Acoustic differences in emotional speech of people with dysarthria

Communicating emotion is essential in building and maintaining relationships. We communicate our emotional state not just with the words we use, but also how we say them. Changes in the rate of speech, short-term energy and intonation all help to convey emotional states like 'angry', 'sad' and 'happy'. People with dysarthria, the most common speech disorder, have reduced articulatory and phonatory control. This can affect the intelligibility of their speech, especially when communicating with unfamiliar conversation partners. However, we know little about how people with dysarthria convey their emotional state, and whether they are having to make changes to their speech to achieve this. In this study, we investigated the ability of people with dysarthria, caused by cerebral palsy and Parkinson's disease, to communicate emotions in their speech, and we compared their speech to that of speakers with typical speech. A parallel database of emotional speech was collected. One female speaker with dysarthria due to cerebral palsy, 3 speakers with dysarthria due to Parkinson's disease (2 female and 1 male), and 21 typical speakers (9 female and 12 male) produced sentences with 'angry', 'happy', 'sad', and 'neutral' emotions. A number of acoustic features were analysed using linear multi-level modeling. The results show that people with dysarthria were able to control some aspects of the suprasegmental and prosodic features when attempting to communicate emotions. For most speakers the changes they made are consistent with the changes made by speakers with typical speech. Even when the changes might be different to that of typical speakers, acoustic analysis shows these were consistent for different emotions. The analysis shows that variation in energy and jitter (local absolute) are major indicators of emotion in the study.