Hearing Technology @ WAVES, Department of Information Technology, Ghent University, Technologiepark 126, Zwijnaarde, 9052, Belgium.
Medizinische Physik and Cluster of Excellence Hearing4all, Department of Medical Physics and Acoustics, University of Oldenburg, Carl-von-Ossietzky Strasse 9-11, 26120, Oldenburg, Germany.
Hear Res. 2020 Jul;392:107979. doi: 10.1016/j.heares.2020.107979. Epub 2020 Apr 29.
The envelope following response (EFR) has been proposed as a non-invasive marker of synaptopathy in animal models. However, its amplitude is affected by the spread of basilar-membrane excitation and other coexisting sensorineural hearing deficits. This study aims to (i) improve frequency specificity of the EFR by introducing a derived-band EFR (DBEFR) technique and (ii) investigate the effect of lifetime noise exposure, age and outer-hair-cell (OHC) damage on DBEFR magnitudes. Additionally, we adopt a modelling approach to validate the frequency-specificity of the DBEFR and test how different aspects of sensorineural hearing loss affect peripheral generators. The combined analysis of simulations and experimental data proposes that the DBEFRs extracted from the [2-6]-kHz frequency band is a sensitive and frequency-specific measure of synaptopathy in humans. Individual variability in DBEFR magnitudes among listeners with normal audiograms was explained by their self-reported amount of experienced lifetime noise-exposure and corresponded to amplitude variability predicted by synaptopathy. Older listeners consistently had reduced DBEFR magnitudes in comparison to young normal-hearing listeners, in correspondence to how age-induced synaptopathy affects EFRs and compromises temporal envelope encoding. To a lesser degree, OHC damage was also seen to affect the DBEFR magnitude, hence the DBEFR metric should ideally be combined with a sensitive marker of OHC damage to offer a differential diagnosis of synaptopathy in listeners with impaired audiograms.
随声反应后的信封（EFR）已被提议作为动物模型中突触病的一种非侵入性标志物。然而，其幅度受到基底膜兴奋传播和其他共存的感觉神经性听力缺陷的影响。本研究旨在（i）通过引入衍生频带 EFR（DBEFR）技术来提高 EFR 的频率特异性，（ii）研究终身噪声暴露、年龄和外毛细胞（OHC）损伤对 DBEFR 幅度的影响。此外，我们采用建模方法来验证 DBEFR 的频率特异性，并测试不同类型的感觉神经性听力损失如何影响外围发生器。模拟和实验数据的综合分析表明，从[2-6]kHz 频带中提取的 DBEFR 是一种敏感且具有频率特异性的人类突触病测量指标。具有正常听力图的听众中 DBEFR 幅度的个体差异可以用他们报告的终生噪声暴露量来解释，并且与突触病预测的幅度变化相对应。与年轻的正常听力听众相比，老年听众的 DBEFR 幅度始终较低，这与年龄引起的突触病如何影响 EFR 并损害时间包络编码相对应。在较小程度上，也观察到 OHC 损伤会影响 DBEFR 幅度，因此 DBEFR 指标理想情况下应与 OHC 损伤的敏感标志物相结合，以对听力图受损的听众中的突触病进行鉴别诊断。
