. Am. 60, 213–224 (1976)] report that vowels are better identified in the context of a CVC than in isolation. The present study investigates the basis for this difference in performance. One basis might be auditory. In contrast to isolated vowels, CVCs are dynamic acoustic events. If the auditory system is more sensitive to dynamic patterns of stimulation than to unchanging signals, the CVC advantage may follow from that. A different account derives from the various proposals that perceivers of speech are sensitive to the acoustic patterning in a speech signal that specifies the vocal tract gestures of the talker. CVCs may better specify their articulatory source than isolated vowels. These alternative classes of explanation are distinguished here by separating the properties of acoustic change and articulatory specification. Three sets of listening tests were devised. The first consisted of nine different isolated vowels presented six times each in random order. The second presented the same nine vowels in a /b‐b/ context. The third test consisted of the same nine vowels in the context of formant transitions constructed by mirror imaging the /b/ transitions with respect to the steady‐state formants for the vowel. The resulting acoustic patterns include as much acoustic change as the bVb syllables but are not patterns that a vocal tract could produce. Identification of vowels embedded in the mirror‐imaged transitions was substantially worse than that of vowels in isolation or in the context of a CVC. We interpret these findings as supportive of an “articulatory” as opposed to an “auditory” account of the CVC advantage. [This work was supported by NIH Grant HD0‐1994 Haskins Laboratories.]