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Biomedical subjects

D K Oller

Publications and source records attributed to D K Oller.

At least 55 records · Page 3Linked to original sources
PubMed1984

Tactual perception of speech-like stimuli with an electrocutaneous vocoder.

A deficiency in current tactual vocoder designs is the relatively poor transmission of rapid spectral changes (formant transitions). To understand better the application of electrocutaneous tactual stimulation as a basis for an artificial hearing system, the tactual discrimination of rapidly changing patterns was studied. Stimuli were presented on a belt containing 32 electrodes that was worn in a linear array 5 cm above the navel. Bipolar pulse trains (height 10 mA; width 13 microseconds) of specified frequencies (200, 400, or 1,000 Hz) were presented sequentially to adjacent electrodes to simulate a tactual vocoder equivalent of simple frequency transitions. Discrimination of the direction of stimulation movement (i.e., stimulation on the belt to either a subject's left or right) was assessed with one experienced subject as a function of both electrode number (four or eight electrodes) and stimulation frequency. Identification of the direction of stimulation movement was influenced both by the number of stimulus channels and by the frequency of electrocutaneous stimulation. These preliminary results indicate that the discrimination of formant trajectory transmitted in an electrocutaneous vocoder scheme is within the temporal limits typically imposed by natural speech.

Adult↗
PubMed1984

The discrimination of vowel duration by infants.

Three groups of nine 5-11-month-old infants provided evidence of discrimination of speechlike stimuli differing only in vowel duration. Ease of discrimination was directly related to the magnitude of the ratio of the longer to shorter vowel. Group one infants discriminated three vowel duration contrasts (with ratios of 0.33, 0.67, and 1.0) embedded in a synthetic [mad] syllable; group two discriminated these same duration contrasts within the bisyllable [ samad ], and group three in the trisyllable [ masamad ]. In all cases, the contrasting durations were carried by the last vowel of the synthetic word. These same three infant groups failed to provide evidence of discrimination of a final position released stop consonant contrast ([mat] versus [mad]) cued by voice excitation during closure of the [d] and not the [t]. These results suggest that vowel duration may be a primary cue for infants' perception of the voicing of final position stop consonants.

Adult↗
PubMed1984

Infants' discrimination of intensity variation in multisyllabic stimuli.

Two groups of 5- to 11-month-old infants were tested for their ability to discriminate within-utterance intensity variations similar to those associated with linguistic stress. A visually reinforced discrimination procedure was used to determine sensitivity to increments in peak intensity for a final position, synthetic CVC syllable within either a bisyllabic (CVCVC) or a trisyllablic (CVCVCVC) context. Discrimination performance was above chance for a 2-dB increment, and improved for 4- and 6-dB increments. In addition, infants were more sensitive to intensity increments in the bisyllablic as compared to the trisyllabic context. Infant sensitivity for within-utterance intensity variations is sufficient for the detection of some linguistic stress contrasts.

Cues↗
PubMed1983

Speech identification in Spanish- and English-learning 2-year-olds.

English- and Spanish-learning 2-year-olds were tested for speech skills in a real speech context. Each child was tested in his/her native language on one native and one nonnative contrast. The nonnative contrast consisted of a real native word paired with a nonsense word containing a nonnative element. The native contrast consisted of a native word paired with a nonsense word containing a minimally paired native element. The results showed that both groups of children found identification of native contrasts much easier than identification of nonnative contrasts. The results suggest that by age 2, normal children may have achieved an awareness of their native phonology, an awareness that encourages them to ignore certain distinctions that are not part of their language's contrastive meaning system.

Child, Preschool↗
PubMed1981

Linguistic pragmatics and language intervention strategies.

The recent research focus on pragmatics leads to the consideration of issues of language use that have fundamental practical implications for language assessment and intervention. Specifically, the pragmatic orientation suggests changes in the content of language assessments, by evaluating various communicative functions the child expresses, and modifications in the process of language assessment, by encouraging both the initiating and responding dimensions of the child's communicative behavior. Furthermore, the pragmatic focus suggests changes in the process of intervention. The primary goal of intervention becomes facilitation of generalized communicative functions for which syntactic structures and semantic content are only the tools. And the pragmatic framework suggests guidelines for what constitute appropriate reinforcers that sustain rather than interrupt communicative interactions.

Child↗
PubMed1981

A comparative study of pre-meaningful vocalizations produced by normally developing and Down's syndrome infants.

