Acoustic Patterns of Apraxia of Speech

TLDR

Apraxia of speech is a controversial disorder thought to involve motor‑programming deficits, evidenced by higher‑order phonological errors and articulatory dyscoordination that suggest substantial neural damage. The study acoustically characterizes speech in seven apraxia of speech patients without severe aphasia and interprets the observed error patterns within a spatial‑temporal motor control framework. Acoustic analysis revealed slow, irregular speech with prolonged transitions, reduced intensity variation, articulatory incoordination, initiation problems, and segment selection or sequencing errors.

Abstract

Apraxia of speech (or verbal apraxia) is a controversial disorder, considered by some to be an impairment of the motor programming of speech. Because the disorder is characterized by "higher orderrdquo; errors such as metathesis and segment addition as well as by errors of apparent dyscoordination of articulation, it seems to reflect a relatively high level of damage to the nervous system. This report presents acoustic descriptions of the speech of seven persons diagnosed as having apraxia of speech but without severe aphasic impairmaent, especially agrammatism. The acoustic results indicate a variety of segmental and prosodic atmormalities, including slow speaking rate with prolongations of transitions, steady states, and intersyllable pauses; reduced intensity variation across syllables; slow and inaccurate movements of the articulators; incoordination of voicing with other articulations; initiation difficulties; and errors of selection or sequencing of segments. These error patterns are discussed with respect to a theory of motor control based on spatial-temporal schemata. In addition, consideration is given to the controversy about phonologic versus motor programming impairment in apraxia of speech.