Rhythm and Pitch differences between speakers with Dysarthria and Control speakers

Abstract

Dysarthria is a motor speech disorder characterised by impaired articulation, slow speaking rate, voice disturbances, and rhythm disturbances. As a result, dysarthric speech is perceived by listeners to have poor intelligibility. While the factors above are widely claimed to be contributing to its lack of intelligibility, the focus of most research has solely been on articulation and speaking rate. This thesis aimed to investigate what the rhythmic and pitch variation are between adult Dutch speakers with dysarthria and a control group. Rhythm metrics were used as a measure for rhythm and pitch variation as a measure for pitch to try to identify where these disturbances lie. Speaker recordings were available from a corpus (COPAS) and selected if all speakers read a common text. Speech durations were extracted, and rhythm and pitch measures calculated. The results showed that no group significance between the dysarthric and control group, but sentence effects were significant for speech rate, rhythm metrics, and pitch variation between the dysarthric and control group. There was also one group and sentence interaction between the dysarthric and control group for one of the rhythm metrics (VarcoV). However, there was no significance found for speech rate, rhythm metrics and pitch variation within the dysarthric group. These results form part of preliminary groundwork in adding to the understanding of rhythm disturbances in dysarthria and suggest future research in optimising diagnosis using rhythm metrics and thereby, treatment.