Biomedical subjects

K M Yorkston

Publications and source records attributed to K M Yorkston.

At least 19 recordsLinked to original sources

PubMed1994

Differential phonatory characteristics of four women with amyotrophic lateral sclerosis.

Patients with specific neural subsystem involvement are often reported to present with particular perceptual characteristics of voice. This has been true for diseases such as amyotrophic lateral sclerosis (ALS), a progressive disease in which mixed neurologic signs are present. This article reports acoustic data on the phonatory performance of four women diagnosed with ALS who had initial bulbar signs and progressive phonatory deterioration. The data presented here demonstrate that the phonatory characteristics of women with ALS are not uniform, but in fact may vary greatly from patient to patient.

Amyotrophic Lateral Sclerosis↗

PubMed1994

Effects of temporal alterations on speech intelligibility in parkinsonian dysarthria.

The effect of two types of temporal alterations, paced and synthetic, on the intelligibility of parkinsonian dysarthric speech was investigated. Six speakers with idiopathic Parkinson's disease served as subjects. Paced temporal alterations were created by slowing each speaker to 60% of his/her habitual speaking rate. The synthetic alterations were created by modifying the habitual rate speech samples using digital signal processing. Three types of synthetic alterations were examined: Pause Altered, Speech Duration Altered, and Pause and Speech Duration Altered. The 60% of habitual speaking rate condition was more intelligible than the synthetic conditions. In addition, none of the synthetic alterations were found to be more intelligible than samples produced at habitual speaking rates. The results suggest that simple alterations of speech signals do not explain the differences in intelligibility that have been observed when parkinsonian dysarthric speakers reduce speaking rates. Reasons for the failure of synthetic alterations to increase speech intelligibility scores are discussed.

Aged↗

PubMed1990

Extended communication samples of augmented communicators. I: A comparison of individualized versus standard single-word vocabularies.

Vocabulary selection for linguistically intact augmented communicators is a growing clinical concern. The purpose of this study was to compare and contrast the relative benefits of word lists that were individualized for these augmented subjects to word lists selected from standard vocabulary sources. Communication samples were collected for 14 consecutive days from 10 subjects who used augmentative and alternative communication (AAC) devices. These samples were analyzed to determine the frequency of single word occurrence, and the results were compared with those obtained from analysis of standard vocabulary lists. The conclusions of the study were (a) that when vocabulary lists are individually created, based on the frequency of word occurrence in natural communication samples, relatively short lists can represent a large proportion of the total communication sample; (b) that individualized word lists are more efficient than standard vocabulary lists, if efficiency is defined as a large proportion of the total sample represented by a small list; and (c) that if used in their entirety, standard lists are not efficient because they contain a large number of words that are rarely used.

Adolescent↗

PubMed1990

Extended communication samples of augmented communicators. II: Analysis of multiword sequences.

The three primary purposes of this project are (a) to identify those word sequences that occur frequently across a group of 10 linguistically intact augmented communicators, (b) to determine the communality with which the various augmented communicators use specific word sequences, and (c) to evaluate the usefulness of word sequences in providing keystroke savings for users of augmentative and alternative communication (AAC) devices as compared to letter-by-letter spelling or single-word retrieval. Communication samples were collected for 14 consecutive days from 10 subjects who used AAC devices. These samples were analyzed with custom software to determine the frequency of occurrence of one-, two-, three-, four-, and five-word sequences. The results revealed that three-, four-, and five-word sequences occurred very infrequently within and across communication samples. Two-word sequences occurred much more frequently than the longer sequences. The authors concluded that clinicians should continue to encourage linguistically intact clients to select long messages (three words or more) for their AAC devices based on message content and the urgency with which messages need to be delivered rather than relying exclusively on statistical analysis. However, statistically based multiword analysis should not be abandoned. Frequently occurring one- and two-word sequences may be an important source of messages that will increase communication efficiency when stored and retrieved in an AAC device.

Adolescent↗

PubMed1990

The effect of rate control on the intelligibility and naturalness of dysarthric speech.

Speaking rates of individuals with severe ataxic dysarthria (n = 4) and severe hypokinetic dysarthria (n = 4) were reduced to 60% and 80% of habitual rates using four different pacing strategies (Additive Metered, Additive Rhythmic, Cued Metered, and Cued Rhythmic). Effects of rate control on sentence and phoneme intelligibility and speech naturalness were examined. Sentence intelligibility improved for both groups, with metered pacing conditions associated with the largest improvement in scores. Similar improvements as speaking rates were reduced were not seen for the phoneme intelligibility task; however, one must recognize that sentence and phoneme intelligibility tasks are different. Slowing the rate of dysarthric speakers did not have as marked an impact on speech naturalness as it did for normal speakers whose naturalness decreased at slowed rates. Metered rate control strategies were associated with the lowest ratings of naturalness for all subject groups. A potential explanation for the discrepancies between the findings for sentence and phoneme intelligibility is offered.

Adult↗

PubMed1989

Perceived articulatory adequacy and velopharyngeal function in dysarthric speakers.

