[Brainmap] Hari Bharadwaj, PhD, Title: When normal hearing is not enough -- Individual differences in auditory selective attention

Wednesday, April 15, 2015 - 00:00 to 13:00

Wednesday 4/15/2015 at 12:00 noon

Seminar room 2204

149 13th St., Charlestown Navy Yard

 

 

Abstract: The ability to selectively attend to a sound source of interest while ignoring irrelevant sounds is vital to everyday communication. In contrast to quiet backgrounds, listening in noisy/multi-talker settings (dubbed "cocktail-party" listening) places enormous demands on the auditory system. Accordingly, under laboratory conditions, large and reliable individual differences in performance are seen in cocktail-party tasks even among listeners with no known hearing complaints. In this talk, I will describe a series of experiments that exploit these individual differences to understand the mechanisms that contribute our selective attention ability. Using otoacoustic emissions, electrophysiological measures and neuroimaging, we probed the human auditory system at the peripheral, subcortical and cortical levels of the auditory pathway. Our results show that even among listeners with audiologically normal hearing, considerable variability is found in the fidelity with which subcortical structures encode sounds. Independently, individual differences are also seen in the efficacy of cortical control in selecting the encoded target sounds from competing maskers. Across listeners, measures of both subcortical coding and cortical control correlate with performance. Interpreted in conjunction with animal and computational models, these findings help understand the mechanisms by which middle-aged listeners and those with a history of acoustic overexposure experience difficulty under cocktail-party conditions. The implications for clinical practice and some future directions to study social-communication deficits, including in developmental disorders, will be discussed.