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AMYOTROPHIC LATERAL SCLEROSIS (ALS).
Term Paper ID:29531
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Essay Subject:
Scientific description of the progressive neuromuscular disease.... More...
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Paper Abstract:
Scientific description of the progressive neuromuscular disease. Characterized by a central pathology of degeneration of spinal cord and brainstem, and damage to higher motor centers. Discusses acoustics and speech perception in ALS. Concludes ASL speakers vary significantly in terms of intelligibility and other speech fundamentals.
Paper Introduction:
Research Review: Acoustics and Speech perceptions in ALS
Introduction and Statement of Purpose
Amyotrophic Lateral Sclerosis (ALS) is a progressive neuromuscular disease involving the bulbar musculature at onset in about 25 percent of all cases (Riddel & McCauley, 1995). ALS is characterized by a central pathology of a degeneration of motoneurons of the spinal cord and brainstem and damage to higher motor centers (Kent, Kent, Rosenbek, Weismer, Martin, Sufit, & Brooks, 1992). There is observed variation of lower motor neuron signs (weakness, fasciculations, and atrophy) and upper motor neuron signs (cramps, hyperreflexia, spasticity) across and within individuals with the condition.
Intelligibility of speech productions by patients with ALS can vary significantly (Kent, et al, 1992). Both dysarthria and dysp
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The authors concluded that there is a need forfrequent evaluation of dysarthric ALS patients to better assess therelationship between intelligibility and the acoustic parameters of speech. There was, however, a tendency for the difference invowel space are for content and function words to be smaller for speakerswith ALS than for controls. Weismer, et al (2 ) concluded that the lack of an effect ofincreased rate on the perception of the speech deficit among speakers withALS argues against the notion that the habitually slow rates are a form ofcompensation used to reduce the complexity of speech production. Acoustic differences between content and function words in amyotrophic lateral sclerosis. The magnitude of spectral differences forvowels in content and function words was seen as a better predictor ofimpaired speech than the magnitude of spectral differences for vowels incontent and function words. The finding that local segmental cues for disorderedspeakers tended to be broadly consistent with their overall and slowarticulatory rate suggests that duration does not seem to contribute in asignificant way to intelligibility deficits manifested by persons with ALS. (1994). The acoustic variables studied included total utterance durations,segment durations, estimates of the acoustic vowel space, and slopes offormant transitions. Journal of Speech and Hearing Research, 38 (2), 3 4-315.Silbergleit, A.K., Johnson, A.F., & Jacobson, B.H. Intelligibility and phonetic contrast errors in highly intelligent speakers with ALS. A., Buder, E. They then compared these coefficients to hand-derived spectralmeasures for a subset of speakers. (2 ). Acoustic analysis of dysarthria profile in ALS patients. Each patient saw a neurologist every 1 to 12 weeks and clinicalperformance was assessed using the Norris scale. Such characteristics are associated with ALS, in which mixedneurologic signs are present and in which speech production anomalies ordifficulties can vary significantly from patient to patient. In bothgroups, the mean sound distance between chosen sounds was compared to abasic pattern and was measured on a time-frequency computer acousticanalysis program. C., Weismer, G., Martin, R., Sufit, R., & Brooks, B. Both dysarthria and dysphagia occurfrequently in persons with ALS, complicating vocal production andintelligibility. Research Review: Acoustics and Speech perceptions in ALSIntroduction and Statement of Purpose Amyotrophic Lateral Sclerosis (ALS) is a progressive neuromusculardisease involving the bulbar musculature at onset in about 25 percent ofall cases (Riddel & McCauley, 1995). (2 1). All of the subjects had initial bulbar signs andprogressive phonatory deterioration. (2 1). Noting that dysarthria is a leading disability in ALS patients withmotor neuron degeneration in the bulbar