Acoustic Correlates of Prosodic Abnormality in Acquired Apraxia of Speech

Abstract

Abstract Purpose: Prosodic abnormality is one of the primary characteristics used for the perceptual differentiation between acquired apraxia of speech (AOS) and phonemic paraphasias in the context of fluent aphasia. Acoustic measures of speech prosody are not frequently used in the clinical assessment of AOS, but would be useful as a method of quantifying prosodic abnormality. The purpose of this paper is to describe acoustic characteristics of prosodic abnormality in adult speakers with AOS. Method: Previous investigations of acoustic measures of speech prosody in AOS were reviewed, focusing on studies of duration, fundamental frequency (F0), and speech intensity. Results and Conclusions: Prosodic abnormality in adults with AOS is primarily characterized by articulatory prolongation. In some individuals, relational patterns among syllables are retained despite overall increased duration, while others produce syllables that are temporally isolated, giving the impression that speech is programmed one syllable at a time. Syllable segregation is also noted in F0 and intensity contours that lack continuity across syllables. Metrics are suggested for use in quantification of prosodic abnormality in AOS. The review of findings, particularly slowed speech rate, is interpreted in the context of theoretical models of speech including impaired or intact feedback mechanisms in speakers with AOS.