A long-standing puzzle is why listeners with normal hearing thresholds show such enormous variation in performance on other auditory tasks. Differences among normal hearing listeners are particularly pronounced when tasks involve separating multiple sound sources, such as when listeners must rely on selective auditory attention. Recent animal work shows that noise exposure can damage the synaptic efficacy of auditory nerve fibers without permanently altering hearing thresholds, producing auditory neuropathy. Low-spontaneous rate auditory nerve fibers, which are especially important for encoding the temporal content of supra-threshold sound, may be preferentially affected. Consistent with animal studies, our preliminary results in listeners with normal thresholds suggest that inter-subject performance differences on selective attention tasks correlate with psychophysical and physiological measures designed to reveal the fidelity of temporal coding at supra-threshold levels. We hypothesize that auditory neuropathy may be much more common than previously recognized: young listeners with normal hearing thresholds may differ in the fidelity with which their auditory nerve fibers encode supra-threshold temporal information, affecting their ability to communicate in everyday settings. Sound exposure leads to supra-threshold deficits in animals without threshold shifts; thus, we also postulate that listeners with conventionally defined hearing loss from noise exposure likely also suffer from supra-threshold deficits that contribute substantially to communication difficulties. The main objective of this project is to quantify auditory neuropathy in a cohort of young, normal hearing listeners. We will also explore how supra-threshold encoding contributes to performance differences in listeners with elevated thresholds due to noise exposure. We will:
Aim 1) characterize individual differences in supra-threshold sound encoding in subcortical portions of the auditory pathway;
Aim 2) characterize individual differences in the ability to selectively attend, and relate them to differences in coding fidelity;
and Aim 3) characterize how supra-threshold sound encoding fidelity contributes to performance differences for listeners with mild to moderate high-frequency hearing loss. We will compare physiological (brainstem responses, distortion product otoacoustic emissions, and cortical responses) and behavioral measures from the same listeners and use computational models to unravel the relationships between these metrics. Our results will quantify how peripheral encoding of supra-threshold sound differs across listeners with both normal and elevated thresholds, and will establish how supra-threshold differences affect the ability to communication in common social settings. Our results could lead to a clinical test of supra-threshold hearing fidelity, quantifying one factor leading to differences in communication ability amongst listeners with similar audiograms.

Public Health Relevance

Listeners who have 'normal' hearing (i.e., whose detection thresholds fall in the normal range) vary greatly in some perceptual abilities, especially those that require them to focus selective auditory attention. This project explores whether some of the variations in hearing outcome that cannot be explained by hearing detection thresholds arise due to differences in the fidelity of supra-threshold temporal coding. The proposed work could point the way towards new clinical tests that quantify differences in peripheral hearing not captured by threshold measures, ultimately leading to new interventions and remediation strategies that are better tailored to individual listeners' hearing status.

National Institute of Health (NIH)
National Institute on Deafness and Other Communication Disorders (NIDCD)
Research Project (R01)
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Auditory System Study Section (AUD)
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Donahue, Amy
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Boston University
Engineering (All Types)
Biomed Engr/Col Engr/Engr Sta
United States
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Dai, Lengshi; Best, Virginia; Shinn-Cunningham, Barbara G (2018) Sensorineural hearing loss degrades behavioral and physiological measures of human spatial selective auditory attention. Proc Natl Acad Sci U S A 115:E3286-E3295
Mehraei, Golbarg; Shinn-Cunningham, Barbara; Dau, Torsten (2018) Influence of talker discontinuity on cortical dynamics of auditory spatial attention. Neuroimage 179:548-556
Bressler, Scott; Goldberg, Hannah; Shinn-Cunningham, Barbara (2017) Sensory coding and cognitive processing of sound in Veterans with blast exposure. Hear Res 349:98-110
Mehraei, Golbarg; Gallardo, Andreu Paredes; Shinn-Cunningham, Barbara G et al. (2017) Auditory brainstem response latency in forward masking, a marker of sensory deficits in listeners with normal hearing thresholds. Hear Res 346:34-44
Shinn-Cunningham, Barbara (2017) Cortical and Sensory Causes of Individual Differences in Selective Attention Ability Among Listeners With Normal Hearing Thresholds. J Speech Lang Hear Res 60:2976-2988
Baumgartner, Robert; Reed, Darrin K; Tóth, Brigitta et al. (2017) Asymmetries in behavioral and neural responses to spectral cues demonstrate the generality of auditory looming bias. Proc Natl Acad Sci U S A 114:9743-9748
Haghighi, Marzieh; Moghadamfalahi, Mohammad; Akcakaya, Murat et al. (2017) A Graphical Model for Online Auditory Scene Modulation Using EEG Evidence for Attention. IEEE Trans Neural Syst Rehabil Eng 25:1970-1977
Kop?o, Norbert; Andrejková, Gabriela; Best, Virginia et al. (2017) Streaming and sound localization with a preceding distractor. J Acoust Soc Am 141:EL331
Noyce, Abigail L; Cestero, Nishmar; Michalka, Samantha W et al. (2017) Sensory-Biased and Multiple-Demand Processing in Human Lateral Frontal Cortex. J Neurosci 37:8755-8766
Mehraei, Golbarg; Hickox, Ann E; Bharadwaj, Hari M et al. (2016) Auditory Brainstem Response Latency in Noise as a Marker of Cochlear Synaptopathy. J Neurosci 36:3755-64

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