Prosody in apraxia of speech.

Prosody is a complex process that involves modulation of pitch, loudness, duration, and linearity in the acoustic stream to serve linguistic and affective communication goals. It arises from the interaction of distributed neural networks that may be anatomically and functionally lateralized. Intrinsic prosody is mediated largely through left hemisphere mechanisms and encompasses those elements of linguistic microstructure (e.g., syllabic magnitudes and durations, basic consonantal and vocalic gesture specifications, and so) that yield the segmental aspects of speech. Extrinsic prosody is processed primarily by right hemisphere (RH) mechanisms and involves manipulation of intonation across longer perceptual groupings. Intrinsic prosody deficits can lead to several core symptoms of speech apraxia such as difficulty with utterance initiation and syllable transitionalization and may lead to the establishment of inappropriate syllable boundaries. The intrinsic prosody profiles associated with acquired apraxia of speech, developmental speech apraxia, and ataxic dysarthria may aid in the clinical differentiation of these disorders.