Speech intelligibility in ALS and HD dysarthria: The everyday listener's perspective

The purpose of this study was to examine the barriers and strategies that listeners endorsed as they attempted to understand dysarthric speech. Speech samples were collected from individuals with amyotrophic lateral sclerosis (ALS) (N = 6) and Huntington disease (HD) (N = 6). Sentences varied in length from 5-15 words and were selected to reflect reduced speech intelligibility. Two 4-point equal interval scales, one for barriers and one for strategies, were developed based on information collected from four focus groups of listeners. Everyday listeners (N = 37) completed the two scales after transcribing samples of ALS and HD dysarthria. Results indicated that barriers to intelligibility and strategies for listening varied as a function of dysarthria type and that listeners distinguished between dysarthria types based on barriers to intelligibility. Listeners highly endorsed many strategies and used both bottom-up and top-down strategies to understand dysarthric speech. Findings of this study highlight the listener as an important factor to consider when researching speech intelligibility in dysarthria. Future research should be extended to include other types of dysarthria and listener groups along with the cognitive demands of attempting to understand dysarthric speech.