Perception Of Voice Onset Time Research Articles

Voice onset time in aphasia: Thai. I. Perception

This study investigated left brain-damaged aphasic and right brain-damaged non-aphasic patients' ability to label synthetic speech continua differing in voice onset time (VOT) at three places of articulation. The language chosen for investigation was Thai, which exhibits 3 contrasting labial and apical stop categories (voiced, voiceless unaspirated, voiceless aspirated) and 2 contrasting velar stop categories (voiceless unaspirated, voiceless aspirated). Results of the labelling task indicated an impairment in VOT perception at all three places of articulation across clinical types of aphasia. Normal performance by the right brain-damaged patient indicated that deficits in VOT perception can be attributed to pathology specific to the language-dominant hemisphere. No relation was found between the aphasic patient's level of auditory language comprehension and his performance on the VOT perception task. It is suggested that the aphasics' impairment reflects a deficit in phonological processing at the linguistic level.

Hemispheric specialization for temporal information: Implications for the perception of voicing cues during speech perception

Developmental research reporting electrophysiological correlates of voice onset time (VOT) during speech perception is reviewed. By two months of age a right hemisphere mechanism appears which differentiates voiced from voiceless stop consonants. This mechanism was found at 4 years of age and again with adults. A new study is described which represents an attempt to determine a more specific basis for VOT perception. Auditory evoked responses (AER) were recorded over the left and right hemispheres while 16 adults attended to repetitive series of two-tone stimuli. Portions of the AERs were found to vary systematically over the two hemispheres in a manner similar to that previously reported for VOT stimuli. These findings are discussed in terms of a temporal detection mechanism which is involved in speech perception.

Discimination of relative onset time of two-component tones by infants.

A great deal of research has focused on the perception of voice onset time (VOT) differences in stop consonants. Yet, the nature of the mechanisms responsible for the perception of these differences is still the subject of much debate. Recently Pisoni [J. Acoust. Soc. Am. 61, 1352-1361 (1977)] has presented evidence which suggested that the perception of VOT differences by adult listeners may reflect a basic limitation on processing temporal order information by the auditory system. For adults, stimuli with onset differences approximately greater than 20 ms are perceived as successive events (either leading or lagging), while stimuli with onset differences less than about 20 ms are perceived as simultaneous events. Thus, differences in voicing may have an underlying perceptual basis in terms of three well-defined temporal attributes corresponding to leading, lagging, or simultaneous events at onset. The present experiment was carried out to determine whether young infants can discriminate differences in temporal order information in nonspeech signals and whether their discimination performance parallels the earlier data obtained with adults. Discimination was measured with the high-amplitude sucking (HAS) procedure. The results indicated that infants can disciminate differences in the relative onset of two events; the pattern of discrimination also suggested the presence of three perceptual categories along this temporal continuum although the precise alignment of these categories differed somewhat from the values found in the earlier study with adults.

Differences in production and perception of VOT in Polish and English

English and Polish use different Voice Onset Time (VOT) categories to contrast voiced and voicelesstops: short lag and long lag (English) versus prevoiced and short lag (Polish). When VOT is measured for word‐initial stops in minimal pairs, sentences, and conversation, the VOT distributions for voiced and voiceless stops are clearly separated in Polish, but not always in English, especially in casual speech [Lisker and Abramson, Language and Speech 10, 1–28 (1967); Moslin, Brown University dissertation (1978)]. The perception of VOT in synthetic stimuli was compared with production data for Polish and American English listeners. Both groups labeled stimuli in three continua that varied in range of VOT: −20 to + 80, −100 to +50, and −100 to +20 ms VOT. The Polish, but not the American, listeners showed a mean boundary shift (from +20 to +4 ms VOT) as a function of these ranges. Thus the Polish VOT perceptual categories are somewhat unstable and do not always match the VOT production categories, although th...

