What can vowel acoustics reveal about the communicative participation of people living with ALS?

Objective: Bulbar dysfunction often diminishes the accuracy and speed of the tongue, lip, and jaw movements necessary for speech production. Vowel acoustic features derived from speech recordings can serve as sensitive markers of articulatory accuracy and movement timing. We examined whether degraded speech caused by amyotrophic lateral sclerosis (ALS), assessed through vowel acoustic features, was associated with communicative participation restrictions. As a secondary aim, we assessed the association of two global speech characteristics, rate and intelligibility, with vowel features and communicative participation. Materials & Methods: Thirty-three people with ALS (plwALS) recorded a reading passage and completed surveys using a smartphone application. Speaking rate and acoustic vowel features (duration, vowel articulation index [VAI]) were extracted from the recordings. Three speech-language pathologists rated speech intelligibility. Communicative participation was assessed using the Communicative Participation Item Bank (CPIB) short form. Bivariate correlation, partial correlation, and regression analyses were used to evaluate the associations between vowel features, intelligibility, speaking rate, and CPIB scores. Results: Significant bivariate correlations, ranging from r_s = -0.39 to r_s = 0.64, were found between speech variables and CPIB scores. A combined regression model including VAI, vowel duration, and sex explained 52% of the variance in CPIB scores. Including speaking rate or intelligibility in the partial correlation analysis attenuated the associations between vowel acoustics and CPIB. Conclusions: Vowel features and global dysarthria characteristics are linked to communicative participation in ALS. Clinical practices designed to target vowel production, speaking rate, and intelligibility may help to maintain daily communication in ALS.