Title: Neural Systems Supporting Speech Categorization and Category Learning

Abstract: Speech categorization is a core computational problem for the auditory system: transforming multidimensional, variable, and rapidly unfolding acoustic input into stable linguistic units that support efficient communication. This talk will describe the neural infrastructure that enables speech categorization in adults, and how that infrastructure supports the acquisition of novel categories later in life. I will first present converging evidence from intracranial and non-invasive recordings that early auditory cortical circuits encode category-level structure that is not reducible to the surface acoustics, providing a stable multidimensional representational scaffold for perception. I will then show that the distinctiveness and stability of these neural category representations shift with aging even when clinical hearing is normal, suggesting changes in how categories are maintained and deployed across the lifespan. Finally, I will discuss how adults learn novel speech categories, and how learning reshapes neural representations over time through interactions among sensory encoding, prior experience, and cognitive control. I will highlight sources of individual differences in category learning success, including variability in sensory precision, neural representational stability, attentional control, and the efficiency of integrating feedback over time.

Bio: Dr. Bharath Chandrasekaran is the Ralph and Jean Sundin Professor and Chair of the Roxelyn and Richard Pepper Department of Communication Sciences and Disorders at Northwestern University. He earned his Ph.D. in Integrative Neuroscience from Purdue University and completed a postdoctoral fellowship at Northwestern. His research, funded by the National Institutes of Health and the National Science Foundation, investigates the neurobiological computations underlying human communication and learning.

Interests: Auditory Processing, Language Learning and Processing, Neuroscience, Scientific Collaboration