Search PubMed⌕ Search

Biomedical subjects

R D Kent

Publications and source records attributed to R D Kent.

At least 37 records · Page 2Linked to original sources
PubMed1990

Impairment of speech intelligibility in men with amyotrophic lateral sclerosis.

Speech intelligibility was studied in a group of 25 male patients with amyotrophic lateral sclerosis (ALS). The object of the study was to determine the phonetic impairments underlying the speech intelligibility deficits that frequently accompany ALS. Analyses with a word intelligibility test indicated that the most disrupted phonetic features involved phonatory (voicing contrast) function, velopharyngeal valving, place and manner of articulation for lingual consonants, and regulation of tongue height for vowels. The mean error proportion for the five most severely affected features correlated highly (0.97) with the intelligibility score (percent correct). The phonetic feature analyses are one index of bulbar muscle impairment in amyotrophic lateral sclerosis and also may help to direct the speech management in these individuals.

Adult↗
PubMed1990

Speech analysis systems: a survey.

Recently developed, relatively inexpensive systems make digital speech analysis available to many teachers, clinicians, and researchers who have not had access to previous systems. Addressing these prospective users, we survey five microcomputer programs and two dedicated devices for recording, editing, and analyzing speech. We review the capabilities, requirements, and user interface of each system. We recommend considerations for prospective users and for developers of the next generation of such programs and devices. Finally, we briefly survey seven additional systems.

Computers↗
PubMed1989

Toward phonetic intelligibility testing in dysarthria.

The measurement of intelligibility in dysarthric individuals is a major concern in clinical assessment and management and in research on dysarthria. The measurement objective is complicated by the fact that intelligibility is not an absolute quantity but rather a relative quantity that depends on variables such as test material, personnel, training, test procedures, and state of the speaker. This paper reviews scaling procedures and item identification tests as they have been applied to dysarthric speech. Based in part on previous studies of speech of the hearing impaired, a profile has been designed to direct research on the acoustic or physiologic correlates of dysarthric intelligibility impairment. In addition, a word intelligibility test is proposed for use with dysarthric speakers. This test is designed to examine 19 acoustic-phonetic contrasts that are likely to (a) be sensitive to dysarthric impairment and (b) contribute significantly to speech intelligibility. Preliminary data from a sample of subjects with amyotrophic lateral sclerosis are presented to illustrate the use of this test in the phonetic interpretation of intelligibility impairment.

Adult↗
PubMed1988

The acoustic signature for intelligibility test words.

As part of a research program that aims to develop an explicit acoustic basis for a single-word intelligibility test, an initial attempt to characterize the formant trajectories and segment durations of seven test words produced by 30 normal speakers is described. These characterizations are referred to as "acoustic signatures." The data indicate that: (1) formant trajectories show two sex effects, namely, that females are more variable as a group than males and tend to have greater slopes for the transitional segment of the second-formant trajectories and that these effects are consistent across words; (2) Bark transformations of the frequency data do not seem to eliminate the interspeaker differences in formant trajectories, nor do they eliminate either of the sex effects described above; and (3) segment durations have different variabilities depending on the syllabic structure of the word; no sex effect was noted here. The discussion focuses on the appropriate form for the acoustic signatures, as well as factors that should be considered in selecting words for signature development. To demonstrate the potential application of these data, formant trajectory and segment duration data from 18 speakers with amyotrophic lateral sclerosis and varying degrees of dysarthria are compared to the acoustic signature for the word wax.

Aged↗
PubMed1987

Phonetic development in identical twins differing in auditory function.

The subjects of this report are identical (monozygotic) twin boys who differ in auditory function. One has normal hearing; the other has a profound hearing loss bilaterally. These boys offered a rare opportunity to study the effects of hearing loss on vocal development with reasonable control over environmental and genetic factors. This initial report focuses on their vocal development over the sampled ages of 8, 12, and 15 months. Acoustic-phonetic differences in the babbling of the two boys were evident in the 8-month sample (the first recording opportunity), and some differences between them became greater over the succeeding samples at 12 and 15 months. The major differences were in the formant patterns of vocalic elements; the frequency of occurrence of fricatives, affricates, and trills; histograms of syllable type; and variation in vowel usage. The data hold implications for the early identification of infants at risk for communication disorder and for the understanding of auditory-motor processes in phonetic development during infancy.

Child Language↗
PubMed1987

Maximum performance tests of speech production.

The maximum performance tests of speech production are those tests that examine the upper limits of performance for selected speech tasks. Among the most commonly used maximum performance tests are the following: maximum duration of phonation, maximum fricative duration, maximum phonation volume, maximum expiratory pressure, fundamental frequency range, maximum sound pressure level, maximum occluding force of the articulators, and diadochokinetic (maximum repetition) rate. Many clinicians use at least some of these tasks as part of an assessment protocol. These tests are analogous to strength, range, or speed tests in clinical neurology. Given the widespread use of these tests and a rather scattered literature on normative values obtained for them, a survey of the data base seemed in order. This paper summarizes the published normative data, discusses the adequacy of these data for clinical application, and recommends interpretive guidelines to enhance the usefulness of maximum performance tests.

Humans↗
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↗
PubMed1984

Psychobiology of speech development: coemergence of language and a movement system.

