Two acoustic features shown to be sufficient in specifying the distinction between intervocalic /b/ and /p/ are closure duration and the presence or absence of a low‐frequency voicing pulse during the closure interval. These features of the signal can be considered to exhibit a trading relation [B. Repp, Psych. Bull. 92, 81–110 (1982)] to the extent that a longer closure is required to perceive the consonant as voiceless when the pulse is present than when it is not. This study addressed the issue of whether a trading relation of the type found in speech can be demonstrated for nonspeech as well. Two types of square wave analogs, modeled after a speech series ranging from “rabid” to “rapid,” were constructed. One set of nonspeech stimuli contained frequency transitions into and out of the silent interval while frequency for the other nonspeech stimuli remained constant. Preliminary (AXB) identification results indicate that in the speech condition, the presence of the pulse affects a shift in the ID boundary between “rabid” and “rapid” relative to the no‐pulse condition. A comparable shift is observed between the pulse and no‐pulse series in the nonspeech transition condition; no shift is apparent for the nonspeech no‐transition condition. The implications of these results for the notion that speech perception requires a “special” mode of processing will be discussed. [Work supported by NINCDS.]

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