The NIDCD award will provide $300,000 over the next three years to fund the project, titled “Auditory masking effects on speech fluency in aphasia and apraxia of speech.”
In many adults who survive stroke, damage to speech regions of the brain results in a distorted, effortful, and halting pattern of speech, a condition called apraxia of speech. Although they know what they want to say and have intact muscle strength, they have difficulty programming the movements for speech. They are able to hear their speech errors, and the typical treatment program focuses on identifying these errors and correcting them. For most people, focusing on these mistakes results in little improvement in their speech.
In contrast to conventional treatment approaches, Dr. Jacks and his colleagues (Katarina Haley, PhD, DAHS, DSHS; Heidi Roth, MD, Department of Neurology) are studying the effects of preventing the person with apraxia of speech from hearing the errors in their speech, by playing loud noise through earphones. This approach is based on the premise that people with this speech disorder are overly-attuned to speech errors, which prevents them from speaking fluently. The same phenomenon has been known for decades to help people who stutter to speak fluently, as demonstrated in the popular film The King's Speech.
In the proposed research, Dr. Jacks and his colleagues seek to identify stroke survivors who respond positively to listening to noise by increasing speech rate and decreasing the occurrence of speech disfluencies (pauses, filler words, repetitions). Since not all people are expected to show a change in speech while listening to noise, the team also will study individual characteristics to determine what differentiates those who improve from those who do not. In particular, behavioral profiles (type of speech and language impairment) and location and size of brain lesion will be compared between positive responders and non-responders to determine whether a positive response can be predicted from routine clinical data.
In preliminary work, over half of the participants tested spoke more quickly and with fewer disfluencies while listening to noise. Although this is a temporary effect and does not persist after the noise is turned off, the moments of speech fluency experienced may cause the person's brain to activate in a different way than it does when he or she is speaking disfluently. If the preliminary results are borne out in the completed study, Dr. Jacks and his team believe that the procedure may be further developed into a useful therapeutic technique that can result in lasting speech changes.