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Biomedical subjects

H R Bauer

Publications and source records attributed to H R Bauer.

11 recordsLinked to original sources
PubMed1991

Speech and language production at age 2: evidence for tradeoffs between linguistic and phonetic processing.

The purpose of this study was to explore how 2-year-old children manage the relationship between phonetic production and production of word combinations in their spontaneous speech. The subjects were 5 normally developing 2-year-olds who were participants in an ongoing longitudinal study of speech and language acquisition. Three measures were used to estimate phonetic production skills in the children's spontaneous speech samples. These included a measure of the accuracy of consonant production (Percentage of Consonants Correct), and two estimators of phonetic complexity (phonetic products for utterance and word length units). Regression analyses were used to determine the relationship between complexity of word combinations, as measured by length of utterance in morphemes and a propositional complexity analysis, and utilization of phonetic production skills. The results revealed modest tradeoffs between complexity of word combinations and accuracy of consonant production for 2 of the 5 children. The results also showed tradeoffs between complexity of word combinations and phonetic complexity of individual lexical items (phonetic product for words) for 4 of the 5 children. As the complexity of these 4 children's multiword combinations increased, the phonetic complexity of individual lexical items decreased. These results are consistent with synergistic theories of language acquisition and language processing that emphasize dynamic tradeoffs in interactions among language processing levels in a limited capacity production system.

Child Language↗
PubMed1990

Symmetry and quasi-symmetry: an example in modelling pairs of sounds from children's early speech.

The models of symmetry and quasi-symmetry may have use in the analysis of categorical data in square tables where the row and column classifications are the same. Under the model of symmetry, the probability that an observation falls in, say, the (i,j) cell of a square table is the same as the probability that it falls in the (j,i) cell. The model of symmetry requires that the expected marginal total for any one row of the table be the same as the expected marginal total for the corresponding column. The model of quasi-symmetry, which is a generalization of the model of symmetry, does not require this equality of expected row and column totals. In this paper, we illustrate the use of the models of symmetry and quasi-symmetry in the analysis of categorical data that summarize pairs of sounds in infants' and toddlers' early utterances. In the past, the complexity of infants' early vocalizations has been difficult to measure because of a lack of methods to quantify prelinguistic phonetic variables. We use the models of symmetry and quasi-symmetry as a first attempt to quantify the complexity of infants' early speech. We hope that the discovery of models appropriate for quantification of language development in normal children will have later use in identification of children at risk for communicative disorders.

Child, Preschool↗
PubMed1989

Conspecific screams and laughter: cardiac and behavioral reactions of infant chimpanzees.

The present study examined cardiac and behavioral reactions of infant chimpanzees to white noise and to conspecific screams and laughter. Chimpanzee screams evoked typical deceleratory cardiac orienting responses. Analysis of stimulus-evoked changes in respiratory sinus arrhythmia suggested that this cardiac deceleration arose from an increase in parasympathetic activity. In contrast, chimpanzee laughter evoked notable cardiac acceleration. Laughter also evoked vocalizations from the infant subjects, which were reminiscent of adult threat-barks. Analysis of respiratory sinus arrhythmia suggested that the cardioacceleratory response likely resulted from sympathetic activation, and was not associated with an inhibition of parasympathetic activity. The autonomic and vocal responses to laughter emerged early in development, were minimally dependent on social contact with adults, and declined in magnitude with increasing age. A consideration of the phylogeny of laughter raised the possibility that the functional reaction to this vocalization may be related to its origin in more primitive agonistic facio-vocal signals.

Animals↗
PubMed1987

Acoustic analyses of infant fricative and trill vocalizations.

Closants, or consonantlike sounds in infant vocalizations, were described acoustically using 16-kHz spectrograms and LPC or FFT analyses based on waveforms sampled at 20 or 40 kHz. The two major closant types studied were fricatives and trills. Compared to similar fricative sounds in adult speech, the fricative sounds of the 3-, 6-, 9-, and 12-month-old infants had primary spectral components at higher frequencies, i.e., to and above 14 kHz. Trill rate varied from 16-180 Hz with a mean of about 100, approximately four times the mean trill rate reported for adult talkers. Acoustic features are described for various places of articulation for fricatives and trills. The discussion of the data emphasizes dimensions of acoustic contrast that appear in infant vocalizations during the first year of life, and implications of the spectral data for auditory and motor self-stimulation by normal-hearing and hearing-impaired infants.

Humans↗
PubMed1987

Frequency code: orofacial correlates of fundamental frequency.

In the human voice, lip retraction as in smiling can be associated with high fundamental (Fo) and formant frequencies. The aim of this study was to investigate under naturalistic conditions the cross-species generality of the frequency code hypothesis and related orofacial correlates in Fo. Digital spectral, spectrographic, and cinegraphic measurements were made of spontaneous chimpanzee vocalizations and orofacial movements produced and recorded in the field. A significant decline in Fo was found in submissive-scream-to-aggressive-waahbark transitions as predicted by the frequency code. Teeth and lip opening distances during sounds were positively correlated with their duration, Fo, frequency rise and tempo. These positive correlates and a trivariate regression between orofacial opening and Fo give support to the coordination of these appeasing facial and vocal features proposed in the frequency code hypothesis.

Acoustics↗