Detection of middle-ear muscle reflex activation using changes in otoacoustic emission stimulus amplitude versus absorbance: an initial investigation

The medial olivocochlear reflex (MOCR) reduces cochlear amplifier gain, which may be beneficial for hearing in noise. Additionally, measurement of the MOCR may be diagnostically useful in the audiology clinic. The MOCR can be measured as the change in transient-evoked otoacoustic emission (TEOAE) amplitude without versus with contralateral acoustic stimulation (CAS). However, CAS can activate the middle-ear muscle reflex (MEMR) which can confound the MOCR results. MEMR activation has been assessed using changes in TEOAE stimulus amplitude without versus with CAS. As an initial investigation, the current study compared detection of MEMR activation using changes in TEOAE stimulus amplitude to changes in wideband absorbance. In 26 normal-hearing participants, the MEMR was measured as the change in absorbance and as the change in TEOAE stimulus amplitude without and with CAS. Percentile critical differences were developed from the test-retest measurements. Measures of agreement between MEMR detection methods were computed. CAS resulted in a larger number of participants exceeding the 95th percentile critical difference for absorbance compared to TEOAE stimulus amplitude (22 versus 1). Agreement between methods was low. Initial results indicated that MEMR was detectable in a larger number of participants when using absorbance compared to TEOAE stimulus amplitude. However, future work could better equate the two methods and include measurement of MEMR thresholds to determine optimal methods for detecting MEMR activation during MOCR assessments.

内侧橄榄耳蜗反射（medial olivocochlear reflex, MOCR）可降低耳蜗放大器增益，该效应或有助于改善噪声环境下的听力。此外，MOCR的检测在听力学临床中具备诊断应用价值。MOCR的检测可通过对比无对侧声刺激（contralateral acoustic stimulation, CAS）与施加CAS时的瞬态诱发性耳声发射（transient-evoked otoacoustic emission, TEOAE）振幅变化来实现。但CAS可激活中耳肌反射（middle-ear muscle reflex, MEMR），进而干扰MOCR的检测结果。既往研究多通过对比有无CAS时的TEOAE刺激振幅变化，来评估MEMR的激活情况。作为一项初步探索性研究，本研究对比了采用TEOAE刺激振幅变化与宽带吸光度变化两种方案检测MEMR激活的效果。本研究纳入26名听力正常受试者，分别通过吸光度变化与TEOAE刺激振幅变化两种指标，测量了有无CAS条件下的MEMR响应。研究基于重测数据推导得到了百分位临界差，并计算了两种MEMR检测方法间的一致性指标。结果显示，相较于TEOAE刺激振幅指标，采用吸光度指标时，有更多受试者的检测结果超出95%百分位临界差（分别为22例与1例）。两种检测方法间的一致性较低。初步结果表明，相较于TEOAE刺激振幅，采用吸光度检测可在更多受试者中检出MEMR激活。不过，未来研究可进一步优化两种检测方法的等效性，并加入MEMR阈值测量环节，以确定在MOCR评估中检测MEMR激活的最优方案。