Marks Kendra L, Siegel Jonathan H
Department of Communication Sciences and Disorders, School of Communication, Northwestern University, 2240 Campus Drive, Evanston, IL, 60208-2952, USA.
J Assoc Res Otolaryngol. 2017 Aug;18(4):529-542. doi: 10.1007/s10162-017-0621-0. Epub 2017 Apr 21.
The response of the inner ear is modulated by the middle ear muscle (MEM) and olivocochlear (OC) efferent systems. Both systems can be activated reflexively by acoustic stimuli delivered to one or both ears. The acoustic middle ear muscle reflex (MEMR) controls the transmission of acoustic signals through the middle ear, while reflex activation of the medial component of the olivocochlear system (the MOCR) modulates cochlear mechanics. The relative prominence of the two efferent systems varies widely between species. Measuring the effect of either of these systems can be confounded by simultaneously activating the other. We describe a simple, sensitive online method that can identify the effects both systems have on otoacoustic emissions (OAEs) evoked by transient stimuli such as clicks or tone pips (TEOAEs). The method detects directly in the time domain the changes in the stimulus and/or emission pressures caused by contralateral noise. Measurements in human participants are consistent with other reports that the threshold for MOCR activation is consistently lower than for MEMR. The method appears to control for drift and subject-generated noise well enough to avoid the need for post hoc processing, making it promising for application in animal experiments (even if awake) and in the hearing clinic.
内耳的反应受中耳肌肉（MEM）和橄榄耳蜗（OC）传出系统的调节。这两个系统都可被传递至一耳或双耳的声刺激反射性激活。声中耳肌肉反射（MEMR）控制声信号通过中耳的传输，而橄榄耳蜗系统内侧部分（MOCR）的反射性激活则调节耳蜗力学。这两个传出系统的相对突出程度在不同物种间差异很大。测量其中任何一个系统的效应都可能因同时激活另一个系统而受到干扰。我们描述了一种简单、灵敏的在线方法，该方法可以识别这两个系统对由咔嗒声或短纯音等瞬态刺激诱发的耳声发射（OAEs）（瞬态诱发耳声发射，TEOAEs）所产生的影响。该方法直接在时域中检测由对侧噪声引起的刺激和/或发射压力的变化。在人类受试者中的测量结果与其他报告一致，即MOCR激活的阈值始终低于MEMR。该方法似乎能很好地控制漂移和受试者产生的噪声，无需进行事后处理，因此有望应用于动物实验（即使是清醒动物）和听力诊所。
