Patterns of Impairments in AOS and Mechanisms of Interaction Between Phonological and Phonetic Encoding PurposeOne reason why the diagnosis of apraxia of speech (AOS) and its underlying impairment are often debated may lie in the fact that most patients do not display pure patterns of AOS. Mixed patterns are clearly acknowledged at other levels of impairment (e.g., lexical–semantic and lexical–phonological), and they have contributed ... Supplement: Apraxia of Speech: Concepts and Controversies
Supplement: Apraxia of Speech: Concepts and Controversies  |   October 01, 2012
Patterns of Impairments in AOS and Mechanisms of Interaction Between Phonological and Phonetic Encoding
 
Author Affiliations & Notes
  • Marina Laganaro
    University of Geneva, Switzerland
  • Correspondence to Marina Laganaro: marina.laganaro@unige.ch
  • Editor: Anne Smith
    Editor: Anne Smith×
  • Associate Editor: Wolfram Ziegler
    Associate Editor: Wolfram Ziegler×
Article Information
Speech, Voice & Prosodic Disorders / Apraxia of Speech & Childhood Apraxia of Speech / Speech, Voice & Prosody / Speech
Supplement: Apraxia of Speech: Concepts and Controversies   |   October 01, 2012
Patterns of Impairments in AOS and Mechanisms of Interaction Between Phonological and Phonetic Encoding
Journal of Speech, Language, and Hearing Research, October 2012, Vol. 55, S1535-S1543. doi:10.1044/1092-4388(2012/11-0316)
History: Received June 4, 2012 , Accepted June 20, 2012
 
Journal of Speech, Language, and Hearing Research, October 2012, Vol. 55, S1535-S1543. doi:10.1044/1092-4388(2012/11-0316)
History: Received June 4, 2012; Accepted June 20, 2012
Web of Science® Times Cited: 8

PurposeOne reason why the diagnosis of apraxia of speech (AOS) and its underlying impairment are often debated may lie in the fact that most patients do not display pure patterns of AOS. Mixed patterns are clearly acknowledged at other levels of impairment (e.g., lexical–semantic and lexical–phonological), and they have contributed to debate about the degree of interaction between encoding levels; by contrast, mixed impairments and mechanisms of interaction are less acknowledged at the levels of phonological and phonetic processes. Here, the author aims at bringing together empirical evidence in favor of an interaction between phonological and phonetic encoding and of the predominance of mixed patterns of impairment over pure phonetic impairment.

MethodThe author reviews empirical results from acoustic and psycholinguistic studies, both with healthy speakers and speakers with brain damage, favoring independent phonological and phonetic encoding and separable impairments as well as recent research pointing to an interaction between phonological and phonetic encoding processes and overlapping patterns of impairments.

ConclusionsAcknowledging interaction between phonological and phonetic processing has clear consequences on the definition of patterns of impairment. In particular, phonetic errors have not necessarily a phonetic origin, and most patterns of impairment are bound to display both phonological and phonetic features.

Acknowledgments
This article originated from a presentation given at the “Apraxia of Speech: Mechanisms and Symptoms” satellite workshop during the 6th International Conference on Speech Motor Control in Groningen, the Netherlands, June 2011. The author is supported by Swiss National Science Foundation Grant N. PP001-118969.
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