Speech entrainment, a treatment method that requires participants to mimic the speech of an audiovisual model in real time, has been shown to benefit individuals with non-fluent aphasia when they speak about trained topics. It is unclear if it improves spontaneous speech, which does not pertain to trained items, in the same way. In an effort to investigate this matter, the current study examined the effects of speech entrainment on spontaneous speech that does not relate to trained items, it also estimated effect sizes associated with improvements in speech production as a result of this treatment approach, and explored participant characteristics associated with treatment response. Twenty participants were recruited to participate in this study. Each participant received three weeks of treatment and underwent extensive speech and language testing before and after treatment had concluded, as well as testing of discourse abilities pre-treatment, post treatment, at three months post treatment and again at six months post-treatment.
We found that speech entrainment treatment does in fact improve spontaneous speech for some people with non-fluent aphasia. The number of words and different words per minute in participants’ speech samples did not increase for everybody, but the accuracy of the information content that the participants uttered was found to increase significantly. Notably, there was also a significant positive change in aphasia quotient scores, picture naming, semantic processing and grammatical processing.
Analysis of functional brain activity supported previous findings of the importance of pMTG for speech entrainment and how changes in activity could predict changes in both fluency and informativeness of spontaneous speech output