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Biomedical subjects

G Weismer

Publications and source records attributed to G Weismer.

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

Oral structure nonspeech motor control in normal, dysarthric, aphasic and apraxic speakers: isometric force and static position control.

This study investigated the isometric force and static position control of the upper lip, lower lip, tongue, jaw, and finger in four subject groups (normal control, apraxia of speech, conduction aphasia, and ataxic dysarthria) at two force and displacement levels. Results from both the force and position tasks suggested that the apraxic and dysarthric groups tended to produce significantly greater instability than the normal group, although the pattern of instability across articulators was not systematic within or across the force and position experiments for subjects within or between groups. The conduction aphasic group produced force and position stability that typically was not significantly different from any of the remaining three groups, suggesting that their force and position stability as indexed in the present study fell somewhere between that of the normal group and the apraxic and dysarthric groups. It is suggested that other analyses of force and position control, such as descriptive accounts of the trial-by-trial time histories, might shed additional light on the speech and orofacial sensorimotor control deficits in persons with apraxia, dysarthria, and conduction aphasia.

Adult↗
PubMed1990

Statistical comparison of movement amplitudes from groupings of normal geriatric speakers.

An implicit assumption of many studies of articulatory kinematics is that all normal speakers are equivalent, at least in a statistical sense. The present report investigated this assumption by performing post hoc analyses on random groups of 8 normal, geriatric males. Results of these analyses suggest that, at least for the geriatric population, small numbers of subjects may not represent the parent population adequately, especially when the unit of statistical analysis is the individual trial. These findings have implications for the types of generalizations that can be made from studies with small samples and suggest the need for more comprehensive investigations of speech kinematics.

Aged↗
PubMed1990

Selected acoustic characteristics of speech production in very old males.

An understanding of the effects of advancing age on speech characteristics is crucial for those who study and serve the older population. The purpose of this study was to obtain a normative data base for the speech production characteristics of a group of very old men. Fourteen veterans 87 to 93 years old served as subjects, producing a total of 40 sentences at a conversational rate. Wide-band (300 Hz) spectrograms were created from high-quality tape recordings. Specified acoustic measures were made (consonant, vowel, and voice-onset time durations; and vowel formant frequencies and trajectory slopes) via digitizer and microcomputer Sonogram Analyzer program. Descriptive analysis of the selected measurements was performed to obtain a profile of speech production behavior for these subjects. Data were also compared to those of the young adult, Parkinson's disease patients, and younger elderly subjects studied by Weismer (1984a) and Weismer, Kimelman, and Gorman (1985). Performance of the older subjects was similar to that of the younger elderly in many cases, but in certain cases bore notable similarities to Parkinsonian speech. Theoretical implications of aging and disease are addressed.

Aged↗
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↗
PubMed1989

Kinematic, acoustic, and perceptual analyses of connected speech produced by parkinsonian and normal geriatric adults.

Acoustic and kinematic analyses, as well as perceptual evaluation, were conducted on the speech of Parkinsonian and normal geriatric adults. As a group, the Parkinsonian speakers had very limited jaw movement compared to the normal geriatrics. For opening gestures, jaw displacements and velocities produced by the Parkinsonian subjects were about half those produced by the normal geriatrics. Lower lip movement amplitude and velocity also were reduced for the Parkinsonian speakers relative to the normal geriatrics, but the magnitude of the reduction was not as great as that seen in the jaw. Lower lip closing velocities expressed as a function of movement amplitude were greater for the Parkinsonian speakers than for the normal geriatrics. This increased velocity of lower lip movement may reflect a difference in the control of lip elevation for the Parkinsonian speakers, an effect that increased with the severity of dysarthria. Acoustically, the Parkinsonian subjects had reduced durations of vocalic segments, reduced formant transitions, and increased voice onset time compared to the normal geriatrics. These effects were greater for the more severe, compared to the milder, dysarthrics and were most apparent in the more complex, vocalic gestures.

Acoustic Stimulation↗
PubMed1988

The effects of three feedback modes on the ability of normal geriatric individuals to match speaking rate.

The present study investigated the effects of three feedback modes (visual-verbal, verbal-quantitative, and verbal-qualitative) on the ability of 30 normal geriatric individuals to match three different speaking rates (slow, average, and fast). Ten subjects were randomly assigned to each feedback condition. Each subject was instructed to produce the stimulus phrase, Buy Bobby a doughnut, at each of the three speaking rates. Subjects in the visual-verbal mode received both visual feedback of the utterance duration via a PM Trainer and verbal feedback from the experimenter indicating the subject's accuracy in matching the specified speaking rate. Feedback during the verbal-quantitative condition consisted of verbal information indicating the subject's accuracy in matching each speaking rate. The verbal-qualitative condition consisted of verbal feedback relative to the subject's ability to match speaking rate, although the feedback was less precise than in the other conditions. Results suggest that visual-verbal and verbal-quantitative feedback lead to significantly better performance than verbal-qualitative feedback in matching speaking rate, particularly when the task becomes more difficult. These results have implications for the training of a similar task in speech-disordered populations.

Aged↗
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↗
PubMed1988

Statistical analysis of word-initial voiceless obstruents: preliminary data.

