Lexical effects on the phonetic categorization of speech: The role of acoustic structure.

Abstract

This study examines the extent to which acoustic parameters contribute to lexical effects on the phonetic categorization of speech. Experiment 1 was designed to replicate previous findings. Two test continua were created varying in voice onset time. Results of both identification and reaction time (RT) range data showed an effect of lexical status at the phonetic boundary, but only in the slowest RT ranges, suggesting that lexical effects on phonetic categorization are postperceptual. Experiment 2 explored whether the lexical effect would emerge when the stimulus continua more nearly approximated the parameter values of natural speech. Both identification and RT range data indicated that the lexical effect disappeared. These results suggest that without attention to the acoustic structure of the stimuli, the role of top-down processing in phonetic categorization may be overemphasized.

The Influence of Neighborhood Density on Phonetic Categorization in Aphasia

“…An alternative view is that highlevellinguistic sources interad directly with phonetic perceptual processes, their relative contribution dependent upon the degree of ambiguity of the acoustic-phonetic signal (Ganong, 1980). This latter view is consistent with research suggesting that lexical effects in phonetic categorization are not matters of course, but emerge when the acoustic signal is unnatural or contains conflicting phonetic eues (Burton, Baum, & Blumstein, 1989). Such theories will be reviewed in the following section.…”

“…This Iimiting of the lexical effect to slow and intermediate ranges has been replicated in studies with similar methodologies that have partitioned responses into such RT ranges (Burton et aL, 1989;Miller & Dexter, 1988;Pitt & Samuel, 1993).…”

“…Il has also been suggested that the unnatural acoustic structure of test stimuli used in previous research may have baen a factor in producing lexical affects (Burton et aL, 1989). Specifically, Burton et al (1989) noted that, in the place-of-artieulatian continua utilized by Fox (1984), the stop consonants were constructed based solely on formant transitions, with no bursts.…”

“…Specifically, Burton et al (1989) noted that, in the place-of-artieulatian continua utilized by Fox (1984), the stop consonants were constructed based solely on formant transitions, with no bursts. This does not reflect the abundance of eues that are available in natural speech.…”

“…HO'Never, it has been noted that ampl itude of both burst and aspiration provide important eues to voicing in stop consonants in natural speech (Repp, 1984) and that other spectral properties of the burst co-vary with VOT (Lisker & Abramson, 1964;Pickett, 1980). To investigate the extent to 'Nhich these acoustic variations may contribute to the lexical effect, Burton et al (1989) …”