Department of Hearing and Speech Sciences, Vanderbilt University Medical Center, Nashville, TN, USA.
Current Affiliation: Collaborative for STEM Education and Outreach, Peabody College of Education, Vanderbilt University, Nashville, TN, USA.
J Assoc Res Otolaryngol. 2022 Dec;23(6):859-873. doi: 10.1007/s10162-022-00872-0. Epub 2022 Oct 10.
The middle-ear system relies on a balance of mass and stiffness characteristics for transmitting sound from the external environment to the cochlea and auditory neural pathway. Phase is one aspect of sound that, when transmitted and encoded by both ears, contributes to binaural cue sensitivity and spatial hearing. The study aims were (i) to investigate the effects of middle-ear stiffness on the auditory brainstem neural encoding of phase in human adults with normal pure-tone thresholds and (ii) to investigate the relationships between middle-ear stiffness-induced changes in wideband acoustic immittance and neural encoding of phase. The auditory brainstem neural encoding of phase was measured using the auditory steady-state response (ASSR) with and without middle-ear stiffness elicited via contralateral activation of the middle-ear muscle reflex (MEMR). Middle-ear stiffness was quantified using a wideband acoustic immittance assay of acoustic absorbance. Statistical analyses demonstrated decreased ASSR phase lag and decreased acoustic absorbance with contralateral activation of the MEMR, consistent with increased middle-ear stiffness changing the auditory brainstem neural encoding of phase. There were no statistically significant correlations between stiffness-induced changes in wideband acoustic absorbance and ASSR phase. The findings of this study may have important implications for understanding binaural cue sensitivity and horizontal plane sound localization in audiologic and otologic clinical populations that demonstrate changes in middle-ear stiffness, including cochlear implant recipients who use combined electric and binaural acoustic hearing and otosclerosis patients.
中耳系统依赖质量和刚度特性的平衡，将声音从外部环境传递到耳蜗和听觉神经通路。相位是声音的一个方面，当双耳传输和编码时，它有助于双耳线索敏感性和空间听觉。研究目的是：（i）研究中耳刚度对正常纯音阈值成人听觉脑干神经相位编码的影响；（ii）研究中耳刚度引起的宽带声导抗与相位编码变化之间的关系。使用听觉稳态反应（ASSR）测量相位的听觉脑干神经编码，同时通过对中耳肌肉反射（MEMR）的对侧激活来引出中耳刚度。使用宽带声导抗测定法测量声吸收来定量中耳刚度。统计分析表明，随着 MEMR 的对侧激活，ASSR 相位滞后和声吸收减少，这与中耳刚度增加改变听觉脑干神经相位编码一致。宽带声吸收的刚度诱导变化与 ASSR 相位之间没有统计学上显著的相关性。这项研究的结果可能对理解双耳线索敏感性和水平平面声音定位具有重要意义，这些研究对象在中耳刚度发生变化的情况下表现出听力和耳科学临床人群中，包括使用电和双耳声学听力的耳蜗植入者和耳硬化症患者。