region, Tomik, Krupinski, Glodzik-Sobanska, Bala-Slodowska, Wszolek, Kusiak, and Lechwacka (1999) reportedthat no test was available to detect and follow the progression ofdysarthria. The results reported by Bunton and Weismer (2 1) indicated that thehigh-low vowel contrast was consistent as an error across clinical groups;acoustic characteristics of tongue-height errors were not clearlydifferentiated from the acoustic characteristics of targets. Weismer, et al (2 1)stated that the relation of acoustic measures to scaled speechintelligibility is complex. Folia Phoniatr Logop, 53(1), 1-18.Weismer, G., Laures, J.S., Jeng, J.Y., Kent, R.D., & Kent, J.F. This was interpreted as a reflection of the lossof lingual motoneurons. Turner and Tjaden (2 ) used data generated by the previous studyand an expanded research design to investigate the manner and extent towhich speakers with mild to moderate dysarthria associated with ALS and amatched sample of non-impaired speakers acoustically distinguished /i/,/ae/, /u/, and /a/ in content and function words. ALS patients presented greater compression of the acousticvowel space with increased speaking rate. Subjects spoke at three differentrates and researchers calculated speaking rate, articulation rate, andpause duration and frequency. Neurol Neurochir Pol, 34(5), 865-876.Turner, G.S., & Tjaden, K. The most significantly affected vowels in the bulbar groupwere "b," "o," t, "w," and "t." In the limb group, the most significantlyaffected vowels were "b," t, "t," "w," and "o." The study suggested thatthe progression of ALS can be monitored based on the acoustic analysis of alimited number of sounds and that abnormalities in the dysarthria profilemay appear before any clinical symptoms of the disease are observed. ALS is characterized by a centralpathology of a degeneration of motoneurons of the spinal cord and brainstemand damage to higher motor centers (Kent, Kent, Rosenbek, Weismer, Martin,Sufit, & Brooks, 1992). The perceptual variables included scaled speechintelligibility and severity of speech involvement. F., Kent, R. Context was found to influence the first moment ina similar manner for ALS and non-impaired speakers. Weismer, Jeng, Laures, Kent, and Kent (2 1) examined this issuefurther, comparing a control group of speakers to speakers with ALS orParkinson's disease. Segmental timing in amyotrophic lateral sclerosis. There is observed variation of lower motor neuronsigns (weakness, fasciculations, and atrophy) and upper motor neuron signs(cramps, hyperreflexia, spasticity) across and within individuals with thecondition. Tomik, et al(2 ) therefore suggested that it is possible to detect and measuredysarthria in ALS patients based on acoustic speech analysis. Results showed that participants in both groups were able to increasetheir speaking rate when asked to do so, but that participants with ALSwere significantly slower than the neurologically normal participants atboth rates. Spectral properties of fricatives in amyotrophic lateral sclerosis. (1992). A sample of 47 definite or probable ALS patients and 3 age and sex matched healthy control subjects was developed. Kent, et al (1992) used acoustic signature analysis based ontrajectories of the first and second formants in selected monosyllabic testwords to determine that the mean slope of the second formant was reduced byALS patients when their productions were compared with that of a normalgeriatric control group. The researchers also studied temporal differences for pairsof sound classes and prepausal lengthening of vowels. A similar study by Tomik, Wszolek, Lechwacka, Glodzik-Sobanska, Gryz,and Szczudlik (2 ) assessed dysarthria in ALS subjects using acousticalspeech analysis. (1999). The study wassignificant in that it demonstrated that articulation error rates for malesand females tends to vary across features. Intelligibility of speech productions by patients with ALS can varysignificantly (Kent, et al, 1992). Acoustic analysis of voice in individuals with amyotrophic lateral sclerosis and perceptually normal Voice quality. Results showed decreased performance in dysarthricpatients as compared to non-dysarthric patients at baseline. (1995). D., Rosenbek, J. Measurements of vowel durations and F1 and F2 midpoint frequenciesand vowel space were taken. Results of their tests revealed statistically significant differencesbetween the two groups on measures