John M. Heinz

Cervical Auscultation Of Suckle Feeding In Newborn Infants

The authors recorded the sound signals during suckle feeding of six normal infants within the first two postnatal days. The sounds were recorded onto a cassette tape‐recorder from a small microphone attached to the infants neck, then displayed on an oscilloscope and analysed by digital signal processing techniques. These displays demonstrated acoustic patterns and temporal relationships which are not otherwise audible. The method and findings are described in detail, and the method should be useful in the clinical investigation of feeding and swallowing problems associated with more subtle neurological impairment and preterm birth.

Correlation of cervical auscultation with physiological recording during suckle-feeding in newborn infants

Pharyngeal swallows during infant suckle‐feeding are associated with a characteristic sequence of sounds audible by stethoscope or by an accelerometer or microphone held over the larynx. In rhythmically feeding term‐born neonates, the delineating acoustic elements are discrete sounds which precede and succeed pharyngeal swallows. Digital signal processing shows similarities in morphological detail between the discrete sounds preceding swallows and between those succeeding swallows; those succeeding swallows are more variable in temporal relation to swallows, amplitude and morphological detail. Variations in the pattern of interswallow respiration, including apnea, are correlated with variations in the discrete sounds. Specification of physiological correlates of these internal feeding sounds increases the utility of cervical auscultation as a method of investigation and of clinical observation of feeding.

Perception of synthesized vowel pairs by normal and specifically language impaired (SLI) children.

It has been proposed that SLI children have a rapid‐rate auditory‐processing deficit, and alternatively, that they have special difficulty with signals that are low in information or degraded. In the present study, steady‐state vowel pairs, /a/–/i/ and /ae/–/eh/, were presented to 20 normal and 20 SLI children within a series of tasks, namely, discrimination, in which they had to detect change/no‐change in a series; identification where they identified stimuli presented one at a time; and sequencing, where they indicated order of presentation of paired stimuli. For both vowel pairs, short (40–5 ms) and long (240–40 ms) series were presented. It was found that the performance of the SLI children was not significantly different from the normals’ in tasks involving /a/–/i/. Both groups of children had greater difficulty with the /ae/–/eh/ than the /a/–/i/ tasks, but the SLI children showed significantly greater decrement in performance than normals for /ae/ vs /eh/. Neither group showed a significant effect of ...

Production of highly similar vowels by language‐impaired children

It has been shown that language impaired (LI) children have greater difficulty than language normal (LN) children in identifying the synthesized vowels /e/ vs /œ/, but not /open aye/ vs /i/, when the members of test pairs are of equal duration (240 to 40 ms) [R. E. Stark and J. M. Heinz, 2360 (A) (1992)]. It was concluded that, when deprived of the durational cues present in natural speech, LI children were less well able than LN to rely upon subtle spectral cues. In the present study, children in both groups (11 LI, 9 LN) were asked to imitate the synthesized vowels /e/ and /œ/. Their responses were recorded, transcribed, and submitted to spectral analysis. Responses of individual children that were given to either /e/ or /œ/ were scored as correct, those that were given to both vowels indiscriminately were not. The scores of the two groups were not significantly different. However, the LI children’s responses were transcribed as more variable, and occupied a greater range within F1−F2 plots, than those ...

Processing of stop‐vowel syllables by normal and language‐impaired children

It has been claimed that language‐learning disordered children have impaired rapid‐rate auditory processing. One manifestation is the failure to identify stop‐vowel syllables; another less fine‐grained discrimination of stop‐vowel syllables. In the present study, 20 language‐impaired (LI) and 20 normal (LN) children (6 to 10 years) attempted to identify /ba/–/da/ syllables within an adaptive paradigm. When they failed to do so, they were given a change/no change discrimination task with these stimuli. Formant transition duration (FTD) ranged from 80 to 40 ms. The syllable pairs had either five or two formants. As in previous studies, LI children failed the identification task, even for syllables of 80‐ms FTD, significantly more often than LN. They were able to discriminate the syllables. Number of formants was not a significant variable. A subgroup of LI and LN children were subsequently asked to produce the test syllables. In both groups, children unable to produce the syllables had difficulty in identif...

