Department of Speech, Language, and Hearing Sciences, University of Connecticut, Storrs, Connecticut, United States.
Institute for the Brain and Cognitive Sciences, University of Connecticut, Storrs, Connecticut, United States.
J Neurophysiol. 2024 Sep 1;132(3):1074-1084. doi: 10.1152/jn.00297.2023. Epub 2024 Jul 31.
Listeners exhibit varying levels of tolerance for background noise during speech communication. It has been proposed that low tolerance of background noise may be the consequence of abnormally amplified gain in the central auditory system (CAS). Here, using a dataset of young adults with normal hearing thresholds, we asked whether central gain mechanisms might also explain cases of hypertolerance of background noise, as well as cases of reduced, but not abnormal, tolerance. We used the auditory brainstem response to derive a measure of CAS gain (wave V/wave I ratio) to compare listeners' background noise tolerance while listening to speech, grouping them into three categories: hyper, high, and medium tolerance. We found that hypertolerant listeners had reduced CAS gain compared to those with high tolerance. This effect was driven by wave V not wave I. In addition, the medium tolerant listeners trended toward having reduced wave I and reduced wave V amplitudes and generally higher levels of exposure to loud sound, suggestive of the early stages of noise-compromised peripheral function without an apparent compensatory increase in central gain. Our results provide physiological evidence that ) reduced CAS gain may account for hypertolerance of background noise but that ) increased CAS gain is not a prerequisite for medium tolerance of background noise. Our findings strengthen the proposed mechanistic connection between background noise tolerance and auditory physiology by suggesting a link between hypertolerance and reduced central auditory gain, measured by the auditory brainstem response.
听众在言语交流过程中对背景噪声的容忍度存在差异。有人提出，对背景噪声的低容忍度可能是中枢听觉系统（CAS）增益异常放大的结果。在这里，我们使用一组听力正常的年轻成年人数据集，询问中枢增益机制是否也可以解释背景噪声超敏的情况，以及降低但未异常的容忍度的情况。我们使用听觉脑干反应来得出 CAS 增益的度量（波 V/波 I 比），以比较听众在听言语时的背景噪声容忍度，将他们分为三组：超敏、高敏和中敏。我们发现，与高容忍度的听众相比，超敏度的听众的 CAS 增益降低。这种效应是由波 V 而不是波 I 驱动的。此外，中敏听众的波 I 和波 V 振幅趋于降低，并且通常暴露在强噪声下的水平较高，提示在没有明显的中枢增益补偿增加的情况下，噪声受损的外围功能处于早期阶段。我们的结果提供了生理证据，表明）降低的 CAS 增益可能是背景噪声超敏的原因，但）增加的 CAS 增益不是背景噪声中敏容忍度的先决条件。我们的发现通过听觉脑干反应测量，增强了背景噪声容忍度与听觉生理学之间的拟议机制联系，表明超敏与中枢听觉增益降低之间存在联系。
