Changes over time in dysarthric patients with amyotrophic lateral sclerosis (ALS): a study of changes in speaking rate and maximum repetition rate (MRR)

Two cases of amyotrophic lateral sclerosis (ALS) were investigated over time, from a point when speech intelligibility is still at a high level until oral communication becomes almost impossible. Speech intelligibility, speaking rate, and maximum repetition rate (MRR) were examined. Great declines in speaking rate and MRR were observed over time. In addition, both speaking rate and MRR were considerably slower when compared to the control group even when speech intelligibility was still high. The latter finding indicates these parameters are more sensitive in reflecting functional changes in articulators, rather than speech intelligibility, at the early stage of the disease. These results are discussed in terms of an assessment and management system for ALS speakers.