Communication efficiency of dysarthric speakers as measured by sentence intelligibility and speaking rate

In an effort to quantify communication efficiency, speaking rates and intelligibility scores were obtained from a normal speaking adult and 13 dysarthric speakers representing a wide range of severity. Speakers were audio recorded as they read words and sentences. A panel of judges transcribed all recordings and subjectively ranked a randomly selected sample from each speaker according to "communication efficiency." The following measures were obtained for each speaker: word and sentence intelligibility, speaking rate, rates of intelligible and unintelligible speech and a numerical ranking of communication efficiency. Results indicated that speaking rate and speech intelligibility are not closely correlated. By plotting measures that incorporate intelligibility and rate, one can rank speakers similarly to subjective rankings of communication efficiency, and distinguish mildly dysarthric from normal speakers. The addition of intelligibility and rate measures to supplement other assessment procedures in the evaluation of dysarthric speakers is discussed.