We recently showed that listeners with normal hearing thresholds vary in their ability to direct spatial attention and that ability is related to the fidelity of temporal coding in the brainstem. Here, we recruited additional middle-aged listeners and extended our analysis of the brainstem response, measured using the frequency-following response (FFR). We found that even though age does not predict overall selective attention ability, middle-aged listeners are more susceptible to the detrimental effects of reverberant energy than young adults. We separated the overall FFR into orthogonal envelope and carrier components and used an existing model to predict which auditory channels drive each component. We find that responses in mid- to high-frequency auditory channels dominate envelope FFR, while lower-frequency channels dominate the carrier FFR. Importantly, we find that which component of the FFR predicts selective attention performance changes with age. We suggest that early aging degrades peripheral temporal coding in mid-to-high frequencies, interfering with the coding of envelope interaural time differences. We argue that, compared to young adults, middle-aged listeners, who do not have strong temporal envelope coding, have more trouble following a conversation in a reverberant room because they are forced to rely on fragile carrier ITDs that are susceptible to the degrading effects of reverberation.
|Title of host publication
|Basic Aspects of Hearing
|Subtitle of host publication
|Physiology and Perception
|Springer Science and Business Media, LLC
|Number of pages
|Published - 2013
|Advances in Experimental Medicine and Biology
Bibliographical noteFunding Information:
This work was sponsored by the National Institutes of Health (NIDCD R01 DC009477 to BGSC and NIDCD F31DC011463 to DR) and the National Security Science and Engineering Faculty Fellowship to BGSC.