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Speech & Hearing Science :: University of Illinois at Urbana-Champaign

The Department of Speech & Hearing Science
College of Applied Health Sciences

Research

Typical Speech Production

Recent research in the NeuroSpeech lab has focused on how sensory feedback is used for speech production and oral motor control. We have made some important gains in understanding normal fluency and how speech movements change under altered auditory feedback.

  • We first discovered that auditory feedback is very important for maintaining fluent speech in certain persons who would be considered normal speakers. Auditory feedback is the sound of our own voice that we use to monitor the pitch and loudness of our own voice. In a large group of speakers, we identified that delaying auditory feedback caused some speakers to become highly disfluent, while other speakers could maintain typical fluency. This important advance reported by Chon et al., (accepted – 2012) shows there is a continuum of speech motor skills among typical speakers.
  • This led to a second experiment, which indicated that typical speakers modify their speech movements when auditory feedback is delayed slightly. These movement compensations to altering feedback indicate the auditory-motor system responds specifically to slight alterations in feedback (Chon, HC, Doctoral Dissertation).
  • Ongoing work is leading to knowledge of how auditory feedback is used to learn new motor patterns. In one publication, we showed participants were able to learn how to match very fine lip and finger movements to specific auditory patterns (Loucks et al., 2010). One interesting result is that older participants (over 65 years) seem to have more difficulty learning this auditory-to-motor task.
  • Other studies are directed towards understanding how movement control changes with age and how auditory feedback influences language learning.

Stuttering

One of the most exciting findings from the NeuroSpeech Lab is that adults who stutter are affected by auditory feedback in a different manner than typical adults.

  • Adults who stutter are less sensitive to their own auditory feedback when speaking. Using the important pitch-shift paradigm we found that adults who stutter do not adapt their pitch to changing feedback conditions as much as typical adult speakers. It suggests that internal neural mechanisms that correct for ‘speech errors’ are less sensitive in adults who stutter (Loucks et al., 2012).
  • When auditory feedback is slightly delayed however, the speech movements of adults who stutter can become more stable. It suggests adults who stutter have a higher dependency on intact auditory feedback when speaking (Chon, HC, Doctoral Dissertation).
  • Ongoing studies of brain differences in adults who stutter suggest that connections between the left and right hemispheres are altered compared to typical adults (Choo et al., 2011, 2012). An upcoming set of studies will test if auditory evoked potentials are altered in persons who stutter.

Auditory feedback is thus opening a window into the nature of stuttering, which will provide insight into more effective treatments.

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