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Biomedical subjects

J F Kent

Publications and source records attributed to J F Kent.

At least 19 recordsLinked to original sources
PubMed2001

Clinicoanatomic studies in dysarthria: review, critique, and directions for research.

More than 30 years ago, Darley, Aronson, and Brown (1969) proposed clinicoanatomic correlations for seven perceptual types of dysarthria. These correlations have not been systematically re-examined even though imaging technologies developed in recent years provide the means to do so. This review considers data from published imaging studies as well as data from selected medical interventions to evaluate the current state of knowledge that relates lesion site to the nature of a speech disturbance. Although the extant data are not sufficient to allow a complete evaluation of the seven types of dysarthria described by Darley et al., relevant information has been reported on lesions of the pyramidal pathway, extrapyramidal pathway, and cerebellum. In general, the results are best explained by an equivalence mode of brain-behavior relationship in which a type of dysarthria is associated with a lesion in one of two or more brain structures. Criteria also are proposed for future studies of clinicoanatomic relationships in neurogenic communication disorders.

Brain↗
PubMed2000

Ataxic dysarthria.

Although ataxic dysarthria has been studied with various methods in several languages, questions remain concerning which features of the disorder are most consistent, which speaking tasks are most sensitive to the disorder, and whether the different speech production subsystems are uniformly affected. Perceptual and acoustic data were obtained from 14 individuals (seven men, seven women) with ataxic dysarthria for several speaking tasks, including sustained vowel phonation, syllable repetition, sentence recitation, and conversation. Multidimensional acoustic analyses of sustained vowel phonation showed that the largest and most frequent abnormality for both men and women was a long-term variability of fundamental frequency. Other measures with a high frequency of abnormality were shimmer and peak amplitude variation (for both sexes) and jitter (for women). Syllable alternating motion rate (AMR) was typically slow and irregular in its temporal pattern. In addition, the energy maxima and minima often were highly variable across repeated syllables, and this variability is thought to reflect poorly coordinated respiratory function and inadequate articulatory/voicing control. Syllable rates tended to be slower for sentence recitation and conversation than for AMR, but the three rates were highly similar. Formant-frequency ranges during sentence production were essentially normal, showing that articulatory hypometria is not a pervasive problem. Conversational samples varied considerably across subjects in intelligibility and number of words/ morphemes in a breath group. Qualitative analyses of unintelligible episodes in conversation showed that these samples generally had a fairly well-defined syllable pattern but subjects differed in the degree to which the acoustic contrasts typical of consonant and vowel sequences were maintained. For some individuals, an intelligibility deficit occurred in the face of highly distinctive (and contrastive) acoustic patterns.

Adolescent↗
PubMed1997

A speaking task analysis of the dysarthria in cerebellar disease.

Cerebellar disease affects a number of skilled movements, including those in speech. Ataxic dysarthria, the speech disorder that typically accompanies cerebellar disease, was studied by acoustic methods. Control subjects and subjects with ataxic dysarthria were recorded while performing a number of speaking tasks, including sustained vowel phonation, syllable repetition, monosyllabic word production (intelligibility test), sentence recitation, and conversation. Acoustic data derived from the speech samples confirmed the hypothesis that temporal dysregulation is a primary component of the speech disorder. The data also show that the nature of the disorder varies with the speaking task. This result agrees with observations on other motor systems in subjects with cerebellar disease and may be evidence of a dissociation of impairments. Suggestions are offered on the selection of measures for a given task and on the role of the cerebellum in the regulation of speaking.

Adult↗
PubMed1995

The United States Air force optometry residency program.

The USAF Optometry Residency Program promotes an educational climate that facilitates the education and development of the resident doctor not only as an optometrist but also as a military officer. Development of self-directed education and decision making within the training period is emphasized. Residents are encouraged to examine and challenge existing ideas and to develop physiological concepts and principles so the practical application of these skills is reflected in active clinical practice and effective professional relationships. The Air Force Optometry Residency Program will train career-oriented Air Force optometrists in advanced clinical and diagnostic techniques, aerospace optometry, and clinic management including the latest continuous quality improvement concepts. Recent changes have enlarged the scope of practice for Air Force optometrists. This expanded scope of practice has created a need for a nucleus of residency-trained optometrists, skilled in the latest techniques of eye care, who return to the field and train their associates in these advanced techniques. Over 40 percent of Air Force optometry clinics are manned by one doctor of optometry. Residency-trained optometrists are able to provide a high level of comprehensive optometric care at these facilities. Through this program the Air Force can keep pace with the evolution of optometry and meet the challenge of providing the highest quality care to our patients.