Twenty-four dysarthric speakers with etiologies of brain injury or stroke were placed into one of two groups based on aerodynamic measures of velopharyngeal status. Group I contained 13 individuals who were velopharyngeally incompetent in that nasal air flow was always noted during the stop phase of voiceless plosive sounds. Group II contained 11 individuals who at times achieved complete velopharyngeal closure. Certain measures of perceived articulatory adequacy were found to distinguish between the two groups. Specifically, speakers who were velopharyngeally incompetent produced an articulatory error pattern characterized by better performance for the consonant subcategory nasals-glides than for pressure consonants. Speakers who at times were achieving velopharyngeal closure did not exhibit a marked difference between these two consonant subcategories. Clinical use of measurement of articulatory adequacy as a gross indicator of velopharyngeal competence is suggested and limitations are discussed.

Adolescent↗

PubMed1988

Articulatory adequacy in dysarthric speakers: a comparison of judging formats.

An articulatory inventory was administered to 19 dysarthric adults and scored using two judging formats--phoneme identification and traditional testing. Results indicated that samples judged using the traditional testing format, in which the judge knew the target phoneme, were consistently scored more accurately than those that had been judged using a phoneme identification format, in which the target was not known. Although overall both judging formats were characterized by high inter-rater reliability, the traditional testing format was less reliable than phoneme identification with samples obtained from severely involved speakers. Potential uses of articulatory inventories for dysarthric adults are described.

Adolescent↗

PubMed1987

Speech-muscle visuomotor tracking in dysarthric and nonimpaired speakers.

Assessment of speech-muscle function during nonspeech tasks may provide an important component in the clinical evaluation of speech-motor disorders. Various methodological problems have limited the value of such data in the past. The goal of the present study was to evaluate a set of instrumental, objective procedures for assessment of the nonspeech performance capabilities of different speech-muscle systems. Subjects included 10 nonimpaired adults and a diverse group of 6 adult dysarthric individuals. Each subject performed visuomotor tracking of a 0.6-Hz sinusoidal target with the lower lip, jaw, larynx, and respiratory systems. Cross correlation and phase data were used to describe tracking performance. The nonimpaired subjects showed consistently high cross correlations with little phase shift. The dysarthric subjects showed a wide range of tracking performance which was generally consistent with their overall levels of speech performance and levels of neurological impairment. Differential levels of performance were noted across speech subsystems in some dysarthric subjects. In general, the results suggest that visuomotor-tracking paradigms provide a viable approach to clinical evaluation of speech-muscle function in nonspeech tasks.

Adult↗

PubMed1986

Modification of breath patterning to increase naturalness of a mildly dysarthric speaker.

The case of a 20-year-old, closed head injured male with mild dysarthria is presented. The decreased naturalness of speech was related to short, uniform breath groups, inhalation during every pause, and restricted fundamental frequency. Data related to patterns of breathing and pausing during samples of connected speech along with measures of respiratory control are presented in order to illustrate techniques for assessing and training speech naturalness.

Adult↗

PubMed1985

Communication augmentation systems: quantification in natural settings.

Although observation in clinical settings of communication augmentation system use by severely physically handicapped nonspeaking persons is important, monitoring of such use in natural settings can yield valuable information about the system, communication frequency, and unique communication needs of the individual. This study was designed to evaluate the use of communication partners as data recorders. For nonspeaking, severely physically handicapped subjects were observed in the home, school or treatment settings by a trained observer and a minimally trained communication partner. Issues of partner training and length of time required to obtain a representative sample of communication arose as a result of this study. More work in the areas of automated data collection systems or use of communication partners as data collectors is required before claiming that accurate communication interactions can be recorded in natural settings.

Adolescent↗

PubMed1984

Frequency of word occurrence in communication samples produced by adult communication aid users.

Communication samples generated by five nonspeaking adults using Canon Communicators were collected for 14 consecutive days. Samples were analyzed to determine frequency of word occurrence. A core vocabulary of the 500 most frequently occurring words was analyzed further to determine spelling level and proportion of complete communication samples represented by subsets of the core vocabulary list. The 500 core vocabulary words represented 80% of the total words in the combined communication samples for the 5 subjects. Of all messages generated by the subjects, 33% could be communicated in their entirety using words from the core vocabulary list. The communication of the remaining messages required one or more words in addition to the core vocabulary. The spelling grade level of the words in the core vocabulary list did not exceed the seventh grade. The implications of the results for designing and customizing communication aids and for potential user training are discussed.

Adolescent↗

PubMed1981

Communication efficiency of dysarthric speakers as measured by sentence intelligibility and speaking rate.

In an effort to quantify communication efficiency, speaking rates and intelligibility scores were obtained from a normal speaking adult and 13 dysarthric speakers representing a wide range of severity. Speakers were audio recorded as they read words and sentences. A panel of judges transcribed all recordings and subjectively ranked a randomly selected sample from each speaker according to "communication efficiency." The following measures were obtained for each speaker: word and sentence intelligibility, speaking rate, rates of intelligible and unintelligible speech and a numerical ranking of communication efficiency. Results indicated that speaking rate and speech intelligibility are not closely correlated. By plotting measures that incorporate intelligibility and rate, one can rank speakers similarly to subjective rankings of communication efficiency, and distinguish mildly dysarthric from normal speakers. The addition of intelligibility and rate measures to supplement other assessment procedures in the evaluation of dysarthric speakers is discussed.