Pre-meaningful vocalizations produced by nine normally developing and 10 Down's syndrome infants were recorded as part of a longitudinal study of language development. The recordings were phonetically transcribed using a modified version of the International Phonetic Alphabet. Data were analyzed in terms of (1) age at onset of reduplicated babbling (2) developmental trends for place of consonant articulation, and (3) developmental aspects of vocalic productions. In general, substantial similarities between the two groups of infants were observed with regard to the selected parameters. Both groups began to produce canonical, reduplicated babbling at 8-8 1/2 months of age, and trends regarding consonantal and vocalic development for the two groups were very similar during approximately the first 15 months of life.

Age Factors↗
PubMed1981

Discrimination of voice onset time in infancy.

In an effort to determine whether infants can discriminate speech sounds on the basis of a single acoustic cue, timing onset of periodic voicing, two experiments were conducted employing synthetic speech sounds. Naturally produced syllable pairs were also used for comparison. In the first experiment infants evidenced discrimination of a naturally produced /ba/ versus /pa/ pair and a naturally /du/ versus /tu/ pair. In addition, infants discriminated a synthetic /ba/ versus /pa/ contrast that was cued by several acoustic differences in addition to timing onset of periodic voicing but failed to evidence an ability to discriminate a synthetic /du/ versus /tu/ contrast that contained flat first formants and differed only in timing onset of periodic voicing. A second experiment was conducted in which infants once again evidenced discrimination of naturally produced /du/ versus /tu/ stimuli but not of synthetic /du/ versus /tu/ stimuli containing slight first-formant transitions. These results suggest that timing onset of periodic voicing alone may not be a sufficient cue for infant discrimination of English voicing contrasts.

Acoustic Stimulation↗
PubMed1980

A comparative study of speech perception in young severely retarded children and normally developing infants.

The discrimination of minimally paired speech sounds by seven retarded children with a mean age of 3 years, 2 months and a mean IQ of 38.4 was compared with the discrimination performance of eight normally developing 7-month-old infants. Children and infants were tested using the Visually Reinforced Infant Speech Discrimination (VRISD) paradigm in which they were taught to respond with a head turn to a change in a repeating background auditory stimulus. Responses were reinforced by activation of an animated toy. All children proved to be conditionable and both groups evidenced discrimination of the speech contrasts tested. The data suggest that the retarded children have moree difficulty processing a contrast cued by rapid spectral changes (often associated with consonant discrimination) than they do a contrast cued by steady-state spectral information (often associated with the perception of slowly articulated vowels). The normally developing infants did not find rapid spectral cues mor difficult than steady-state cues These results parallel those of Tallal (1976) who found that dynamic cues were specifically difficult for dysphasic children (with normal nonverbal intelligence), but not for linguistically-normal elementary school children.

Child, Preschool↗
PubMed1980

Tactual speech perception by minimally trained deaf subjects.

Research on tactual perception of speech has shown that many phonetic contrasts can be transmitted to the deaf through artificial hearing devices that stimulate the sense of touch. Past research has emphasized long-term training with tactual reception for the achievement of maximal perceptual performance. The present study demonstrates that, with a brief training period, deaf adolescents can attain a high level of perceptual performance with a tactual speech system in discrimination of certain hard-to-lipread word pairs pronounced by both a male and female speaker. Thus some speech sounds previously indistinguishable by the deaf people can be immediately available for speech comprehension through the tactual vocoder; and other speech sounds will be recognized with further training. The reason that some contrasts are learned quickly and others require extensive training may be found in a pattern perception postulate proposed by Gavin (1979): word patterns that result in stimulation across a greater area of skin tend to be more discriminable than word patterns which stimulate only small areas of the skin.

Adolescent↗
PubMed1978

The relatedness of phonological processes of a hearing-impaired child.

This is a study, in the generative framework, of the phonology of a 6-year-old, hard-of-hearing child. The study has two main results: (1) the phonological substitutions and delections of this hearing imparied child are basically the same in kind as those found in the speech of younger normals and (2) the phonological processes of the child's system fit into groups of processes, each group operationalizing some phonetic preference of the child. Implications for a general theory of phonologica acquistion are discussed.

Age Factors↗
PubMed1977

Effect of final-syllable position on vowel duration in infant babbling.

Previous research has suggested possible speech-production- and/or speech-perception-oriented causes for the temporal phenomenon referred to as final-syllable vowel lengthening, yet little conclusive evidence has been adduced for either possibility. The present study represents an attempt to provide additional information concerning the nature of this phenomenon by approaching the issue from a developmental perspective. A much smaller amount of final-syllable vowel lengthening was observed in the premeaningful vocalizations of a number of very young infants than in phonetically comparable utterances produced by adult speakers of English. It is concluded on the basis of this preliminary evidence that extensive final-syllable lengthening observed in the productions of adult speakers of English seemingly constitutes a learned behavior.

Auditory Perception↗