A Cognitive-Perceptual Approach to Conceptualizing Speech Intelligibility Deficits and Remediation Practice in Hypokinetic Dysarthria

Hypokinetic dysarthria is a common manifestation of Parkinson's disease, which negatively influences quality of life. Behavioral techniques that aim to improve speech intelligibility constitute the bulk of intervention strategies for this population, as the dysarthria does not often respond vigorously to medical interventions. Although several case and group studies generally support the efficacy of behavioral treatment, much work remains to establish a rigorous evidence base. This absence of definitive research leaves both the speech-language pathologist and referring physician with the task of determining the feasibility and nature of therapy for intelligibility remediation in PD. The purpose of this paper is to introduce a novel framework for medical practitioners in which to conceptualize and justify potential targets for speech remediation. The most commonly targeted deficits (e.g., speaking rate and vocal loudness) can be supported by this approach, as well as underutilized and novel treatment targets that aim at the listener's perceptual skills

Data, Output, and Code: A Clinical Advantage: Experience informs recognition and adaptation to a novel talker with dysarthria

Perceptual training paradigms, which leverage the mechanism of perceptual learning, show that naïve listeners, those with no prior experience with dysarthria, benefit from explicit familiarization with a talker with dysarthria. The assumption, that familiarization affords listeners an opportunity to acquire distributional knowledge of the degraded speech signal. Here, we extend investigations to clinically experienced listeners, Speech-Language Pathologists (SLPs), and advance models of listener recognition and adaptation to dysarthric speech

Generalized Adaptation to Dysarthric Speech

Purpose Generalization of perceptual learning has received limited attention in listener adaptation studies with dysarthric speech. This study investigated whether adaptation to a talker with dysarthria could be predicted by the nature of the listener\u27s prior familiarization experience, specifically similarity of perceptual features, and level of intelligibility. Method Following an intelligibility pretest involving a talker with ataxic dysarthria, 160 listeners were familiarized with 1 of 7 talkers with dysarthria—who differed from the test talker in terms of perceptual similarity (same, similar, dissimilar) and level of intelligibility (low, mid, high)—or a talker with no neurological impairment (control). Listeners then completed an intelligibility posttest on the test talker. Results All listeners benefited from familiarization with a talker with dysarthria; however, adaptation to the test talker was superior when the familiarization talker had similar perceptual features and reduced when the familiarization talker had low intelligibility. Conclusion Evidence for both generalization and specificity of learning highlights the differential value of listeners\u27 prior experiences for adaptation to, and improved understanding of, a talker with dysarthria. These findings broaden our theoretical knowledge of adaptation to degraded speech, as well as the clinical application of training paradigms that exploit perceptual processes for therapeutic gain

Understanding Dysrhythmic Speech: When Rhythm Does Not Matter and Learning Does Not Happen

A positive relationship between rhythm perception and improved understanding of a naturally dysrhythmic speech signal, ataxic dysarthria, has been previously reported [Borrie, Lansford, and Barrett. (2017). J. Speech Lang. Hear. Res. 60, 3110–3117]. The current follow-on investigation suggests that this relationship depends on the nature of the dysrhythmia. When the corrupted rhythm cues are relatively predictable, affording some learnable acoustic regularity, the relationship is replicated. However, this relationship is nonexistent, along with any intelligibility improvements, when the corrupted rhythm cues are unpredictable. Findings highlight a key role for rhythm perception and distributional regularities in adaptation to dysrhythmic speech

Cognitive predictors of perception and adaptation to dysarthric speech: Preprint, Data, Code, and Output

Although recruitment of cognitive-linguistic resources to support dysarthric speech perception and adaptation is presumed by theoretical accounts of effortful listening and supported by cross-disciplinary empirical findings, prospective relationships have received limited attention in the disordered speech literature. The current study aimed to examine the predictive relationships between cognitive-linguistic parameters and intelligibility outcomes associated with familiarization with dysarthric speech in young adult listeners. A cohort of 156 listener participants between the ages of 18 and 50 years completed a three-phase perceptual training protocol (pretest, training, posttest) with one of three speakers with dysarthria. Additionally, listeners completed the NIH Toolbox Cognition Battery to obtain measures of the following cognitive-linguistic constructs: working memory, inhibitory control of attention, cognitive flexibility, processing speed, and vocabulary knowledge. Elastic net regression models revealed select cognitive-linguistic measures and their two-way interactions predicted both initial intelligibility and intelligibility improvement of dysarthric speech. While some consistency across models was shown, unique constellations of select cognitive factors and their interactions predicted initial intelligibility and intelligibility improvement of the three different speakers with dysarthria. Current findings extend empirical support for theoretical models of speech perception in adverse listening conditions to dysarthric speech signals. Although predictive relationships were complex, vocabulary knowledge, working memory, and cognitive flexibility often emerged as important variables across the models

A Clinical Advantage: Experience Informs Recognition and Adaptation to a Novel Talker With Dysarthria