Aerospace Medicine↗
PubMed1992

Quantitative description of the dysarthria in women with amyotrophic lateral sclerosis.

Speech intelligibility and its phonetic and acoustic correlates were studied in a group of 10 women with amyotrophic lateral sclerosis (ALS). Intelligibility assessment with a word-identification test indicated that the most disrupted phonetic features pertained to velopharyngeal valving, lingual function for consonant contrasts of place and manner, and syllable shape. An acoustic signature analysis based on trajectories of the first and second formants in selected monosyllabic test words revealed that the mean slope of the second formant (F2) was reduced compared with that of a normal geriatric control group. This F2 slope reduction is interpreted to reflect loss of lingual motoneurons. Acoustic measures of phonatory function for sustained vowel prolongation demonstrated abnormalities in fundamental frequency, perturbations of frequency (jitter) and amplitude (shimmer), and signal-to-noise ratio. The data for women with ALS are compared with data for a normal geriatric control group of women and with data for a group of 25 men with ALS (Kent et al., 1990). Although the overall ranking of errors was similar for males and females with ALS, men were more likely to have impairments of voicing in syllable-initial position.

Adult↗
PubMed1992

Formant trajectory characteristics of males with amyotrophic lateral sclerosis.

The purpose of this study was to describe the formant trajectories produced by males with amyotrophic lateral sclerosis (ALS), a degenerative neuromuscular disease that is typically associated with dysarthria. Formant trajectories of 25 males with ALS and 15 neurologically normal geriatric males were compared for 12 words selected from the speech intelligibility task developed by Kent et al. [J. Speech. Hear. Disord. 54, 482-499 (1989)]. The results indicated that speakers with ALS (1) produced formant transitions having shallower slopes than transitions of normal speakers, (2) tended to produce exaggerations of formant trajectories at the onset of vocalic nuclei, and (3) had greater interspeaker variability of formant transition characteristics than normal speakers. Within the group of ALS speakers, those subjects who were less than 70% intelligible produced distinctly more aberrant trajectory characteristics than subjects who were more than 70% intelligible. ALS subjects who were less than 70% intelligible produced many trajectories that were essentially flat, or that had very shallow slopes. These results are discussed in terms of the speech production deficit in the dysarthria associated with ALS, and with respect to the potential influence of aberrant trajectories on speech intelligibility.

Adult↗
PubMed1992

Prescribing spectacles for aviators: USAF experience.

This special report was written for USAF vision specialists to use as a guide when prescribing spectacles for military aviators and to extend to the civilian sector the knowledge gained from the USAF experience. Visual correction in aviators presents some unique problems, especially for presbyopes. The demands of each individual aircraft environment need to be well understood. Ophthalmologists and optometrists must consider all pertinent aeromedical factors before prescribing spectacles for ametropic aviators.

Adult↗
PubMed1991

Speech deterioration in amyotrophic lateral sclerosis: a case study.

Few detailed reports have been published on the nature of speech and voice changes during the course of amyotrophic lateral sclerosis (ALS). The subject of this case study is a woman who was diagnosed as having ALS with bulbar signs at the age of 53. Speech intelligibility, pulmonary function, and selected speech and voice functions were tested during an approximately 2-year course of her disease. Over this period, her speech intelligibility, as measured by a multiple-choice word identification test, declined from 98% to 48%. Phonetic features that were most affected during the intelligibility decline included voicing contrast for syllable-initial and syllable-final consonants, place of articulation contrasts for lingual consonants, manner of articulation for lingual consonants, stop versus nasal manner of production, features related to the liquid consonants, and various features related to syllable shape. An acoustic measure, average slope of the second-formant frequency, declined in association with the intelligibility reduction and is thought to reflect the loss of lingual motoneurons. Her pulmonary function also declined over the observation interval, with particularly severe reduction in measures of air flow. Oral diadochokinesis and measures of vocal function (including jitter, shimmer, and signal-to-noise ratio) were highly variable across test sessions. These results are discussed in terms of the challenges they present to sensitive assessment of change and to management of the communication disability in ALS.

