Harold R. Bauer

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.

The ethologic model of phonetic development: I. Phonetic contrast estimators

This study defines phonetic product estimators of an ethologic model of phonetic contrast development and introduces some of their properties with the use of simulations. The model of phonetic development is presented in the behavioural biology tradition of ethology that includes a series of naturalistic and computational studies of childrens phonetic development. Six children interacting with their mothers were studied from one to two years of age to discover patterns of emergence in phonetic and language development.Phonetic contrast is a key concept in the model and studies. Phonetic contrast refers to the ability to use different articulatory movements variably in time, a necessary skill for language acquisition. Children are hypothesized to have limited expressive resources for this ability to produce phonetically contrastive utterances which emerge into later language skills.The aim of these studies is to state and test different phonetic product model estimators of the role of phonetic contrast in...

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.

A comparative study of common chimpanzee and human infant sounds

Chimpanzees observed in Tanzania produced a graded, dynamic sound system ranging from short distance, softer, lower F0 sounds to long distance, louder, higher F0 sounds. A softer and a louder sound category, the whimper and the scream, were selected for further study of F0 and harmonics. From these acoustic analyses and behavioral observations, evidence for a variety of phonatory and resonance patterns were evident in their vocalic sound system which could carry information but lack the segmental contrastivity of human speech. Human infants about a year old were audio and video recorded in the laboratory or home. Vocalic sound durations, F0 contours, and range were much more variable than those observed for chimpanzees. The F0 of human infant sounds often ranged from 300–600 Hz, although occasionally F0 values many times higher were produced making harmonic‐formant interactions a critical issue in the comparison with chimpanzee sounds. Fricative, stop, and other consonants not evident in chimpanzee sounds...

Toward an acoustic typology of vocalizations in the first year of life

Acoustic methods have been applied sufficiently to the study of infant vocalizations in the first year of life that an acoustic data base has begun to emerge in the literature. This paper considers this data base with respect to (1) its adequacy in describing the pattern of normal phonetic development, and (2) its potential for identification of infants at risk for communication disorder. With respect to (1) above, data will be summarized on several acoustic variables, including vocalic formant frequencies, utterance duration, fundamental frequency, vocal tremor frequency, noise spectra of fricative and trill segments, repetition rate of trills, and voice onset time for syllable‐initial stops. With respect to impairment or palatal clefting. A preliminary acoustic typology based on an acoustic coding of infant vocalizations will be presented.

Acoustic‐phonetic correlates of language development

Phonetic contrast has been suggested as a cognitive operating principle underlying the continuity of infant phonetic development [H. R. Bauer, J. Acoust. Soc. Am. Suppl. 1 75, S45 (1984)]. Phonetic contrast was estimated in the current study using the phonetic product (PP) estimator weighted to the same eight American English sound‐class frequencies. The PP was a result of the multiplication of the number of eight different contrasting sounds per minute after weighting and was summarized from recordings of mother‐infant interactions. The results from four children were compared when each was 1 and 2 years old. Associated measures of language development at 2 years of age were also compared for predicted order based upon the subjects 1‐year data. As an estimator of phonetic contrast, PP and its acoustic correlates in 1‐year‐old infants, were predictive of most of their PP and associated language variables at 2 years of age.

Vowel intrinsic pitch in 1‐year‐olds?

Intrinsic pitch is distinctive of human vowels in older children and adults. Because of the ontogenetic reconfiguration of the human vocal tract, the relationship between tongue height and the fundamental frequency of infant vowels remains in question. In this paper, the instrinsic pitch of high‐ versus low‐ front and back vowels was measured from 13‐month‐old infants. Six infants were recorded interacting with their mothers at home. High‐quality wireless microphone, time‐coded, 1‐h recordings were narrowly transcribed by two investigators with the aid of frequency and amplitude displays. The subsample of high and low vowels was drawn from a computerized database for acoustic analysis. Vowels were analyzed for F0 with narrow‐band spectrographs. Measurements were made from the center of each vowel and the results subjected to statistical analysis. Results were related to individual variability in infant F0 and the reconfiguration of the human infant vocal tract.

On velopharyngeal articulation in the origin of human CV contrasts

The origin of human CV contrasts from nonhuman primate sound systems is hypothesized to be, in part, dependent upon effective nasal port valving due to velopharyngeal articulation. Common chimpanzee sound acoustics and associated oral‐facial movements were studied. Compared with obstruents found in human infants, chimpanzee sounds suggest no similar post‐velum evidence of obstruent production. An ethologic model of phonetic development based upon the production of sensorimotor contrasts [Bauer, J. Acoust. Soc. Am. Suppl. 1 75, S45 (1984)] was used to detail the hypothetical phylogenetic and developmental significance of nasal port articulation in the origin of human speech sound contrasts. Consistent with the hypothesis, the lack of comparative evidence for chimpanzee post‐velum obstruent sounds supports the significance of velopharyngeal articulation in the origin of human obstruent‐vowel contrasts.

A neuroethologic hypethesis of speech development

The relation between phonetic contrast and individual differences in infants was noninvasively measured to operationally state a hypothesis of speech development. Four 13‐month‐old infants were recorded interacting with their mothers at home. Continuous f0 and amplitude displays were used in analyses made by two observers from each 1‐h, time coded session of all vocalizations. Acoustic‐phonetic data were lumped into front, central, and back vocants and bilabial, apical, palatal, and velar closants to emphasize motor contrast. These seven categories of speech sounds were graphed by each minute in the Phonetic Record, and then multiplied within each minute sample to yield a Phonetic Product, as a production/contrast measure. Individual Phonetic Record and Phonetic Product populational differences in production and contrast were found in the temporal analyses that are hypothesized to be predictive of speech‐language development. [Supported by NINCDS Grants NS 16763 and 5T32 NS 07147.]

Acoustic analyses of closant sounds in infants' comfort‐state utterances

Closants, or consonant‐like sounds, were described acoustically using 16‐kHz spectrograms and LPC or FFT analyses based on waveforms sampled at 20 or 40 kHz. The four major closant types were stops, fricatives and affricatives, vibrants or trills, and glides. Compared to similar sounds in adult speech, the closant sounds of the 3‐, 6‐, and 9‐month‐old infants had significant regions of energy in the higher frequencies, i.e., to and above 14 kHz. An infants production of closants having the same manner and place often was highly variable in spectral and temporal features, even in the case of reduplicated babbling. For example, the occurrence of stop bursts sometimes was highly variable with respect to voice onset or offset. However, there were instances of reliable reproduction of a basic sound pattern or phonetic property. Acoustic features are described for various places of articulation of stops, fricatives, and trills. The discussion of the data emphasizes (1) the major dimensions of acoustic contrast...