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Biomedical subjects

D B Pisoni

Publications and source records attributed to D B Pisoni.

88 records · Page 5Linked to original sources
PubMed1981

Variability of vowel formant frequencies and the quantal theory of speech: a first report.

This paper reports the results of a study in which variability of formant frequencies for different vowels was examined with regard to several predictions derived from the quantal theory of speech. Two subjects were required to reproduce eight different steady-state synthetic vowels which were presented repeatedly in a randomized order. Spectral analysis was carried out on the vocal responses in order to obtain means and standard deviations of the vowel formant frequencies. In the spirit of the quantal theory, it was predicted that the point vowel, /i/, /a/ and /u/ would show lower standard deviations than the nonpoint vowels because these vowels are assumed to be produced at places in the vocal tract where small perturbations in articulation produce only minimal changes in the resulting formant frequencies. That is, these vowels are assumed to be quantal vowels. The results of this study provided little support for the hypothesis under consideration. A discussion of the outcome of the results as well as some speculation as to its failure to find support for the quantal theory is provided in the report. Several final comments are also offered about computer simulation studies of speech production and the need for additional empirical studies on vowel production with real talkers.

Computers↗
PubMed1981

Discrimination of voice onset time by human infants: new findings and implications for the effects of early experience.

Discrimination of voice onset time (VOT) by 6--12-month-old infants was examined in 2 experiments. An operant head-turning technique assessed discrimination along a synthetic VOT continuum ranging from -70 msec to +70 msec. Infants from an English-speaking environment provided reliable within-subject evidence for discrimination of VOT contrasts located at both the plus and minus regions of the VOT continuum. These results provide strong evidence that infants from an English-speaking environment are capable of discriminating VOT contrasts that are not phonemic in English. Threshold delta VOT values indicated that the infants were more sensitive to VOT differences in the plus region of the VOT continuum than in the minus region. Threshold delta VOT values from English-speaking adults indicated greater sensitivity at every location along the VOT continuum. In addition, the adults showed heightened sensitivity to VOT differences near the voiced-voiceless boundary in the plus region of the VOT continuum, a finding that was not evident in the infants' data.

Adult↗
PubMed1980

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.

Auditory Perception↗
PubMed1980

Effects of early linguistic experience on speech discrimination by infants: a critique of Eiler, Gavin, and Wilson (1979).

In a recent report in this journal, Eilers, Gavin, and Wilson (1979) presented discrimination data obtained from 2 groups of infants exposed to different language-learning environments. The results showed differences in voice onset time (VOT) discrimination between Spanish and English infants, suggesting an effect of early linguistic experience. A critique of this study indicates that such conclusions about the effects of early experience on speech perception are unwarranted on both methodological and conceptual grounds. Methodological flaws include the absence of reliable statistical analyses and the failure to guard against experimenter bias effects. Conceptual flaws involve the erroneous interpretation of failures to discriminate certain selected speech contrasts. Inferences concerning the developmental course of speech perception in young infants based on the results of the Eilers et al. study need to be interpreted cautiously in light of these serious criticisms.

Discrimination Learning↗
PubMed1979

On the perception of speech sounds as biologically significant signals.

This paper reviews some of the major evidence and arguments currently available to support the view that human speech perception may require the use of specialized neural mechanisms for perceptual analysis. Experiments using synthetically produced speech signals with adults are briefly summarized and extensions of these results to infants and ther organisms are reviewed with an emphasis towards detailing those aspects of speech perception that may require some need for specialized species-specific processors. Finally, some comments on the role of early experience in perceptual development are provided as an attempt to identify promising areas of new research in speech perception.

Adult↗
PubMed1979

Some relationships between speech production and perception.

EMG studies of the American English vowel pairs /i-I/ and /e-epsilon/ reveal two different production strategies: some speakers appear to differentiate the members of each pair primarily on the basis to tongue height; for others the basis of differentiation appears to be tongue tension. There was no obvious reflection of these differences in the speech wave-forms or formant patterns of the two groups. To determine if these differences in production might correspond to differences in perception, two vowel identification tests were given to the EMG subjects. Subjects were asked to label the members of a seven-step vowel continuum, /i/ through /I/. In one condition each item had an equal probability of occurrence. The other condition was an anchoring test; the first stimulus, /i/, was heard four times as often as any other stimulus. Compared with the equal-probability test labelling boundary, the boundary in the anchoring test was displaced toward the more frequently occurring stimulus. The magnitude of the shift of the labelling boundary was greater for subjects using a production strategy based on tongue height than for subjects using tongue tension to differentiate these vowels, suggesting that the stimuli represent adjacent categories in the speakers' phonetic space for the former, but not for the latter, group.

Humans↗
PubMedDate not supplied

Phonotactics, neighborhood activation, and lexical access for spoken words.

Probabilistic phonotactics refers to the relative frequencies of segments and sequences of segments in spoken words. Neighborhood density refers to the number of words that are phonologically similar to a given word. Despite a positive correlation between phonotactic probability and neighborhood density, nonsense words with high probability segments and sequences are responded to more quickly than nonsense words with low probability segments and sequences, whereas real words occurring in dense similarity neighborhoods are responded to more slowly than real words occurring in sparse similarity neighborhoods. This contradiction may be resolved by hypothesizing that effects of probabilistic phonotactics have a sublexical focus and that effects of similarity neighborhood density have a lexical focus. The implications of this hypothesis for models of spoken word recognition are discussed.

Cognition↗
PubMedDate not supplied

Comprehension of synthetic speech produced by rule: a review and theoretical interpretation.

In this paper, we review research on the perception and comprehension of synthetic speech produced by rule. We discuss the difficulties that synthetic speech causes for the listener and the evidence that the immediate result of those difficulties is a delay in the point at which words are recognized. We then argue that this delay in processing affects not only lexical access but also comprehension processes. We consider the mechanisms by which the comprehension system adjusts to this delay, the resulting costs to higher level comprehension processes, and the changes that occur in the language processing system as its familiarity with synthetic speech increases. Based on the framework we have developed, we suggest several directions for future research on the comprehension of synthetic speech.

Female↗