related to frequency range and phonatorystability. ReferencesBunton, K., & Weismer, G. Results demonstrated the existence of a specific dysarthria profile inALS patients. (1997). Many of the studies of acoustic and perceptual affects of speakingrate adjustments in persons with ALS compare this population toneurologically normal individuals. The influence of speaking rate on vowel space and speech intelligibility for individuals with amyotrophic lateral sclerosis. The results of this somewhat limited case analysis indicated that thephonatory characteristics of women with ALS are not uniform and not onlycan, but do tend to vary significantly from patient to patient. The relationship between perception and acoustics for a high-low vowel contrast produced by speakers with dysarthria. K., Badger, G. Journal of Speech and Hearing Research, 37(3), 496-5 3.Riddel, J., & McCauley, R. (1997). Using a matched sample of ALS and non-impaired subjects, Turner,Tjaden, and Weismer (1995) examined the influence of speaking rate on vowelspace and speech intelligibility. R. Characteristics of speaking rate in the dysarthria associated with amyotrophic lateral sclerosis. O. Intelligibility estimates at each speaking rate were obtained for thedysarthric speakers who exhibited smaller vowel space areas and lesssystematic changes in vowel space as a function of speaking rate than didneurologically intact subjects. A further goal of thestudy was to evaluate the relationship between impaired speech in ALS andthe magnitude of acoustic differences for vowels in content and functionwords. Using a sample of 9 subjects with ALS and 9 age-matched and gender-matched neurologically intact controls, Turner and Weismer (1993) examinedthe ability to alter speaking rate. Finally, they found thattemporal differences for sound classes (including voiceless-voicedfricatives, long-short vowels, and prepausal lengthening for speakers withALS were typically similar to healthy speakers' habitual and slow speech.There was substantial variability observed within both speaker groups andreversals of expected effects; the implication of this variability is thattemporal differences for sound classes, such as short and long vowels, arenot a reliable perceptual cue for listeners. A study by Strand, Buder, Yorkston, and Ramig (1994) moved from theassertion that patients exhibiting specific neural subsystem involvementare often reported as presenting with particular perceptual characteristicsof voice. Weismer, Laures, Jeng, Kent, and Kent(2 ) explored this issue using sentence utterances from both groups ofpatients at the habitual and fast speaking rates. Significantly, F2 transition rates of less than 4 Hz/msec were seenonly in dysarthric ALS patients. Journal of Voice, 11(2), 223-231.Strand, E. Tjaden and Turner (1997) examined whether spectra for ALS and healthyspeakers were influenced similarly by context. Tomik, et al (2 ) further found that these abnormalities weresignificantly increased in the dysarthric ALS subjects. Results also suggested that vowelspaces were smaller for both neurogenic groups than for the controls, butsignificantly so only for the ALS speakers. Journal of Speech, Language & Hearing Research, 44(6), 1215-1229.Kent, J. The most significant resultgenerated by the study was the finding that there are gender-relateddifferences manifested in speech production by ALS patients. (2 ). Intelligibility and the acoustic characteristics of speech in amyotrophic lateral sclerosis. Strand, et al(1994) reported acoustic data on the phonatory performance of four womendiagnosed with ALS. Differential phonatory characteristics of four women with amyotrophic lateral sclerosis. Acoustic measures andmagnitude estimates of speech intelligibility and the severity speechinvolvement were taken. (1994). Tjaden and Turner (2 ) also commented, based on this study, thatthe slowed rate of ALS is not uniformly distributed across phonetic eventsbut does influence segment durations of particular sound categoriesconsistent in ways that are consistent with the disease process. (1995). Effect of speaking rate manipulations on acoustic and perceptual aspects of the dysarthria in amyographic lateral sclerosis. The results of the ALS-Control habitual speech comparison suggestedthat the slowed articulatory rate of ALS influences segmental timing formost phonetic events. Silbergleit, Johnson, and