Amyotrophic Lateral Sclerosis↗
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↗
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↗
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↗
PubMedDate not supplied

Voice dysfunction in dysarthria: application of the Multi-Dimensional Voice Program.

Phonatory dysfunction is a frequent component of dysarthria and often is a primary feature noted in clinical assessment. But the vocal impairment can be difficult to assess because (a). the analysis of voice disorder of any kind can be challenging, and (b). the voice disorder in dysarthria often occurs along with other impairments affecting articulation, resonance, and respiration. A promising assessment tool is multi-parameter acoustic analysis, such as the Multi-Dimensional Voice Program (MDVP). Part 1 of this paper recommends procedures and standards for the acoustic analysis of voice, including (1). selection of the sample to be analyzed, (2). signal quality requirements, (3). availability of normative data for both genders and different ages of speakers, (4). reliability of analysis, and (5). correlation of acoustic results with results from other methods of analysis. In Part 2, acoustic data are reviewed for the dysarthria associated with Parkinson disease (PD), cerebellar disease, amyotrophic lateral sclerosis (ALS), traumatic brain injury (TBI), unilateral hemispheric stroke, and essential tremor. Tentative profiles of voice disorder are described for these conditions. These profiles may serve as hypotheses for future research. Although several issues remain to be resolved in the acoustic analysis of voice disorder in dysarthria, steps can be taken now to promote the reliability, validity, and clinical utility of such analyses. (1). As a result of this activity, the participant will be able to describe ways in which an optimal multi-dimensional analysis of voice can be performed with modern acoustic analysis systems. (2). As a result of this activity, the participant will be able to apply multi-dimensional acoustic analysis of voice to individuals who have a dysarthria-related voice disorder. (3). As a result of this activity, the participant will be able to identify major sources of normative data on the Multi-Dimensional Voice Program.

Amyotrophic Lateral Sclerosis↗
PubMedDate not supplied

Acoustic studies of dysarthric speech: methods, progress, and potential.

EDUCATIONAL OBJECTIVES: (1) The reader will be able to describe the major types of acoustic analysis available for the study of speech, (2) specify the components needed for a modern speech analysis laboratory, including equipment for recording and analysis, and (3) list possible measurements for various aspects of phonation, articulation and resonance, as they might be manifest in neurologically disordered speech.

Dysarthria↗
PubMedDate not supplied

Task-based profiles of the dysarthrias.

The dysarthrias are associated with a variety of motor disturbances distributed over several motor systems of speech production. The features of a given dysarthria often vary with the speaking task, and this task-dependency affords insights into the responsible neural lesion and its effects on the motor regulation of speech. Each task also is amenable to quantitative analyses with acoustic or physiologic methods, and these analyses may redefine the value of these speaking tasks. This article considers task-based analyses for the dysarthrias associated with Parkinson's disease, cerebellar disease, and stroke.

Brain Infarction↗
PubMedDate not supplied

Effect of speaking rate manipulations on acoustic and perceptual aspects of the dysarthria in amyotrophic lateral sclerosis.

The current study explored the acoustic and perceptual effects of speaking rate adjustments in persons with amyotrophic lateral sclerosis (ALS) and in neurologically normal individuals. Sentence utterances were obtained from the participants at two self-selected speaking rates: habitual and fast. Total utterance durations, segment durations, and vowel formant frequencies comprised the acoustic measures, whereas magnitude estimates of speech intelligibility and severity of speech involvement were the perceptual measures. Results showed that participants in both the neurologically normal and ALS groups were able to increase their speaking rate when asked to do so, but that the participants with ALS were significantly slower than the neurologically normal participants at both rates. Both groups of participants also showed compression of the acoustic vowel space with increased speaking rate, with the vowel spaces of participants with ALS generally being more compressed than the vowel spaces of neurologically normal participants, at either rate. Most importantly, the perceptual measures failed to show any effect of the speaking rate adjustment on scaled intelligibility or severity, for either group. These findings are discussed relative to the general issue of slow habitual speaking rates among many speakers with dysarthria, and possible explanations for the slowness. The lack of an effect of increased rate on the perception of the speech deficit among speakers with ALS argues against the idea that the habitually slow rates are a form of compensation to reduce the complexity of speech production.

Aged↗