Speech discrimination in the language-innocent and the language-wise: a study in the perception of voice onset time

ABSTRACTDiscrimination of synthetically produced stimuli differing along the voice onset time continuum was assessed for infants and adults within the context of the Visually Reinforced Infant Speech Discrimination (VRISD) paradigm. English-learning infants' discrimination abilities were compared with two groups of English-speaking adults (a phonetically naive and a phonetically sophisticated group). Contrary to the predictions of the innateness hypothesis, English-learning infants showed evidence of discrimination only across the English phoneme boundary. Adults, on the other hand, were very successful in discriminating both across and within a range of phoneme boundaries. These results are discussed in terms of the presumed relationship between categorical perception and linguistic processing and in terms of synthetic speech continua.

The perception of voice onset time in Polish

Polish is traditionally described as using the prevoiced and short-lag categories to contrast its voiced and voiceless stops. However, Moslin and Keating [J. Acoust. Soc. Am. 62, S27 (A) (1977)] have shown that some speakers of Polish make use of the long-lag, aspirated voicing category. Preliminary results for six speakers of Polish on a/da/-/ta/continuum with VOT from −20 to +80 ms indicate that all speakers, regardless of how they produce their apical stops, show a labeling boundary and discrimination peak at about 35 ms. That is, speakers who rarely if ever produce long-lag stops themselves place their category boundary between the short- and long-lag regions, thus showing a dissociation between production and perception. Further work will vary the test conditions and/or subjects' response categories to determine if a boundary exists between the prevoiced and short-lag regions of the continuum.

Stimulus correlates in the perception of voice onset time (VOT): I. Discrimination of the time interval between tone bursts of different intensities and frequencies

In a four-level 2AFC paradigm, trained subjects had to discriminate time intervals that were marked by tone bursts of unequal duration (10 and 100 msec). Time differences discriminable at the d′ = 1 level, ΔTThresh, were determined in the 10–100-msec range of time intervals (onset to onset). When the frequencies and intensities of all markers were held constant (1 kHz and 86 dB SPL), ΔTThresh was a monotonic function of T. This relation became non-monotonic when the level of the first marker was decreased to 36 dB SPL or as the two marker frequencies were made different from each other by two octaves. Thus, a discrepancy in either the level or the spectrum of two time-marker sounds may constitute an acoustic basis for the nonmonotonic VOT discrimination functions, despite the fact that the depth of the local minimum found in the present data is less than that observed in VOT experiments. [Supported by a grant from NINCDS.]

Stimulus correlates in the perception of voice onset time (VOT): II. Discrimination of speech with high and low stimulus uncertainty

The three Lisker—Abramson CV series (ba-pa, da-ta, ga-ka) were computer synthesized at C.I.D. in 1-msec steps. For each 84-trial block of a high-uncertainty, same-different task (no feedback), one of the three continua was chosen at random. On each trial, the ability of three naive listeners to resolve for differences among VOT pairs ranging from VOT = 10–80 msec, in 10-msec steps was tested. As expected, there was a local maximum performance for each of the three speech continua, thus satisfying one criterion for categorical perception. A minimum-uncertainty AX task (with feedback) was run with three highly trained subjects for the ga-ka continuum. Only one standard VOT was presented in a block of trials. Results were not categorical: the minimum detectable ΔVOT was less than 2 msec at VOT = 10 msec and increased as VOT increased. Our results indicate that trained listeners can utilize subtle stimulus cues in synthetic speech if stimulus uncertainty is minimized. [Supported by a grant from NINCDS.]

The perception of stop consonants by children

Kindergarten and second-grade children's perception of voicing distinctions among the stop consonants was investigated by assessing their ability to identify and discriminate a series of synthetic speech stimuli varying in voice onset time (VOT). Perception of these sounds was found to be nearly categorical. No differences between the two age groups in either identification or discrimination performance were found; furthermore, the children's performance was comparable to adult performance in other studies using these stimuli. When considered in the context of data on the perception of VOT by infants as well as adults, the results suggest that the differential discriminability of stimuli along the VOT continuum has a biological basis.