Toward an acoustic typology of motor speech disorders.

Acoustic methods have progressed to the point that an acoustic typology of the motor speech disorders can be constructed from a parameteric assessment of the speech subsystems (e.g., phonation, nasal resonance, vowel articulation, consonant articulation, intonation, and rhythm). The results of this analysis can be interpreted in respect to global functions in speech (e.g., voice quality, intelligibility, and prosody). This paper reviews studies showing that specific acoustic analyses have demonstrated or potential value toward the overall goal of constructing acoustic profiles of dysarthria and apraxia of speech. Several different acoustic measures are relevant to the study of the motor speech disorders, and these are increasingly supported by normative data and by guidelines for clinical application. Examples of these applications are discussed for a variety of specific neurologic diseases or perceptual types of disorder. Acoustic studies are useful in the study of motor speech disorders and recent progress points to a parametric analysis.