Real-Time Audiovisual Feedback Enables Stroke Patients to Reacquire Speech

Aphasia, an impairment in processing language, is one of the most devastating effects of stroke to the left hemisphere of the brain. Recovery from aphasia is often very limited, especially among patients whose speech production is severely limited. Using a new technique, real-time audio-visual speech feedback presented on an iPod, we have shown that aphasic patients can produce fluent speech by mimicking another speaker. This effect is referred to as “speech entrainment.” The effect of speech entrainment can be quite striking and, in some cases, allows patients who have been severely aphasic for decades to produce fluent speech. As importantly, repeated practice with speech entrainment improves spontaneous speech production in patients whose speech output is very minimal. This improvement relies on functional brain changes in cortical areas that integrate audio-visual speech (lip reading) in normal subjects. These findings suggest that the damaged brain recovers the ability to speak by placing greater reliance on intact areas that had a role in speech processing before the initial brain damage occurred.