INTELLIGIBILITY AND THE ACOUSTIC CHARACTERISTICS OF SPEECH IN AMYOTROPHIC-LATERAL-SCLEROSIS (ALS)

The purpose of this study was to analyze the changes in specific speec h parameters in 14 patients, 7 dysarthric and 7 non-dysarthric, with a myotrophic lateral sclerosis (ALS), over a 6-month period. Measurement s of single word intelligibility, F2 formant trajectories (extent, dur ation and rate) and diadochokinetic rate showed decreased performance in dysarthric patients as compared to non-dysarthric patients at basel ine. F2 transition rates of less than 4 Hz/msec were seen only in dysa rthric ALS patients. A relationship between the F2 transition rate and single word intelligibility was noted for patients with moderate to h igh intelligibility, but at lower levels of intelligibility the F2 rat e reached a plateau despite continued decline in intelligibility. Our results support the need for frequent evaluation of dysarthric ALS pat ients to better understand the relationship between intelligibility an d the acoustic parameters of speech.