The central nervous system (CNS) closely monitors auditory feedback during speech production. This monitoring process is critical for learning to produce speech and maintaining the speech production system. Moreover, stuttering and several speech disorders are associated with deficits in monitoring. Thus, understanding neural mechanisms of speech monitoring is critical for development and refinement of theories of speech production and stuttering, as well as, for development of theory-driven treatments. Current models of speech have focused entirely on monitoring processes during speech production and do not explain if and how the CNS optimizes the auditory system prior to speech initiation for speech monitoring. Such modulatory mechanisms are especially fundamental to the understanding of stuttering, as most stuttering events occur on the initial sound/syllable of words, highlighting deficient preparatory mechanisms in stuttering individuals. This program of research aims at elucidating predictive modulatory mechanisms occurring before speech initiation. We hypothesize that the CNS uses an active process in which motor predictions optimally adjust the auditory system prior to speech initiation for effective speech monitoring. By combining electroencephalography (EEG) and speech acoustics in the context of innovative experimental paradigms, we propose a program of research to study three main aspects of the phenomenon of pre-speech modulation that will have immediate theoretical and long-term clinical implications. The proposed studies will a) substantially expand our knowledge of predictive mechanisms that optimize speech monitoring, and b) inform theories of speech production by providing a (currently missing) account of how the CNS optimizes the auditory system to accomplish effective speech monitoring. Importantly, given our previous reports of lack of pre-speech modulation in individuals who stutter, this program of research will provide a strong foundation for a follow-up R01 proposal to examine contributions of pre-speech sensory modulation in neurobiological bases of stuttering. Finally, our findings will pave the way for completely novel therapeutics techniques (e.g., neuro-feedback training and noninvasive neuro-stimulation) that specifically target pre-speech modulation as a promising neural target.
Speech monitoring is the most important mechanism for learning to produce speech during childhood and maintaining the speech production system throughout adulthood. The proposed studies will elucidate predictive mechanisms that tune the auditory system for effective speech monitoring. Findings of this project will inform theories of speech production and form a strong foundation to develop highly innovative and theory-driven treatments for speech disorders.