Adult↗

PubMed1981

Canon communicator use by adults: a retrospective study.

The purpose of this study was to document aspects of successful Canon Communicator use by 13 subjects. Questionnaires were completed by the speech-language pathologists serving these individuals. Subjects ranged in age from 17 to 64 years. They had used the Canon as a communication augmentation device from 2 to 24 months. All were either anarthric or severely dysarthric as a result of a neurological disorder (cerebral palsy, bilateral CVA, closed head injury, ALS) but none were diagnosed as aphasic. The decision to recommend the Canon was made mre rapidly for older adults. Although a majority of the subjects used more than one communication system, all subjects for whom the Canon remained appropriate (11 of 13) continued to use this device more frequently than other systems. No malfunction other than power supply system was reported.

Adolescent↗

PubMed1981

Ataxic dysarthria: treatment sequences based on intelligibility and prosodic considerations.

Treatment programs of four improving ataxic dysarthric speakers are reviewed. Treatment sequences were based on two overall measures of speech performance-intelligibility and prosody. Increases in intelligibility were initially achieved by control of speaking rate. A hierarchy of rate control strategies, ranging from a rigid imposition of rate through thythmic cueing to self-monitored rate control is discussed. As speakers improved their monitoring skills, a compromise was made between intelligibility and rate. Normal prosodic patterns were not achieved by the ataxic speakers due to difficulty in precisely coordinating the subtle fundamental frequency, loudness and timing adjustments needed to signal stress. Three of the four subjects were taught to use only durational adjustments to signal stress. In this way, they were able to achieve stress on targeted words consistently and minimize bizarreness which resulted from sweeping changes in fundamental frequency and bursts of loudness. The need for further clinically oriented research is discussed.

Adult↗

PubMed1980

A clinician-judged technique for quantifying dysarthric speech based on single-word intelligibility.

A clinician-judged technique for quantifying dysarthric speech based on single-word intelligibility was developed and evaluated in three experiments. Dysarthric speakers were audio-recorded as they read 50-word lists that had been randomly generated from sets of similar sounding words. These tapes were judged by speech pathologists using listening formats that were systematically altered by varying the number of choices available to the judges. Results indicated that some formats were more sensitive to differences that exist among severely dysarthric speakers and others were more sensitive to differences that exist among mild to moderately dysarthric speakers. Judge familiarity with the master word pool increased scores slightly but in a consistent and predictable fashion. Scores from different randomly generated word lists were similar when the influence of a speaker's day-to-day variability was controlled. Clinical implications and uses of this technique for the monitoring of change in speaker performance were discussed.

Adolescent↗

PubMed1980

Influence of passage familiarity on intelligibility estimates of dysarthric speech.

Speech pathologists often estimate intelligibility as dysarthric speakers read standard passages. The first phase of this study compared estimates of intelligibility made by speech pathologists with transcription scores made by judges unfamiliar with the speech passages. Results indicated that speech pathologists consistently overestimated intelligibility. It was hypothesized that judge familiarity with the speech sample contributed to these inflated scores. Therefore, during the second phase of the study the influence of speech sample familiarity on estimates of intelligiblity was investigated. Group of listeners judged mild, moderate, and severely dysarthric speakers under three conditions of familiarity--Unfamiliar (passage unknown), Partially Familiar (passage read twice by a normal speaker), and Most Familiar (script of the passage available). For mild and severely dysarthric speakers, passage familiarity did not significantly influence judges' estimates. For the moderately dysarthric speaker, estimates of intelligibility increased markedly with increasing passage familiarity. Clinical implications of these results are discussed.

Dysarthria↗

PubMed1980

An analysis of connected speech samples of aphasic and normal speakers.

The purpose of this study was to develop a technique for quantifying connected speech samples of aphasic individuals as they recover from the moderate to the mild range of severity. Verbal picture descriptions elicited from mild and moderate aphasic speakers were audio-recorded and compared to those elicited from normal adult and geriatric speakers. These samples were compared on the basis of a measure of amount of information conveyed (content units) and two measures of efficiency including speaking rate (syllables per minute) and rate at which information was conveyed (content units per minute). Results indicated an inverse relationship between severity of aphasia and amount of information conveyed. However, mild and high-moderate aphasic speakers tended to communicate as much information as normal speakers. Both measures of efficiency differentiated groups of mild and high-moderate aphasics from normal speakers as well as differentiating low-moderate from mild aphasic speakers. Use of this quantification system which takes into account both amount of information and efficency of communication is illustrated with data obtained from a recovering aphasic speaker.

Adult↗

PubMed1980

Nonvocal communication: performance evaluation.

With the increasing number of communication options available to severely dysarthric individuals, there is a growing need to develop techniques for the evaluation of nonvocal communication performance. A data collection and analysis system was developed in order to assess the performance of 2 nonvocal communicators. Records of entire messages were obtained along with durational measures of communication partner receiving time for each message, identity of the communication partner and location.

Adult↗