Apraxia of Speech (AOS)

Acquired apraxia of speech is a neurogenic speech disorder that is characterized by:

  • erroneous production of speech sounds
  • reduced rate of speech
  • increased time in transitioning between sounds, syllables, and words
  • disordered prosody

May be accompanied by:

  • articulatory groping
  • difficulty initiating speech
  • increasing number of sound errors with increasing word length
  • motoric perseverations

Severity ranges from a complete inability to speak to minimal disruptions in speech production.

Primary Clinical Characteristics:

    • Slow speech rate:
      • Lengthened segments (vowels and/or consonants)
      • Lengthened intersegment durations (between sounds, syllables, words, phrases: possibly filled with intrusive schwa)
    • Sound distortions (including consonants and vowels)
    • Distorted sound substitutions

Errors are relatively consistent in type (e.g. substitution, omission, distortion) and location in repeated utterances

  • Prosodic Abnormalities

Nondiscriminative Clinical Characteristics (can occur with phonemic paraphasias):

  • Articulatory groping: audible and/or visible and probably disordered relative to the target
  • Perseverative errors (perseverations of movement patterns)
  • Increasing errors with increasing word length
  • Speech initiation difficulties
  • Awareness of errors
  • Automatic speech better than propositional speech
  • Islands of error free speech


  • Ballard, K. J., Wambaugh, J. L., Duffy, J. R., Layfield, C., Maas, E., Mauszycki, S., & McNeil, M. R. (2015). Treatment for acquired apraxia of speech: A systematic review of intervention research between 2004 and 2012. American Journal of Speech-Language Pathology, 24(2), 316-337
  • Duffy, J. R. (2013). Motor speech disorders: Substrates, differential diagnosis, and management. Elsevier Health Sciences.

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