Kris Tjaden

Speech and Swallowing in Parkinson's Disease.

Dysarthria and dysphagia occur frequently in Parkinsons disease (PD). Reduced speech intelligibility is a significant functional limitation of dysarthria and in the case of PD is likely related to articulatory and phonatory impairment. Prosodically based treatments prove to be the most promising for addressing these deficits as well as for maximizing speech intelligibility. Communication-oriented strategies may also help enhance mutual understanding between a speaker and a listener. Dysphagia in PD can result in serious health issues, including aspiration pneumonia, malnutrition, and dehydration. Early identification of swallowing abnormalities is critical so as to minimize the impact of dysphagia on health status and quality of life. Feeding modifications, compensatory strategies, and therapeutic swallowing techniques all have a role in the management of dysphagia in PD.

Characteristics of Diadochokinesis in Multiple Sclerosis and Parkinson’s Disease

Diadochokinesis (DDK) for speakers with dysarthria has been described using a variety of acoustic measures. A clinical protocol for the objective assessment of DDK requires a unified approach, however, to facilitate implementation across clinics and laboratories. A protocol for the acoustic analysis of DDK that incorporates temporal and energy measures has been used to describe DDK characteristics for dysarthria secondary to stroke as well as ataxic dysarthria. The current study sought to validate and extend the protocol to a new set of etiological groups, including dysarthria secondary to multiple sclerosis (MS) and Parkinson’s disease (PD). The results suggest that temporal measures are more useful than energy measures for distinguishing among dysarthria secondary to MS, dysarthria secondary to PD, and healthy controls. The results also highlight the value of including both alternating and sequential motion rate tasks in the assessment of DDK and of supplementing quantitative measures with qualitative spectrographic observations.

Impact of clear, loud, and slow speech on scaled intelligibility and speech severity in Parkinson's disease and multiple sclerosis.

PURPOSE The perceptual consequences of rate reduction, increased vocal intensity, and clear speech were studied in speakers with multiple sclerosis (MS), Parkinsons disease (PD), and healthy controls. METHOD Seventy-eight speakers read sentences in habitual, clear, loud, and slow conditions. Sentences were equated for peak amplitude and mixed with multitalker babble for presentation to listeners. Using a computerized visual analog scale, listeners judged intelligibility or speech severity as operationally defined in Sussman and Tjaden (2012). RESULTS Loud and clear but not slow conditions improved intelligibility relative to the habitual condition. With the exception of the loud condition for the PD group, speech severity did not improve above habitual and was reduced relative to habitual in some instances. Intelligibility and speech severity were strongly related, but relationships for disordered speakers were weaker in clear and slow conditions versus habitual. CONCLUSIONS Both clear and loud speech show promise for improving intelligibility and maintaining or improving speech severity in multitalker babble for speakers with mild dysarthria secondary to MS or PD, at least as these perceptual constructs were defined and measured in this study. Although scaled intelligibility and speech severity overlap, the metrics further appear to have some separate value in documenting treatment-related speech changes.

Effects of speaking task on intelligibility in Parkinson's disease.

Intelligibility tests for dysarthria typically provide an estimate of overall severity for speech materials elicited through imitation or read from a printed script. The extent to which these types of tasks and procedures reflect intelligibility for extemporaneous speech is not well understood. The purpose of this study was to compare intelligibility estimates obtained for a reading passage and an extemporaneous monologue produced by12 speakers with Parkinsons disease (PD). The relationship between structural characteristics of utterances and scaled intelligibility was explored within speakers. Speakers were audio-recorded while reading a paragraph and producing a monologue. Speech samples were separated into individual utterances for presentation to 70 listeners who judged intelligibility using orthographic transcription and direct magnitude estimation (DME). Results suggest that scaled estimates of intelligibility for reading show potential for indexing intelligibility of an extemporaneous monologue. Within-speaker variation in scaled intelligibility also was related to the number of words per speech run for extemporaneous speech.

Intelligibility in dysarthria: Effects of listener familiarity and speaking condition

This study examined the effects of familiarization and speaking condition on sentence intelligibility for a speaker with dysarthria secondary to a traumatic brain injury (TBI). Familiarization procedures included hearing the speaker read a paragraph or a word list comprised of a random ordering of the words in the paragraph. Such an approach allowed for statements concerning the benefit of prior exposure to a sentence‐level prosody and word level articulatory‐acoustic patterns versus only word‐level articulatory‐acoustic patterns. Following word list, paragraph, or no familiarization, listeners orthographically transcribed sentences in either a habitual, slow, fast, or loud condition. Listeners receiving either word list or paragraph familiarization accurately transcribed a higher percentage of words in sentences than listeners receiving no familiarization. Intelligibility scores did not differ for word list or paragraph familiarization, however. Listeners also were more accurate transcribing sentences produced in the loud condition compared to habitual and fast conditions. Clinical implications are discussed.

The Impact of Rate Reduction and Increased Loudness on Fundamental Frequency Characteristics in Dysarthria

Objective: This study examined the extent to which articulatory rate reduction and increased loudness were associated with adjustments in utterance-level measures of fundamental frequency (F₀) variability for speakers with dysarthria and healthy controls that have been shown to impact on intelligibility in previously published studies. More generally, the current study sought to compare and contrast how a slower-than-normal rate and increased vocal loudness impact on a variety of utterance-level F₀ characteristics for speakers with dysarthria and healthy controls. Patients and Methods: Eleven speakers with Parkinson’s disease, 15 speakers with multiple sclerosis, and 14 healthy control speakers were audio recorded while reading a passage in habitual, loud, and slow conditions. Magnitude production was used to elicit variations in rate and loudness. Acoustic measures of duration, intensity and F₀ were obtained. Results and Conclusions: For all speaker groups, a slower-than-normal articulatory rate and increased vocal loudness had distinct effects on F₀ relative to the habitual condition, including a tendency for measures of F₀ variation to be greater in the loud condition and reduced in the slow condition. These results suggest implications for the treatment of dysarthria.