Purpose: Perceptual training paradigms, which leverage the mechanism of perceptual learning, show that naïve listeners, those with no prior experience with dysarthria, benefit from explicit familiarization with a talker with dysarthria. It is theorized that familiarization affords listeners an opportunity to acquire distributional knowledge of the degraded speech signal. Here, we extend investigations to clinically experienced listeners, speech-language pathologists (SLPs), and advance models of listener recognition and adaptation to dysarthric speech. Method: Forty-seven SLPs completed a standard three-phase perceptual training protocol (pretest, familiarization, and posttest) with a novel talker with dysarthria. Intelligibility scores were compared with historical data from naïve listeners. Potential relationships between intelligibility scores and characteristics of clinical experience were examined. Results: Intelligibility scores of SLPs improved by an average of 19% from pretest to posttest. This intelligibility improvement was lower than naïve listeners, although the difference was small. Moreover, clinical characteristics related to level of dysarthria experience (e.g., percent of caseload composed of dysarthria) predicted pretest/initial intelligibility. No predictive relationships between clinical characteristics and intelligibility improvement were revealed. Conclusions: As a group, SLPs benefitted from perceptual training, suggesting that, despite prior experience, the opportunity to acquire knowledge of talker-specific cue distributions is crucial for optimal adaptation. However, SLPs with greater dysarthria experience were better at initially understanding the talker with dysarthria. This suggests that, through regular interaction with individuals with dysarthria, clinicians acquire knowledge of the cue distributions of dysarthric speech more generally and can generalize this group-specific knowledge to aid in understanding other talkers with dysarthria. Consistent with theoretical models of perceptual learning, both talker- and group-specific knowledge informed recognition and adaptation to dysarthric speech

Regularity Matters: Unpredictable Speech Degradation Inhibits Adaptation to Dysarthric Speech

Listener-targeted perceptual training paradigms, which leverage the mechanism of perceptual learning, show strong promise for improving intelligibility in dysarthria, offsetting the communicative burden from the speaker onto the listener. Theoretical models of perceptual learning underscore the importance of acoustic regularity (i.e., signal predictability) for listener adaptation to degraded speech. The purpose of the current investigation was to evaluate intelligibility outcomes following perceptual training with hyperkinetic dysarthria, a subtype characterized by reduced signal predictability

The Reliability and Validity of Speech-Language Pathologists’ Estimations of Intelligibility in Dysarthria

This study examined the reliability and validity of speech-language pathologists’ (SLP) estimations of speech intelligibility in dysarthria, including a visual analog scale (VAS) method and a percent estimation method commonly used in clinical settings. Speech samples from 20 speakers with dysarthria of varying etiologies were used to collect orthographic transcriptions from naïve listeners n=70 and VAS ratings and percent estimations of intelligibility from SLPs n=21. Intra- and interrater reliability for the two SLP intelligibility measures were evaluated, and the relationship between these measures was assessed. Finally, linear regression was used to evaluate the relationship between the naïve listeners’ orthographic transcription scores and the two SLP intelligibility measures. The results indicated that the intrarater reliability for both SLP intelligibility measures was strong, and the interrater reliability between the SLP ratings was moderate to excellent. A moderate positive relationship between SLPs’ VAS ratings and percent estimations was also observed. Finally, both SLPs’ percent estimations and VAS ratings were predictive of naïve listeners’ orthographic transcription scores, with SLPs’ percent estimations being the strongest predictor. In conclusion, the average SLP percent estimations and VAS ratings are valid and reliable intelligibility measures. However, the validity and reliability of these measures vary between SLPs

Effects of Familiarization on Intelligibility of Dysarthric Speech in Older Adults With and Without Hearing Loss

PURPOSE: Familiarization tasks offer a promising platform for listener-targeted remediation of intelligibility disorders associated with dysarthria. To date, the body of work demonstrating improved understanding of dysarthric speech following a familiarization experience has been carried out on younger adults. The primary purpose of the present study was to examine the intelligibility effects of familiarization in older adults. METHOD: Nineteen older adults, with and without hearing loss, completed a familiarization protocol consisting of three phases: pretest, familiarization, and posttest. The older adults\u27 initial intelligibility and intelligibility improvement scores were compared with previously reported data collected from 50 younger adults (Borrie, Lansford, & Barrett, 2017a). RESULTS: Relative to younger adults, initial intelligibility scores were significantly lower for older adults, although additional analysis revealed that the difference was limited to older adults with hearing loss. Key, however, is that irrespective of hearing status, the older and younger adults achieved comparable intelligibility improvement following familiarization (gain of roughly 20 percentage points). CONCLUSION: This study extends previous findings of improved intelligibility of dysarthria following familiarization to a group of listeners who are critical to consider in listener-targeted remediation, namely, aging caregivers and/or spouses of individuals with dysarthria

Generalized Learning of Dysarthric Speech Between Male and Female Talkers

Purpose Perceptual training is a listener-targeted means for improving intelligibility of dysarthric speech. Recent work has shown that training with one talker generalizes to a novel talker of the same sex and that the magnitude of benefit is maximized when the talkers are perceptually similar. The current study expands previous findings by investigating whether perceptual training effects generalize between talkers of different sex. Method Forty new listeners were recruited for this study and completed a pretest, familiarization, and posttest perceptual training paradigm. Historical data collected using the same three-phase protocol were included in the data analysis. All listeners were exposed to the same talker with dysarthria during the pretest and posttest phases. For the familiarization phase, listeners were exposed to one of four talkers with dysarthria, differing in sex and level of perceptual similarity to the test talker or a control talker. During the testing phases, listener transcribed phrases produced by the test talker with dysarthria. Listener transcriptions were then used to calculate a percent words correct intelligibility score. Results Multiple linear regression analysis revealed that intelligibility at posttest was not predicted by sex of the training talker. Consistent with earlier work, the magnitude of intelligibility gain was greater when the familiarization and test talkers were perceptually similar. Additional analyses revealed greater between-listeners variability in the dissimilar conditions as compared to the similar conditions. Conclusions Learning as a result of perceptual training with one talker with dysarthria generalized to another talker regardless of sex. In addition, listeners trained with perceptually similar talkers had greater and more consistent intelligibility improvement. Together, these results add to previous evidence demonstrating that learning generalizes to novel talkers with dysarthria and that perceptual training is suitable for many listeners