title: Auditory Masking Effects on Speech Fluency in Apraxia of Speech and Aphasia: Comparison to Altered Auditory Feedback.
abstract: OBJECTIVE
  To study the effects of masked auditory feedback (MAF) on speech fluency in adults with aphasia and/or apraxia of speech (APH/AOS). We hypothesized that adults with AOS would increase speech fluency when speaking with noise. Altered auditory feedback (AAF; i.e., delayed/frequency-shifted feedback) was included as a control condition not expected to improve speech fluency.
  
  
  METHODS
  Ten participants with APH/AOS and 10 neurologically healthy (NH) participants were studied under both feedback conditions. To allow examination of individual responses, we used an ABACA design. Effects were examined on syllable rate, disfluency duration, and vocal intensity.
  
  
  RESULTS
  Seven of 10 APH/AOS participants increased fluency with masking by increasing rate, decreasing disfluency duration, or both. In contrast, none of the NH participants increased speaking rate with MAF. In the AAF condition, only 1 APH/AOS participant increased fluency. Four APH/AOS participants and 8 NH participants slowed their rate with AAF.
  
  
  CONCLUSIONS
  Speaking with MAF appears to increase fluency in a subset of individuals with APH/AOS, indicating that overreliance on auditory feedback monitoring may contribute to their disorder presentation. The distinction between responders and nonresponders was not linked to AOS diagnosis, so additional work is needed to develop hypotheses for candidacy and underlying control mechanisms.
authors.forename: Adam
authors.initials: A
authors.lastname: Jacks
authors.forename: Katarina L
authors.initials: KL
authors.lastname: Haley
mesh_terms: D000161:Acoustic Stimulation; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001037:Aphasia / Q000209:etiology / Q000523:psychology; D001072:Apraxias / Q000209:etiology / Q000523:psychology; D001307:Auditory Perception; D000070642:Brain Injuries, Traumatic / Q000150:complications / Q000523:psychology; D030141:Feedback, Psychological; D056228:Feedback, Sensory; D005260:Female; D006801:Humans; D007807:Language Tests; D008297:Male; D008875:Middle Aged; D011601:Psychophysics; D013060:Speech; D013068:Speech Production Measurement; D020521:Stroke / Q000150:complications / Q000523:psychology