Delayed Auditory Feedback

Summer 2003

(American Academy of Neurology-) Researchers in New Orleans have identified a subset of stutterers that may benefit most from delayed auditory feedback (a technique by which the original acoustic speech signal is artificially modified and then fed back via headphones). Findings of their study were presented at the American Academy of Neurology annual meeting in Honolulu in April.

Delayed auditory feedback (DAF) has been shown to induce fluency in many individuals who stutter, though not all stutterers experience enhanced fluency by this technique. The primary aim of this study was to learn if there is a relationship between the anatomy of the auditory association cortex (planum temporale) and fluency induced with DAF in adults with persistent developmental stuttering. The planum temporale is a brain structure important in processing auditory information.

A study group of 14 adults with this type of stuttering disorder and 14 control subjects read prose passages three times: at baseline, with non-altered feedback, and with DAF. Three measures of fluency were evaluated: stuttering event frequency, severity, and reading time.

"We found a subgroup of adults with atypical rightward planum temporale asymmetry, who were more disfluent at baseline and had fluency induced with DAF," noted study author Anne Foundas, MD, of Tulane University in New Orleans, LA. "How-ever, deficits in auditory processing cannot account for stuttering in all people who stutter, because we identified another subgroup of adults who had typical leftward planum temporale asymmetry and who did not become more fluent with DAF."

This study was supported by the NIH, the Charles A. Dana Foundation, and the Department of Veterans Affairs South Central MIRECC.