This study investigates the role of the motor system in speech perception using an adaptive task that isolates perception from decision-making. EEG signatures of motor activity (sensorimotor μ/beta suppression) were examined during the perception of auditory phonemes, auditory words, audiovisual words, and environmental sounds at two difficulty levels. Results showed left-lateralized sensorimotor μ/beta suppression related to speech perception but not environmental sounds. Audiovisual word and phoneme perception showed enhanced suppression for correct trials, while auditory word perception showed enhanced suppression for incorrect trials. These findings suggest a flexible engagement of motor areas in speech perception, depending on the stimulus characteristics and impacting perceptual outcomes differently.

Kelly Michaelis, Makoto Miyakoshi, Gina Norato, Andrei V. Medvedev, Peter E. Turkeltaub