Treating control of voicing in apraxia of speech with variable practice

Kirrie J. Ballard, Edwin Maas, Donald A. Robin

Research output: Contribution to journalArticle

34 Citations (Scopus)

Abstract

Background: Apraxia of speech (AOS) is generally considered a phonetic-motoric disorder. As such, it is reasonable to draw on the motor learning literature to develop interventions for improving articulation. The often cited problem of impaired voicing control is used to test the application of a variable practice approach to training skilled movements in AOS. It is predicted that variable practice - practising a behaviour over a range of possible values or contexts - increases accuracy and stability of a trained behaviour. Aims: The aims of the study were to test the influence of variable practice conditions on acquisition and long-term maintenance of voiced and voiceless phonemes in words at the phrase/sentence level as well as on generalisation of treatment effects to phonemes of same and different manner. The protocol was tested on two individuals with moderate AOS, one of whom exhibited a concomitant moderate aphasia. Methods & Procedures: A single subject multiple baseline across-subjects design was used to examine efficacy of treatment for improving control of voicing for three fricative/affricate phonemes (Participant 1) or three plosive phonemes (Participant 2). The training sets included two voiced phonemes and one voiceless phoneme, each presented in the initial position of 10 different words. This provided a range of voice onset times and a range of phonetic contexts for each target phoneme, thus providing the variable practice. The inclusion of a voiceless phoneme that was produced at a high level of accuracy during baseline was hypothesised to reduce the chance of overgeneralisation from voiced to voiceless phoneme production. Outcomes & Results: Consistent with predictions, participants demonstrated improved production of trained voiced phonemes and generalisation of treatment effects to untrained phonemes of same manner only. These effects were maintained up to 3 months post-treatment. Results support training multiple fricatives or plosives in parallel in a variety of phonetic contexts (i.e., variable practice) as well as including a combination of voiced and voiceless phonemes in treatment to ensure maintenance of accurate voiceless phoneme production. Conclusions: Results from two participants, varying in overall communication impairment severity, provide promising evidence that a variable practice approach to retraining speech behaviours in AOS is effective. Specifically, this approach resulted in long-term maintenance of treatment effects and generalisation of treatment effects to untrained phonemes within manner class. Just as importantly, it did not result in overgeneralisation of voicing to voiceless phonemes. Further testing is required before recommending general clinical application.

Original languageEnglish (US)
Pages (from-to)1195-1217
Number of pages23
JournalAphasiology
Volume21
Issue number12
DOIs
StatePublished - Dec 2007
Externally publishedYes

Fingerprint

Apraxias
Phonetics
phonetics
Training Support
Aphasia
retraining
speech disorder
Communication
Maintenance
Apraxia of Speech
Phoneme
Voicing
Learning
inclusion
communication
learning
evidence
Values

Keywords

  • Apraxia of speech
  • Motor learning
  • Variable practice
  • Voice onset time

ASJC Scopus subject areas

  • Clinical Neurology
  • Neurology

Cite this

Treating control of voicing in apraxia of speech with variable practice. / Ballard, Kirrie J.; Maas, Edwin; Robin, Donald A.

In: Aphasiology, Vol. 21, No. 12, 12.2007, p. 1195-1217.

Research output: Contribution to journalArticle

Ballard, Kirrie J. ; Maas, Edwin ; Robin, Donald A. / Treating control of voicing in apraxia of speech with variable practice. In: Aphasiology. 2007 ; Vol. 21, No. 12. pp. 1195-1217.
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