No abstract

No abstract

Duplex perception-the simultaneous perception of a speech syllable and of a nonspeech "chirp"-occurs when a single formant transition and the remainder (the "base") of a synthetic syllable are presented to different ears. Two experiments were conducted to test whether the speech percept derives from the dichotic fusion of the transition with the base or from phonetic information extracted directly from the isolated transition. Experiment 1 showed that subjects were unable to assign speech labels to isolated transitions in a consistent manner, although the same transitions led to accurate identification when paired with the constant base in the other ear. Experiment 2 used an AXB paradigm to show that selective attention to the ear receiving the base does not prevent the contribution of the contralateral transition to the speech percept. Both experiments support the hypothesis that the speech percept in the duplex situation results from dichotic fusion at a relatively early stage in processing.