Studies of apraxic speech production

Abstract

A series of five studies of apraxic speakers generated the following conclusions: (1) The major residual errors for an apraxic with ten years of therapy appeared to result from poor temporal coordination of expiration, vocal fold adduction, and articulatory gesture. (2) VOTs for this patient differed markedly from those of normals, and related to perceived voicing errors for stops. (3) VOTs for four other apraxic speakers were also abnormal. (4) Therapy directed toward teaching the first patient to produce more appropriate voice onset times succeeded in establishing two discreet categories of stops, but VOTs still differed from those of normals and lacked “natural quality.” (5) Lack of success in teaching the patient to produce normal stops may result from the categorical perception of clinicians providing feedback for modification. Results of these studies have implications relating to (1) the nature of the apraxic disorder, (2) use of acoustic analysis procedures for diagnosis and management of speech production disorders, (3) limitations of clinician perception in providing feedback for modification of in‐category (distorted) phoneme production errors. [This work was supported in part by NIDR Grant DE‐01774.]