The place of articulation of intervocalic stop consonants is conveyed by temporally distributed spectral information, viz, the formant transitions preceding and following the silent closure interval (Ve and ev transitions). Experiment 1 shows that more than 200 msec of silent closure is needed to hear ve and ev formant transitions as separate phonemic events (geminate stops). As closure duration is reduced, these cues are integrated into a single phonemic percept, and the ve transitions become increasingly redundant (Experiments 2 and 3). ve and CV transitions conveying different places of articulation, on the other hand, are heard as separate phonemes at closure durations as short as 100 msec. If closure duration is further reduced, a single stop is heard whose place of articulation corresponds to the CV transitions (Experiment 3). Even in the absence of ev transitions, VC transitions carry little perceptual weight at very short closure durations (Experiment 4). Despite their apparent redundancy, however, the VC transitions exert a positive bias on the perception of CV transitions at very short closure durations. At closure durations beyond 100 msec, on the other hand, ve and CV transitions interact contrastively in perception and tend to be heard as different phonemes (Experiments 5 and 6). The results of these experiments suggest two different processes of temporal integration in phonetic perception, one taking place at a precategoricallevel, the other combining identical phoneme categories within a certain time span.An intervocalic stop consonant-for example, the Idl in /adez---is produced by rapidly constricting the vocal tract at a point appropriate for the place of articulation of the consonant (e.g., by bringing the tip of the tongue against the alveolar ridge), thereby interrupting the airflow from the lungs for a very brief period, and then releasing the constriction and rapidly returning the vocal tract to a more open configuration. The acoustic consequences of such an articulatory act are schematically illustrated in Figure 1. This stylized spectrogram of /ads/ begins with a steady-state formant pattern specifying the vowel lal and ends with a different steady state specifying the vowel I£!. The silent interval in the center represents the closure of the vocal tract. (In real utterances, the closure interval may be filled with low-amplitude periodicity when the stop consonant is voiced, but silence may be substituted in synthetic utterances without any significant perceptual consequences.) On each side of the closure period, the This research was supported by NICHD Grant HDOI994 to the Haskins Laboratories. Preliminary reports of these data appeared in Repp (Notes 5-7), where also more detailed discussions of some side issues may be found. I thank Alvin Liberman, Quentin Summerfield, and David Isenberg for helpful comments on an earlier draft.formants change rapidly towards the pattern characteristic of the point of occlusion. The transitions from the initial vocalic portion into the closure will be ...