Acoustic and perceptual consequences of clear and loud speech.

Objective: Several issues concerning F2 slope in dysarthria were addressed by obtaining speech acoustic measures and judgments of intelligibility for sentences produced in Habitual, Clear and Loud conditions by speakers with Parkinsons disease (PD) and healthy controls. Patients and Methods: Acoustic measures of average and maximum F2 slope for diphthongs, duration and intensity were obtained. Listeners judged intelligibility using a visual analog scale. Differences in measures among groups and conditions as well as relationships among measures were examined. Results: Average and maximum F2 slope metrics were strongly correlated, but only average F2 slope consistently differed among groups and conditions, with shallower slopes for the PD group and steeper slopes for Clear speech versus Habitual and Loud. Clear and Loud speech were also characterized by lengthened durations, increased intensity and improved intelligibility versus Habitual. F2 slope and intensity were unrelated, and F2 slope was a significant predictor of intelligibility. Conclusion: Average diphthong F2 slope was more sensitive than maximum F2 slope to articulatory mechanism involvement in mild dysarthria in PD. F2 slope holds promise as an objective measure of treatment-related changes in the articulatory mechanism for therapeutic techniques that focus on articulation.

Speech and Pause Characteristics Associated with Voluntary Rate Reduction in Parkinson’s disease and Multiple Sclerosis

UNLABELLED The primary purpose of this study was to investigate how speakers with Parkinsons disease (PD) and Multiple Sclerosis (MS) accomplish voluntary reductions in speech rate. A group of talkers with no history of neurological disease was included for comparison. This study was motivated by the idea that knowledge of how speakers with dysarthria voluntarily accomplish a reduced speech rate would contribute toward a descriptive model of speaking rate change in dysarthria. Such a model has the potential to assist in identifying rate control strategies to receive focus in clinical treatment programs and also would advance understanding of global speech timing in dysarthria. All speakers read a passage in Habitual and Slow conditions. Speech rate, articulation rate, pause duration, and pause frequency were measured. All speaker groups adjusted articulation time as well as pause time to reduce overall speech rate. Group differences in how voluntary rate reduction was accomplished were primarily one of quantity or degree. Overall, a slower-than-normal rate was associated with a reduced articulation rate, shorter speech runs that included fewer syllables, and longer more frequent pauses. Taken together, these results suggest that existing skills or strategies used by patients should be emphasized in dysarthria training programs focusing on rate reduction. Results further suggest that a model of voluntary speech rate reduction based on neurologically normal speech shows promise as being applicable for mild to moderate dysarthria. LEARNING OUTCOMES The reader will be able to: (1) describe the importance of studying voluntary adjustments in speech rate in dysarthria, (2) discuss how speakers with Parkinsons disease and Multiple Sclerosis adjust articulation time and pause time to slow speech rate.

Comparison of Intelligibility Measures for Adults With Parkinson's Disease, Adults With Multiple Sclerosis, and Healthy Controls

PURPOSE This study obtained judgments of sentence intelligibility using orthographic transcription for comparison with previously reported intelligibility judgments obtained using a visual analog scale (VAS) for individuals with Parkinsons disease and multiple sclerosis and healthy controls (K. Tjaden, J. E. Sussman, & G. E. Wilding, 2014). METHOD Speakers read Harvard sentences in habitual, clear, loud, and slow conditions. Sentence stimuli were equated for peak intensity and mixed with multitalker babble. A total of 50 listeners orthographically transcribed sentences. Procedures were identical to those for a VAS reported in Tjaden, Sussman, and Wilding (2014). RESULTS The percent correct scores from transcription were significantly higher in magnitude than the VAS scores. Multivariate linear modeling indicated that the pattern of findings for transcription and VAS was virtually the same with respect to differences among groups and speaking conditions. Correlation analyses further indicated a moderately strong, positive relationship between the two metrics. The majority of these correlations were significant. Last, intrajudge and interjudge listener reliability metrics for the two intelligibility tasks were comparable. CONCLUSION Results suggest that there may be instances when the less time-consuming VAS task may be a viable substitute for an orthographic transcription task when documenting intelligibility in mild dysarthria.

Hybridizing conversational and clear speech to investigate the source of increased intelligibility in speakers with Parkinson's disease.

PURPOSE A speech analysis-resynthesis paradigm was used to investigate segmental and suprasegmental acoustic variables explaining intelligibility variation for 2 speakers with Parkinsons disease (PD). METHOD Sentences were read in conversational and clear styles. Acoustic characteristics from clear sentences were extracted and applied to conversational sentences, yielding 6 hybridized versions of sentences in which segment durations, short-term spectrum, energy characteristics, or fundamental frequency characteristics for clear productions were applied individually or in combination to conversational productions. Listeners (N = 20) judged intelligibility in transcription and scaling tasks. RESULTS Intelligibility increases above conversation were more robust for transcription, but the pattern of intelligibility improvement was similar across tasks. For 1 speaker, hybridization involving only clear energy characteristics yielded an 8.7% improvement in transcription intelligibility above conversation. For the other speaker, hybridization involving clear spectrum yielded an 18% intelligibility improvement, whereas hybridization involving both clear spectrum and duration yielded a 13.4% improvement. CONCLUSIONS Not all production changes accompanying clear speech explain its improved intelligibility. Suprasegmental adjustments contributed to intelligibility improvements when segmental adjustments, as inferred from vowel space area, were not robust. Hybridization can be used to identify acoustic variables explaining intelligibility variation in mild dysarthria secondary to PD.