The Effects of Interactive Context on Acoustic Characteristics of Speech in People With Dysarthria: A Preliminary Study.

PURPOSE: The current study compared temporal and spectral acoustic contrast between vowel segments produced by speakers with dysarthria across three speech tasks-interactive, solo habitual, and solo clear. METHOD: Nine speakers with dysarthria secondary to amyotrophic lateral sclerosis participated in the study. Each speaker was paired with a typical interlocutor over videoconferencing software. The speakers produced the vowels /i, ɪ, ɛ, æ/ in /h/-vowel-/d/ words. For the solo tasks, speakers read the stimuli aloud in both their habitual and clear speaking styles. For the interactive task, speakers produced a target stimulus for their interlocutor to select among the four possibilities. We measured the duration difference between long and short vowels, as well as the F1/F2 Euclidean distance between adjacent vowels, and also determined how well the vowels could be classified based on their acoustic characteristics. RESULTS: Temporal contrast between long and short vowels was higher in the interactive task than in both solo tasks. Spectral distance between adjacent vowel pairs was also higher for some pairs in the interactive task than the habitual speech task. Finally, vowel classification accuracy was highest in the interactive task. CONCLUSIONS: Overall, we found evidence that individuals with dysarthria produced vowels with greater acoustic contrast in structured interactions than they did in solo tasks. Furthermore, the speech adjustments they made to the vowel segments differed from those observed in solo speech.

Comparison of Vowel and Sentence Intelligibility in People With Dysarthria Secondary to Amyotrophic Lateral Sclerosis.

PURPOSE: In this study, we examined the utility of vowel intelligibility testing for assessing the impact of dysarthria on speech characteristics in people with amyotrophic lateral sclerosis (ALS). We tested the sensitivity and specificity of overall vowel identification, as well as that of vowel-specific identification, to dysarthria presence and severity. We additionally examined the relationship between vowel intelligibility and sentence intelligibility. METHOD: Twenty-three people with ALS and 22 age- and sex-matched control speakers produced sentences from the Speech Intelligibility Test (SIT), as well as 10 American English monophthongs in /h/-vowel-/d/ words for the vowel intelligibility test (VIT). Data for SIT and VIT scores came from 135 listeners. Diagnostic accuracy of VIT measures was evaluated using the area under the curve of receiver operator characteristics. We then examined differences between control speakers, speakers with mild dysarthria, and speakers with severe dysarthria in their relationship between SIT and VIT scores. RESULTS: The results suggest that the overall vowel intelligibility score showed high sensitivity and specificity in differentiating between speakers with and without dysarthria, even those with milder symptoms. In addition, single-vowel identification scores showed at least acceptable group differentiation between the mild and severe dysarthria groups, though fewer single vowels were acceptable discriminators between the control group and the group with mild dysarthria. Identification accuracy of /ɪ/ in particular showed excellent discrimination across all groups. Examination of the relationship between SIT and VIT scores suggests a severity-specific relationship. Speakers with SIT scores above 70% generally had higher SIT than VIT scores, whereas speakers with SIT below 70% generally had higher VIT than SIT scores. DISCUSSION: Vowel intelligibility testing can detect speech impairments in speakers with mild dysarthria and residual articulatory function in speakers with severe dysarthria. Vowel intelligibility testing may, therefore, be a useful addition to intelligibility testing for individuals with dysarthria.

Assessment of dysarthria and dysphagia in patients with amyotrophic lateral sclerosis: Review of the current evidence.

Bulbar dysfunction is a common presentation of amyotrophic lateral sclerosis (ALS) and significantly impacts quality of life of people with ALS (PALS). The current paper reviews measurements of dysarthria and dysphagia specific to ALS to identify efficient and valid assessment measures. Using such assessment measures will lead to improved management of bulbar dysfunction in ALS. Measures reviewed for dysarthria in PALS are organized into three categories: acoustic, kinematic, and strength. A set of criteria are used to evaluate the effectiveness of the measures' identification of speech impairments, measurement of functional verbal communication, and clinical applicability. Assessments reviewed for dysphagia in PALS are organized into six categories: patient reported outcomes, dietary intake, pulmonary function and airway defense capacity, bulbar function, dysphagia/aspiration screens, and instrumental evaluations. Measurements that have good potential for clinical use are highlighted in both topic areas. Additionally, areas of improvement for clinical practice and research are identified and discussed. In general, no single speech measure fulfilled all the criteria, although a few measures were identified as potential diagnostic tools. Similarly, few objective measures that were validated and replicated with large sample sizes were found for diagnosis of dysphagia in PALS. Importantly, clinical applicability was found to be limited; thus, a collaborative team focused on implementation science would be helpful to improve the clinical uptake of assessments. Overall, the review highlights the need for further development of clinically viable and efficient measurements that use a multidisciplinary approach.