Grand Rounds Seminar

Abstract: Speech sounds are acoustically complex, temporally ephemeral signals that are rapidly and robustly categorized by the human brain into discrete, talker-independent linguistic units that support communication. My research program examines how the brain represents speech, how cortical speech representations change with age, and how these changes relate to emerging clinical challenges. Using intracranial and noninvasive recordings, we have shown that early auditory cortical areas encode abstract phonemic and prosodic categories independent of their acoustic form. In middle-aged adults with clinically normal audiograms, these representations become less distinct, less stable, and more diffusely distributed, consistent with the neural dedifferentiation hypothesis of aging. This “fuzzier” encoding of speech sounds is linked to sensory and cortical changes that are not reflected in standard hearing assessments. Building on these mechanistic insights, we are developing a brief, noninvasive, EEG-based assessment that uses naturalistic speech and neural network decoding to detect subtle deficits in speech sound encoding. In both animal models and human studies, this approach reveals robust neural markers of subclinical, age-related changes in speech processing, offering a path toward earlier identification and targeted intervention. Our translational efforts focus on adapting the assessment for routine clinical use, reducing test time, validating it on standard audiology equipment, and ensuring sensitivity across diverse patient populations. This talk illustrates how our computational and systems neuroscience approach can bridge the gap from laboratory discovery to clinical application, with the potential to transform hearing healthcare for individuals whose difficulties are currently undetected and untreated.

About: Dr. Bharath Chandrasekaran, PhD, is the Ralph and Jean Sundin Professor and Chair of the Roxelyn and Richard Pepper Department of Communication Sciences and Disorders at Northwestern University. Prior to Northwestern, he served as a Professor and Vice Chair of Research in the Department of Communication Sciences and Disorders. My research examines the neurobiological computations that underlie human communication and learning, using an interdisciplinary, computational, and lifespan approach. His laboratory is currently supported by funding from the National Institutes of Health and National Science Foundation. He earned his Ph.D. in Integrative Neuroscience from Purdue University in 2008, completed a postdoctoral fellowship at Northwestern University before joining the University of Texas at Austin in 2010. He is the recipient of Regents’ Outstanding Teaching Award in 2014, the Editor’s award for best research article in the Journal of Speech, Language, and Hearing Research, the Psychonomics Early Career award in 2016, the Society for Neurobiology of Language Early Career Award in 2018, and the Fellowship of the American Speech-Language Hearing Association in 2022. Dr. Chandrasekaran has previously served as the Editor-in-Chief of the Journal of Speech, Language, and Hearing Research (Speech) and the Chair of the Language and Communication Study Section for the National Institutes of Health. Dr. Chandrasekaran’s research examines the neurobiological computations that underlie human communication and learning, using an interdisciplinary, computational, and lifespan approach. His laboratory is currently supported by funding from the National Institutes of Health and National Science Foundation.