Automatic Control, Department of Electrical Engineering, Linköping University, 581 83 Linköping, Sweden
Eriksholm Research Centre, DK-3070 Snekkersten, Denmark.
eNeuro. 2024 Aug 27;11(8). doi: 10.1523/ENEURO.0135-24.2024. Print 2024 Aug.
The auditory brainstem response (ABR) is a measure of subcortical activity in response to auditory stimuli. The wave V peak of the ABR depends on the stimulus intensity level, and has been widely used for clinical hearing assessment. Conventional methods estimate the ABR average electroencephalography (EEG) responses to short unnatural stimuli such as clicks. Recent work has moved toward more ecologically relevant continuous speech stimuli using linear deconvolution models called temporal response functions (TRFs). Investigating whether the TRF waveform changes with stimulus intensity is a crucial step toward the use of natural speech stimuli for hearing assessments involving subcortical responses. Here, we develop methods to estimate level-dependent subcortical TRFs using EEG data collected from 21 participants listening to continuous speech presented at 4 different intensity levels. We find that level-dependent changes can be detected in the wave V peak of the subcortical TRF for almost all participants, and are consistent with level-dependent changes in click-ABR wave V. We also investigate the most suitable peripheral auditory model to generate predictors for level-dependent subcortical TRFs and find that simple gammatone filterbanks perform the best. Additionally, around 6 min of data may be sufficient for detecting level-dependent effects and wave V peaks above the noise floor for speech segments with higher intensity. Finally, we show a proof-of-concept that level-dependent subcortical TRFs can be detected even for the inherent intensity fluctuations in natural continuous speech.
听觉脑干反应（ABR）是一种针对听觉刺激的皮质下活动的测量方法。ABR 的波 V 峰值取决于刺激强度水平，已被广泛用于临床听力评估。传统方法估计 ABR 平均脑电图（EEG）对短而不自然的刺激（如点击）的响应。最近的工作已经朝着使用更具生态相关性的连续语音刺激方向发展，使用称为时间响应函数（TRF）的线性反卷积模型。研究 TRF 波形是否随刺激强度而变化是将自然语音刺激用于涉及皮质下反应的听力评估的关键步骤。在这里，我们开发了使用从 21 名参与者收集的 EEG 数据来估计依赖于水平的皮质下 TRF 的方法，这些参与者听以 4 种不同强度水平呈现的连续语音。我们发现，几乎所有参与者的皮质下 TRF 的波 V 峰值都可以检测到依赖于水平的变化，并且与点击 ABR 波 V 的依赖于水平的变化一致。我们还研究了最适合生成依赖于水平的皮质下 TRF 预测器的外围听觉模型，发现简单的伽马通滤波器组表现最佳。此外，对于具有较高强度的语音段，可能只需要大约 6 分钟的数据即可检测到依赖于水平的效应和高于噪声底的波 V 峰值。最后，我们展示了一个概念验证，即使对于自然连续语音中的固有强度波动，也可以检测到依赖于水平的皮质下 TRF。
