Sensorimotor learning plays a critical role in the acquisition and refining of all skilled movements, including speech production. From early babbling to fully mature speech articulation, the central nervous system acquires and updates neural representations of the intricate motor-to-auditory transformations that take place from the generation of motor commands to vocal tract movements and speech sound output. Moreover, auditory-motor learning - the process through which such neural representations are learned and maintained - is believed to play an important role in the etiology of developmental speech disorders such as stuttering and childhood apraxia of speech. This series of six integrated experiments therefore seeks to gain a better understanding of the principles and mechanisms involved in speech sensorimotor learning in general and in auditory-motor learning in particular. The overall program of research is designed around the dual short-term goals of (a) optimizing the rate and extent of auditory-motor adaptation, and (b) minimizing the rate and extent of de-adaptation (decay of sensorimotor learning). The findings from these studies will also elucidate the developmental progression of auditory-motor learning during childhood as well as differences in auditory-motor learning between children and adults. Furthermore, given that the core experimental paradigm for auditory-motor adaptation studies causes speakers to automatically alter their speech output in a short period of time, without instruction, and without effort, one long-term goal of the proposed research program is to develop novel, computer-assisted clinical procedures that induce adaptive changes in speech motor behavior by systematically altering the speaker's auditory feedback. Thus, this work's direct relevance to public health lies in the fact that the generated knowledge will contribute directly to an in-depth understanding of typical speech development, the maintenance of speech articulation skills throughout the lifespan, and fundamental sensorimotor mechanisms underlying developmental speech disorders, while simultaneously paving the way for highly innovative clinical techniques for the treatment of a wide variety of speech disorders.
This series of studies will contribute to a better understanding of how the brain learns the articulatory movements involved in speech production and how it remains able to adjust those movements based on hearing our own speech sounds. Adaptive behavioral changes related to neural plasticity are studied in the speech of children and adults. The knowledge gained form this work will make it possible to improve theoretical models of the processes involved in speech sensorimotor learning and to pursue new directions of research on the etiology of developmental speech disorders in which sensorimotor learning may be impaired. In addition, the research findings will suggest innovative techniques for treating speech disorders in children and adults.
| Daliri, Ayoub; Max, Ludo (2018) Stuttering adults' lack of pre-speech auditory modulation normalizes when speaking with delayed auditory feedback. Cortex 99:55-68 |
| Maruthy, Santosh; Feng, Yongqiang; Max, Ludo (2018) Spectral Coefficient Analyses of Word-Initial Stop Consonant Productions Suggest Similar Anticipatory Coarticulation for Stuttering and Nonstuttering Adults. Lang Speech 61:31-42 |
| Feng, Yongqiang; Xiao, Yan; Yan, Yonghong et al. (2018) Adaptation in Mandarin tone production with pitch-shifted auditory feedback: Influence of tonal contrast requirements. Lang Cogn Neurosci 33:734-749 |
| Mitsuya, Takashi; Munhall, Kevin G; Purcell, David W (2017) Modulation of auditory-motor learning in response to formant perturbation as a function of delayed auditory feedback. J Acoust Soc Am 141:2758 |
| Max, Ludo; Maffett, Derek G (2015) Feedback delays eliminate auditory-motor learning in speech production. Neurosci Lett 591:25-9 |