Speech development in the child represents the coemergence of language and a movement system. This paper presents seven basic principles on which a theory of speech development should be formed. Briefly, these principles address developmental changes in musculoskeletal and neural anatomy, continuities in phonetic development, coordination of productive (motor) and perceptual capabilities, rhythmic or cyclic patterning of movement, changing units of phonologic contrast, and interaction of phonetic development with acquisition of a motor skill for speech. These basic principles are in harmony with an autoorganizational theory of language development in which the infant generates, maintains, and transforms patterns of order. Examples of developmental patterns are taken from the literature to illustrate the explanatory value of the autoorganizational theory.

Adult↗
PubMed1983

Acoustic patterns of apraxia of speech.

Apraxia of speech (or verbal apraxia) is a controversial disorder, considered by some to be an impairment of the motor programming of speech. Because the disorder is characterized by "higher order" errors such as metathesis and segment addition as well as by errors of apparent dyscoordination of articulation, it seems to reflect a relatively high level of damage to the nervous system. This report presents acoustic descriptions of the speech of seven persons diagnosed as having apraxia of speech but without severe aphasic impairment, especially agrammatism. The acoustic results indicate a variety of segmental and prosodic abnormalities, including slow speaking rate with prolongations of transitions, steady states, and intersyllable pauses; reduced intensity variation across syllables; slow and inaccurate movements of the articulators; incoordination of voicing with other articulations; initiation difficulties; and errors of selection or sequencing of segments. These error patterns are discussed with respect to a theory of motor control based on spatial-temporal schemata. In addition, consideration is given to the controversy about phonologic versus motor programming impairment in apraxia of speech.

Adult↗
PubMed1982

A fluent backward talker.

This report documents the ability of a man to reverse the order of segments within words, so quickly that the simultaneous translation of forward speech into reversed speech was possible. Transcriptions of recorded backward speech and several processing tasks were used to clarify this man's profile of unusual linguistic skills. Analyses of the background speech showed evidence of sensitivity to both phonemic and orthographic representations of the utterances.

Adult↗
PubMed1982

Acoustic properties of pathologic reiterative utterances: a case study of palilalia.

Acoustic analyses of the reiterative utterances of one subject demonstrate a high degree of similarity among the members of a repetition train. The acoustic data did not confirm for this patient the published description of palilalia as a reiteration of utterances in a context of increasing rate and decreasing loudness. In fact, the final utterance in a repetition train often had either a longer duration, greater intensity, or more pronounced fundamental frequency change (or any combination of these) than its predecessors. It is suggested that these may be more than one type of pathological reiterative utterance.

Adult↗
PubMed1982

Acoustic features of infant vocalic utterances at 3, 6, and 9 months.

Recordings were obtained of the comfort-state vocalizations of infants at 3, 6, and 9 months of age during a session of play and vocal interaction with the infant's mother and the experimenter. Acoustic analysis, primarily spectrography, was used to determine utterance durations, formant frequencies of vocalic utterances, patterns of f0 frequency change during vocalizations, variations in source excitation of the vocal tract, and general properties of the utterances. Most utterances had durations of less than 400 ms although occasional sounds lasted 2 s or more. An increase in the ranges of both the F1 and F2 frequencies was observed across both periods of age increase, but the center of the F1-F2 plot for the group vowels appeared to change very little. Phonatory characteristics were at least generally compatible with published descriptions of infant cry. The f0 frequency averaged 445 Hz for 3-month-olds, 450 Hz for 6-month-olds, and 415 Hz for 9-month-olds. As has been previously reported for infant cry, the vocalizations frequently were associated with tremor (vibrato), harmonic doubling, abrupt f0 shift, vocal fry (or roll), and noise segments. Thus, from a strictly acoustic perspective, early cry and the later vocalizations of cooing and babbling appear to be vocal performances in continuity. Implications of the acoustic analyses are discussed for phonetic development and speech acquisition.

Age Factors↗
PubMed1979

Isovowel lines for the evaluation of vowel formant structure in speech disorders.

This report describes a system of isovowel lines in the F1-F2 and F2-F3 planes and demonstrates how these linear approximations to vowel formant frequencies for a diverse sample of speakers can be used to evaluate the vowel formant structures of individuals with speech disorders. The application to disordered speech is illustrated with data for dysarthric adults, deaf adolescents, and young children with developmental errors of: Formula: (See Text) production.

Adolescent↗
PubMed1979

Acoustic characteristics of dysarthria associated with cerebellar disease.

The speech of five individuals with cerebellar disease and ataxic dysarthria was studied with acoustic analyses of CVC words, words of varying syllabic structure (stem, stem plus suffix, stem plus two suffixes), simple sentences, the Rainbow Passage, and conversation. The most consistent and marked abnormalities observed in spectrograms were alterations of the normal timing pattern, with prolongation of a variety of segments and a tendency toward equalized syllable durations. Vowel formant structure in the CVC words was judged to be essentially normal except for transitional segments. The greater the severity of the dysarthria, the greater the number of segments lengthened and the degree of lengthening of individual segments. The ataxic subjects were inconsistent in durational adjustments of the stem syllable as the number of syllables in a word was varied and generally made smaller reductions than normal subjects as suffixes were added. Disturbances of syllable timing frequently were accompanied by abnormal contours of fundamental frequency, particularly monotone and syllable-falling patterns. These dysprosodic aspects of ataxic dysarthria are discussed in relation to cerebellar function in motor control.

Aged↗