Toward Phonetic Intelligibility Testing in Dysarthria

TLDR

Intelligibility measurement in dysarthria is a key clinical and research concern, yet it is a relative metric influenced by test material, personnel, training, procedures, and speaker state, prompting the development of a profile to guide acoustic and physiological investigations. The study reviews existing sealing procedures and item identification tests for dysarthric speech and proposes a new word intelligibility test. The proposed test evaluates 19 acoustic‑phonetic contrasts expected to be sensitive to dysarthric impairment and to influence speech intelligibility. Preliminary data from ALS patients demonstrate how the test can be used to interpret phonetic contributions to intelligibility impairment.

Abstract

The measurement of intelligibility in dysarthric individuals is a major concern in clinical assessment and management and in research on dysarthria. The measurement objective is complicated by the fact that intelligibility is not an absolute quantity but rather a relative quantity that depends on variables such as test material, personnel, training, test procedures, and state of the speaker. This paper reviews sealing procedures and item identification tests as they have been applied to dysarthric speech. Based in part on previous studies of speech of the hearing impaired, a profile has been designed to direct research on the acoustic or physiologic correlates of dysarthric intelligibility impairment. In addition, a word intelligibility test is proposed for use with dysarthric speakers. This test is designed to examine 19 acoustic-phonetic contrasts that are likely to (a) be sensitive to dysarthric impairment and (b) contribute significantly to speech intelligibility. Preliminary data from a sample of subjects with amyotrophic lateral sclerosis are presented to illustrate the use of this test in the phonetic interpretation of intelligibility impairment.