Jacobson (1997) hypothesized that objectiveanalysis of voice would reveal significant differences on specific acousticparameters of voice when ALS subjects were compared to a control group.These researchers stated that early phonatory changes occurring in ALS werenot at the time of their study well understood. This study was designed to explore the relationshipbetween perception of high-low vowel content and its acoustic correlates intoken speech produced by persons with motor speech impairments. Journal of Speech, Language & Hearing Research, 43(3), 683-696.Tomik, B., Krupinski, J., Glodzik-Sobanska, L., Bala- Slodowska, M., Wszolek, W., Kusiak, M., & Lechwacka, A. Evaluation of dysarthria with the assistance of acoustic speech analysis in patients with amyotrophic lateral sclerosis. Journal of Speech, Language & Research, 43(3), 769-782.Turner, G.S., Tjaden, K., & Weismer, G. Quantitative description of the dysarthria in women with amyotrophic lateral sclerosis. Measurements were taken of single word intelligibility,F2 formant trajectories (including extent, duration, and rate), anddiadochokinetic rate. A computer-based acousticmethod evaluating dysarthria was employed three times for each subject. A comparison study of two different groups of ALS patients (7 whowere dysarthric and 7 who were non-dysarthric) was conducted over a six-month period by Mulligan, Carpenter, Riddel, Delaney, Badger, Krusinski,and Tandan (1994). Riddel and McCauley (1995) examined intelligibility data, phoneticcontrast errors, and information regarding subsystem involvement in asample of 29 highly intelligible ALS patients. Vowel space was found to account for 45percent of the variance in speech intelligibility, suggesting that thisfactor is an important component of global estimates of speechintelligibility. The literature further suggests that tests ofintelligibility and disease effects must be improved to better serve ALSand other neurologically impaired individuals with speech deficits.Developing appropriate therapeutic interventions can only follow thoroughanalysis of the nature and locus of speech impairments specific to ALS. J. Acoustic and intelligibility characteristics of sentence production in neurogenic speech disorders. Journal of Speech & Hearing Research, 36(6), 1134-1145.Weismer, G., Jeng, J.Y., Laures, J.S., Kent, R.D., & Kent, J.F. Journal of Speech & Hearing Research, 35(4), 723-734.Mulligan, M., Carpenter, J., Riddel, J., Delaney, M. They analyzed sentences produced by each groupacoustically and perceptually. Using three different speaking rates,vowel segment durations and target formant frequencies were measured fromselect words containing specific vowels. They looked at first momentcoefficients for three occurrences of /s/ in the word "some" for individualspeakers. Women with ALS also demonstrated abnormalities in fundamentalfrequencies, perturbations of frequency (jitter), amplitude (shimmer), andsignal-to-noise ratio. Perceptual judgments of speaking rate indicated thatdysarthric speakers spoke faster for a given physical speaking rate.Finally, results of the study suggested that the function relating physicalto perceived speaking rate grew more rapidly for dysarthric than for normalspeakers. Recent research on the acoustics of ALS suggests that anumber of factors may account for the observed variances. Journal of Speech, Language & Hearing Research, 4 (6), 1358-1373.Tjaden, K., & Turner, G.S. A clinical interpretation offered by Turnerand Tjaden (2 ) is that individuals presenting with ALS may benefit fromtherapy techniques that target temporal properties of the acoustic signal. H., Yorkston, K. Krusinski, P., & Tandan, R. The perceptual measures used inthe study failed to show any effect of the speaking rate adjustment onscaled intelligibility of severity for either group. It is thepurpose of this report to examine selected items from the professional andscientific literature, focusing on the acoustics and the perception ofspeech in terms of spectral and/or temporal cues and/or suprasegmentaldistinctions in ALS, to determine what constitutes state-of-the-artknowledge regarding the condition and its manifestations.Review of Literature Kent, et al (1992) studied speech intelligibility and its phoneticand acoustic correlates in a sample of 1 women diagnosed with ALS. Journal of Speech & Hearing Research, 38(5), 