Phonetic prototypes: Influence of place of articulation and speaking rate on the internal structure of voicing categories

Abstract

In this investigation, the effects of context on the perception of voicing contrasts specified by voice-onset-time (VOT) in syllable-initial stop consonants were examined. In an earlier paper [J.L. Miller and L.E. Volaitis, Percept. Psychophys. 46, 505-512 (1989)], it was reported that the listener's adjustment for one contextual variable, speaking rate, was not confined to the region of the phonetic category boundary, but extended throughout the phonetic category. The current investigation examines whether this type of perceptual remapping also occurs for another contextual variable, the place of articulation of the syllable-initial consonant. In a preliminary experiment that involved acoustic measurement of natural speech, it was confirmed that as place of articulation moves from labial to velar, VOT increases, and it was established that this occurs across a range of speaking rates (syllable durations). In the main experiments, which focused on the voiceless category, it was found that this acoustic change was reflected in perception not only as a shift in the location of the voiced-voiceless category boundary, but also a change in both the specific range of stimuli identified as members of the voiceless category and the set of stimuli judged to be the best exemplars, or prototypes, of the category. These findings extend earlier research by showing that a change in place of articulation, like a change in speaking rate, systematically alters the internal perceptual structure of voicing categories.

The Effect of Speaking Rate on the Role of the Uniqueness Point in Spoken Word Recognition

“…There is evidence that the identity of a vowel is influenced by its duration and that the perceived duration of a vowel is affected by the rhythm of the preceding sound sequence (Ainsworth, 1974). For conso- nants, as speech is slowed, the phonetic category boundary for the contrast between initial voiced and voiceless stops moves toward longer VOT values (Summerfield, 1981), and the range of stimuli perceived as good exemplars of the category becomes wider (Miller & Volaitis, 1989;Volaitis & Miller, 1992). In our study, variations in the length of consonants and vowels that are due to natural rate modifications could affect processing of these segments and, consequently, syllable identification.…”

Typical versions of learned swamp sparrow song types are more effective signals than are less typical versions

“…For song learning accuracy, there may be selection not only for the high level of learning precision observed in swamp sparrows [18] and other species, but also for the categorization and categorical perception of syllables and notes [43]. Research into categorization in speech has clearly shown that humans distinguish between more or less typical phonemes [4][5][6][7][8]. If similar psychological processes underlie preferences in swamp sparrows, this species might provide a model for understanding categorization in learned communication systems.…”

“…It is well established that humans can perceive the degree to which utterances are typical or 'good' exemplars of speech categories [4][5][6][7]. It is still debated exactly how this feat is accomplished: one possible mechanism is by learning 'prototypes', single summary representations of categories stored in long-term memory, while an alternative is by memorization of a large number of individual exemplars [8,9].…”

Dissociable effects of phonetic competition and category typicality in a phonetic categorization task: An fMRI investigation

“…It is also the case that stimuli which are unequivocal in their phonetic category membership may also be poorer members of a phonetic category. Volaitis and Miller showed that voiceless tokens with very long VOTs of 165 msec and greater were judged as poorer phonetic category members than those with shorter VOTs (Miller & Volaitis, 1989;Volaitis & Miller, 1992). Kessinger and Blumstein (manuscript) also showed that stimuli beginning with voiceless stops whose VOT was increased by 4/3 (mean VOT=180 msec, range: 136-225 msec) were rated as poorer exemplars than either unaltered stimuli or those that were increased by 2/3 (mean VOT=129 msec, range: 103-154 msec).…”