Influence of contralateral noise stimulation on wave I of the ABR, elicited with condensation and rarefaction clicks in humans

Sound‐evoked efferent effects can be examined by comparing the response amplitudes of the auditory nerve with and without contralateral stimulation. It has been suggested that the efferent system modifies the mechanical characteristics of the cochlear partition by varying outer hair cell tonus and regulating the mean position of the basilar membrane [E. L. LePage, Hear. Res. 38, 177–198 (1989)]. If this is the case, the effect of contralateral stimulation may be different for responses elicited with clicks of opposite polarity (condensation versus rarefaction), as such stimuli cause initial movement of the basilar membrane either toward scala tympani or scala vestibuli. Furthermore, such stimuli are known to elicit dissimilar ABR waveforms [V. Rawool and S. Zerlin, Stand. Audiol. 17 (1988)]. Results of the surface recorded wave of the ABR obtained from human subjects, with and without contralateral noise, for rarefaction and condensation clicks as well as the possible underlying mechanisms will be presented.

Acquisition of pitch contours by infants

It has been suggested that infants may acquire control of pitch contour in their vocal productions according to an invariant schedule. The present study was designed to examine pitch contours in the vocalizations of infants in the first eighteen months of life. Eight to ten infants were recorded on a limited longitudinal basis, i.e., across each of the following are ranges: 2–10, 12–23, 26–36, 40–55, and 72–88 weeks (45 infants in all). Forty to fifty vocalizations were selected randomly from each infants output at the first and the last of these recordings. These vocalizations were analyzed acoustically by means of computer‐assisted spectral analyses and pitch extraction program. Pitch contours were categorized according to the range in which they occurred, as well as their falling/rising characteristics. Developmental differences were documented with respect to pitch contour types across age levels. However, significant differences among infants within age levels were also found. The results suggest th...

Effects of frequency modulation on absolute, masked, and reflex thresholds

Behavioral and acoustic reflex thresholds were determined for five normal-hearing subjects in response to carrier signals of 500 and 2000 Hz which were unmodulated or modulated sinusoidally at rates of 2, 20, and 200 times per second with frequency deviations (delta f) of 30, 100, and 300 Hz. Behavioral (absolute and masked) thresholds were determined using an adaptive two-alternative forced-choice procedure. Acoustic reflex thresholds were determined by visual inspection of stored reflex waveforms. Frequency modulation was not found to exert a systematic effect at absolute threshold. Frequency modulation did affect threshold estimates systematically, but differentially, at masked threshold and acoustic reflex threshold. Increasing the frequency deviation of the modulation was associated with an increase in masked threshold and with a decrease in acoustic reflex threshold at both test frequencies. The findings are discussed in terms of critical band phenomena.

Features of infant vocalization at successive age levels

It has been suggested that speech motor abilities in infants emerge within an invariant sequence of levels. The present study was designed to describe the articulatory‐acoustic features of infant vocalization and thus, to identify those that may be characteristic of infant utterances at different age levels or developmental levels. The vocalizations of five infants were studied on a limited longitudinal basis. The age ranges of these infants were 2–10, 12–23, 26–36, 40–55, and 72–88 weeks, respectively. Forty to 50 vocalizations were selected randomly from each infants output at the first and at the last recording session for a total of ten recordings. These vocalizations were analyzed acoustically by means of computer‐assisted spectral analyses. Measurements of duration and frequency were made from the resulting displays, which also provided information to listeners as they judged voicing and vocalic and consonantal features. Analyses of these preliminary data suggest that three classes of features may ...

Acoustic analysis of cry of SIDS infants

Spontaneous cry recordings were obtained for approximately 1700 infants born at the University of Maryland Hospital over a 212‐year period. Where possible, recordings were obtained during both the first and fourth weeks of life. Of those infants recorded, four later died of SIDS. For one, recordings had been obtained during both the first and fourth weeks, for one only during the first week, for one only during the fourth week, and one only at two later times (9 and 14 weeks). Thirty‐second samples of continuous, fully developed cry were selected for detailed analysis from each of the SIDS infants and from 50 age‐matched controls. For each cry segment, measures of duration, intensity, and fundamental frequency were obtained and the presence or absence of a number of cry features was determined. Preliminary analysis of the data for the two SIDS infants recorded in week one indicates that a number of the measures group toward the tails of the distributions of these measures for the controls, while the data ...