A statistical procedure for classifying word-initial voiceless obstruents is described. The data set to which the analysis was applied consisted of monosyllabic words starting with a voiceless obstruent. Each word was repeated six times in the carrier phrase "I can say again" by each of ten speakers. Fast Fourier transforms (FFTs), using a 20-ms Hamming window, were calculated every 10 ms from the onset of the obstruent through the third cycle of the following vowel. Each FFT was treated as a random probability distribution from which the first four moments (mean, variance, skewness, and kurtosis) were computed. Moments were calculated from linear and Bark transformed spectra. Data were pooled across vowel contexts for speakers of a given gender and input to a discriminant analysis. Using the moments calculated from the linear spectra, 92% of the voiceless stops were classified correctly when dynamic aspects of the stop were included. Even more important, the model constructed from the males' data correctly classified about 94% of the voiceless stops produced by the female speakers. Classification of the voiceless fricatives when all places of articulation were included in the analysis did not exceed 80% correct when the moments from either the linear or Bark transformed scales were used. However, classification of only the voiceless sibilants was 98% correct when the moments from the Bark transformed spectra were used. As with the stops, the classification model held across gender.

Adolescent↗
PubMed1985

Constancy of (acoustic) relative timing measures in phrase-level utterances.

The hypothesis that acoustic measures of relative speech timing remain constant across large changes in speaking rate was tested for fluent utterances produced by normal and neurogenically disordered speakers. For all speakers, relative timing tended to be statistically invariable across conversational and fast speaking rates. This finding was considered especially interesting in the case of speakers with dysarthria and apraxia of speech, because absolute measures of speech timing associated with these disorders are typically aberrant. A post hoc analysis of relative variability across speakers showed the ratio measures to be consistently less variable than measures of absolute interval duration. The greater similarity across speakers of ratio measures, as compared to interval measures, was taken to mean that characterizing the temporal structure of articulatory sequences in terms of relative timing is an appropriate way to capture an important aspect of the biological constraints associated with speech production.

Adult↗
PubMed1982

Temporal characteristics of "functionally" misarticulated /s/ in 4- to 6-year-old children.

This paper reviews instrumental studies of "functional" misarticulations in children and reports an experiment involving acoustic measures of the duration of normally articulated and misarticulated /s/. Three subject groups (n = 7 in each group) included normally articulating adults, normally articulating children, and children who misarticulate the /s/ sound. Multiple repetitions of nonsense sequences containing /s/ were obtained from each subject, and group and individual subject comparisons were based on means, standard deviations, and the derived coefficient of variation associated with /s/ duration. Results indicate that /s/ durations of misarticulating children are significantly more variable than those of normally articulating children, and that this difference is more striking in /s/-stop clusters than in the case of singleton /s/. The possibility is raised that the variability differences between the two child groups may reflect differences in speech motor control capabilities. It is suggested that such control differences should predict temporal variability differences between the two child groups for sounds which are articulated correctly by children in both groups. In addition, these variability differences should be observed for the spectral dimension of speech sound production, since this measure is sensitive to control of articulatory configuration.

Adult↗
PubMed1981

A study of the voicing distinction associated with omitted, work-final stops.

This study examined the possibility that children who omit word-final stops as a clinical entity may preserve the voicing contrast of those omitted stops by differential durations of the receding vowel. Data bearing on this hypothesis were obtained by constructing a speech sample in which the voicing of word-final stops was systematically manipulated and by having three children produce these utterances under controlled conditions. Acoustic measures of vowel durations showed that for all word-final stops in both isolated words and words in sentence-final position that were judged unanimously by three transcribers to be omitted, two of the children produced vowel durations that were clearly sensitive to the voicing characteristic of the (omitted) final stop. The third child failed to show a consistent difference in vowel duration dependent on the voicing of the final stop. A phonological analysis of spontaneous speech sample showed that the two children who produced the reliable vowel duration difference also showed clear phonetic evidence of medial stops when the form containing the omitted final stop was inflected. The third child, however, omitted stops in both inflected and noninflected forms. These results are discussed in terms of the conditions that may be necessary for a child to use differential vowel durations to mark the voicing of omitted, work-final stops.

Articulation Disorders↗
PubMed1980

Segmental gestures at the laryngeal level in whispered speech: evidence from an aerodynamic study.

Peak intraoral air pressure and flow were measured simultaneously for the syllables /pa/ and /ba/ in two speaking conditions (syllable repetitions, and in carrier phrases) and in two phonation modes (normal phonation and whisper). Results indicated that 1) the difference between the intraoral air pressure for /p/ and /b/ was statistically significant in normal phonation, but not in whisper, 2) the difference in peak flow for /p/ and /b/ was statistically significant in both normal phonation and whisper, and 3) the pressure and flow data were unaffected by speaking conditions. These data, plus a subsequent analysis of intraoral pressure slopes, are taken to indicate that the voiceless and voiced members of a stop-cognate pair are produced in whisper with unique laryngeal gestures.

Adult↗
PubMed1979

Phrase-level timing patterns in English: effects of emphatic stress location and speaking rate.

Phrase-level timing patterns in the utterance Bob hit the big dog were studied as a function of emphatic-stress location at two speaking rates. Five emphatic-stress conditions were defined: emphasis on each of the four content words, and one condition with no emphatic stress (neutral emphasis). Three subjects produced twenty repetitions of each condition at both rates. Results showed (1) the effect of emphatic stress on segment duration was not confined to the emphasized segments, but was manifest in nonemphasized segments as well; (2) when emphatic stress occurred near the beginning of the utterance, segment durations toward the end of the utterance were shortened relative to the duration of these segments in the neutral-emphasis utterance; however, for emphatic stress late in the utterance, beginning segments were not so modified; (3) the duration correlate of emphasis varied with position-in-utterance; and (4) increased speaking rate reduced or eliminated timing contrasts observed at the conversational rate, and affected the utterance-final segment differently from segments in other utterance positions.

Adult↗