Anecdotally, middle-aged listeners report difficulty conversing in social settings, even when they have normal audiometric thresholds [1-3]. Moreover, young adult listeners with "normal" hearing vary in their ability to selectively attend to speech amid similar streams of speech. Ignoring age, these individual differences correlate with physiological differences in temporal coding precision present in the auditory brainstem, suggesting that the fidelity of encoding of suprathreshold sound helps explain individual differences . Here, we revisit the conundrum of whether early aging influences an individual's ability to communicate in everyday settings. Although absolute selective attention ability is not predicted by age, reverberant energy interferes more with selective attention as age increases. Breaking the brainstem response down into components corresponding to coding of stimulus fine structure and envelope, we find that age alters which brainstem component predicts performance. Specifically, middle-aged listeners appear to rely heavily on temporal fine structure, which is more disrupted by reverberant energy than temporal envelope structure is. In contrast, the fidelity of envelope cues predicts performance in younger adults. These results hint that temporal envelope cues influence spatial hearing in reverberant settings more than is commonly appreciated and help explain why middle-aged listeners have particular difficulty communicating in daily life.
Bibliographical noteFunding Information:
This work was sponsored by the National Institutes of Health (NIDCD R01 DC009477 to B.G.S.-C. and F31 DC011463 to D.R.) and a National Security Science and Engineering Faculty Fellowship (to B.G.S.-C.). We wish to thank Sharon Kujawa for generously taking the time to discuss potential links between our results and the effects of noise exposure and aging on the anatomy and physiology of the auditory pathway.