Biomedical Engineering, Boston University, 610 Commonwealth Ave, Boston, MA 02215, USA.
Speech, Language, and Hearing Sciences, Purdue University, Lyles-Porter Hall, 715 Clinic Dr., West Lafayette, IN 47907, USA.
Neuroscience. 2019 May 21;407:67-74. doi: 10.1016/j.neuroscience.2019.02.003. Epub 2019 Mar 1.
Previous studies suggest that envelope-following responses (EFRs) reveal important differences in temporal coding fidelity amongst listeners who have normal hearing thresholds, consistent with these listeners differing in the degree to which they suffer from cochlear synaptopathy. Like conventional hearing loss, the severity of cochlear synaptopathy may vary along the cochlea. A number of earlier studies have suggested methods for estimating EFRs driven by specific frequency regions of the cochlea, which would allow synaptopathy to be estimated as a function of cochlear place. Here, we tested a method for measuring EFRs from multiple locations along the cochlea simultaneously, using narrowband stimuli. We compared responses to multiple simultaneous narrowband complex harmonic tones in three non-overlapping frequency bands, each having a unique fundamental frequency, to responses to the individual narrowband stimuli alone, and to responses when noise was added to different combinations of the frequency bands. Our results suggest that simultaneous presentation of multiple tone complexes with different fundamental frequencies leads to repeatable measures of temporal coding fidelity at the cochlear frequency regions corresponding to the narrowband carrier frequencies. Other results suggested that while off-frequency contributions to EFRs driven by narrowband signals (due to spread of excitation) can add destructively to the on frequency response, these interactions were small compared to EFR magnitude. Overall, our results point to the utility of using multi-band complex tone stimuli to estimate the profile of temporal coding fidelity, and thus the degree of synaptopathy, as a function of cochlear place. This article is part of a Special Issue entitled: Hearing Loss, Tinnitus, Hyperacusis, Central Gain.
先前的研究表明，包络跟随反应（EFRs）揭示了具有正常听力阈值的听众在时间编码保真度方面的重要差异，这与他们受耳蜗突触病影响的程度不同有关。与传统听力损失一样，耳蜗突触病的严重程度可能沿耳蜗而变化。许多早期的研究提出了估计耳蜗特定频率区域驱动的 EFRs 的方法，这将允许将突触病作为耳蜗位置的函数进行估计。在这里，我们使用窄带刺激测试了一种同时测量耳蜗多个位置 EFRs 的方法。我们比较了对多个同时的窄带复音谐波在三个不重叠的频带中的响应，每个频带都有独特的基频，与单独的窄带刺激的响应以及噪声添加到不同频带组合时的响应。我们的结果表明，同时呈现具有不同基频的多个音复合体可在与窄带载波频率相对应的耳蜗频率区域中得到可重复的时间编码保真度测量。其他结果表明，尽管窄带信号驱动的 EFRs 的非频带贡献（由于激励的扩展）可能会对频带响应产生破坏性影响，但与 EFR 幅度相比，这些相互作用很小。总体而言，我们的结果表明，使用多频带复音刺激来估计时间编码保真度的分布，从而评估突触病的程度，这是耳蜗位置的函数，具有实用性。本文是一个题为“听力损失、耳鸣、听觉过敏、中枢增益”的特刊的一部分。
