Effects of alphabet-supplemented speech on brain activity of listeners: An fMRI study.

J Speech Lang Hear Res. 2015 Aug 7;

Authors: Fercho K, Baugh LA, Hanson EK

Abstract
Purpose: To examine the neural mechanisms associated with increases in speech intelligibility brought about through alphabet supplementation.
Method: Neurotypical participants listened to dysarthric speech while watching an accompanying video of a hand pointing to the first letter spoken of each word on an alphabet display (treatment condition) or a scrambled display (control condition). Their hemodynamic response was measured with fMRI, using a sparse sampling event-related paradigm. Speech intelligibility was assessed via a forced-choice auditory identification task throughout the scanning session.
Results: Alphabet supplementation was associated with significant increases in speech intelligibility. Further, alphabet supplementation increased activation in brain regions known to be involved in both auditory speech and visual letter perception above that seen with the scrambled display. Significant increases in functional activity were observed within the posterior to mid superior temporal sulcus (STS)/superior temporal gyrus (STG) during alphabet supplementation, regions known to be involved in speech processing and audiovisual integration.
Conclusion: Alphabet supplementation is an effective tool for increasing the intelligibility of degraded speech and is associated with changes in activity within audiovisual integration sites. Changes in activity within the STS/STG may be related to the behavioral increases in intelligibility brought about by this augmented communication method.

PMID: 26254449 [PubMed - as supplied by publisher]