1 1-1 14.Turner, G.S., & Weismer, G. Journal of Neurological Science, 169(1-2), 35-42.Tomik, B., Wszolek, W., Lechwacka, A., Glodzik-Sobanska, L., Gryz, E.A., & Szczudlik, A. Estimates ofboth intelligibility and severity of impairment for ALS speakers are seenas necessary for meaningful clinical assessments.Summary The research reviewed in this brief report tends to demonstrate thatALS speakers vary significantly against one another and with respect to non-impaired speakers in terms of intelligibility as well as other speechfundamentals. A word-identification test was used to assess intelligibility; results indicatedthat the most disrupted phonetic features pertained to velopharyngealvalving, lingual function for consonant contrasts of place and manner, andsyllable shape. The authors found that the proportionalincrease in speaking rate was similar between the groups, but thedysarthric speakers slowed rate to a smaller extent. There was evidence that dysarthric speakers showed a greaterdependence on pause duration and frequency as compared to articulation ratewhen increasing rate. (2 ). Silbergleit, et al (1997) concluded that it is possible thatearly bulbar signs affecting the laryngeal system may be present in ALSpatients before perceptually aberrant vocal characteristics occur. Anintelligibility test that groups target and error words in minimal-paircontrasts was used - a format that allowed for construction of phoneticerror profiles based on listener responses, thus permitting a directcomparison of the acoustic characteristics of vowels perceived as theintended target with those heard as something other than the target. Journal of Voice, 8(4), 327-339.Tjaden, K., & Turner, G.S. The study was useful in enhancing knowledge regarding the means bywhich dysarthric speakers alter speaking rate and in creating a model thatcan be used to help ALS patients choose a rate manipulation method thattaps into their strengths (Turner & Weismer, 1993). The authors also found that a linear function accounted for asignificant proportion of the variance in the relationship betweenconsonant precision ratings and the frequency difference between the firstmoment for /s/ and /j/. M., & Ramig, L. Overall ranking of errors was similar for males andfemales with ALS, while men were more likely than females to haveimpairments of voicing in syllable-initial position. Earlylaryngeal involvement was also found to directly impact on the number andseverity of changes in phonation, manifested in increased jitter andshimmer. The studywas significant in that it assists clinicians in developing appropriatetests and measures to assess the progress of ALS in both bulbar and limbonset patients. The final study to be discussed herein was conducted by Bunton andWeismer (2 1). Folia Phoinatr Logop, 52(5), 2 1-219. Theoverall pattern of segmental timing for speakers with ALS was similar tothat of slowed speech for non-impaired speakers. (2 ). As Strand,et al (1994) concluded, this has significant implications for therapeuticinterventions, which must be tailored to each patient. The researchers studied 53 patients with definite or probableALS. (1993). Results indicated that all sounds were incorrect in all ALS subjects. Results indicated that the temporalvariables typically differentiated the ALS patients but not the Parkinson'sdisease patients from the controls. A relationship between the F2 transitionrate and single word intelligibility was noted for patients with moderateto high intelligibility. At lower levels of intelligibility, Mulligan, etal (1994) found that the F2 rate reached a plateau in spite of continuedintelligibility declines. Segment durations for ALS speakers' habitual rates werecompared to segment durations for healthy speakers' habitual and slowreading rates. Tjaden and Turner (2 ) described segmental timing patterns for apassage read by speakers with ALS and a matched sample of neurologicallyhealthy speakers. Results reported by these researchers emphasized that the magnitudeof F1, F2, vowel space area and duration differences for vowels in contentand function words was not statistically different from ALS and non-impaired speakers. Results indicated articulatorydifferences in /s/ and /j/ for ALS speakers and healthy controls as indexedby between-group differences in first moment coefficients.
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