Manchester Centre for Audiology and Deafness, Division of Human Communication, Development & Hearing, School of Health Sciences, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, University of Manchester, United Kingdom.
Department of Communication and Swallowing Disorders, King Fahad Medical City, Riyadh, Saudi Arabia.
Ear Hear. 2019 May/Jun;40(3):659-670. doi: 10.1097/AUD.0000000000000648.
The aims of this study were to systematically explore the effects of stimulus duration, background (quiet versus noise), and three consonant-vowels on speech-auditory brainstem responses (ABRs). Additionally, the minimum number of epochs required to record speech-ABRs with clearly identifiable waveform components was assessed. The purpose was to evaluate whether shorter duration stimuli could be reliably used to record speech-ABRs both in quiet and in background noise to the three consonant-vowels, as opposed to longer duration stimuli that are commonly used in the literature. Shorter duration stimuli and a smaller number of epochs would require shorter test sessions and thus encourage the transition of the speech-ABR from research to clinical practice.
Speech-ABRs in response to 40 msec [da], 50 msec [ba] [da] [ga], and 170 msec [ba] [da] [ga] stimuli were collected from 12 normal-hearing adults with confirmed normal click-ABRs. Monaural (right-ear) speech-ABRs were recorded to all stimuli in quiet and to 40 msec [da], 50 msec [ba] [da] [ga], and 170 msec [da] in a background of two-talker babble at +10 dB signal to noise ratio using a 2-channel electrode montage (Cz-Active, A1 and A2-reference, Fz-ground). Twelve thousand epochs (6000 per polarity) were collected for each stimulus and background from all participants. Latencies and amplitudes of speech-ABR peaks (V, A, D, E, F, O) were compared across backgrounds (quiet and noise) for all stimulus durations, across stimulus durations (50 and 170 msec) and across consonant-vowels ([ba], [da], and [ga]). Additionally, degree of phase locking to the stimulus fundamental frequency (in quiet versus noise) was evaluated for the frequency following response in speech-ABRs to the 170 msec [da]. Finally, the number of epochs required for a robust response was evaluated using Fsp statistic and bootstrap analysis at different epoch iterations.
Background effect: the addition of background noise resulted in speech-ABRs with longer peak latencies and smaller peak amplitudes compared with speech-ABRs in quiet, irrespective of stimulus duration. However, there was no effect of background noise on the degree of phase locking of the frequency following response to the stimulus fundamental frequency in speech-ABRs to the 170 msec [da]. Duration effect: speech-ABR peak latencies and amplitudes did not differ in response to the 50 and 170 msec stimuli. Consonant-vowel effect: different consonant-vowels did not have an effect on speech-ABR peak latencies regardless of stimulus duration. Number of epochs: a larger number of epochs was required to record speech-ABRs in noise compared with in quiet, and a smaller number of epochs was required to record speech-ABRs to the 40 msec [da] compared with the 170 msec [da].
This is the first study that systematically investigated the clinical feasibility of speech-ABRs in terms of stimulus duration, background noise, and number of epochs. Speech-ABRs can be reliably recorded to the 40 msec [da] without compromising response quality even when presented in background noise. Because fewer epochs were needed for the 40 msec [da], this would be the optimal stimulus for clinical use. Finally, given that there was no effect of consonant-vowel on speech-ABR peak latencies, there is no evidence that speech-ABRs are suitable for assessing auditory discrimination of the stimuli used.
本研究旨在系统探讨刺激时长、背景（安静与噪声）以及三个辅音-元音对言语听觉脑干反应（ABR）的影响。此外，评估记录具有清晰可辨波形成分的言语 ABR 所需的最小 epoch 数量。目的是评估较短时长的刺激是否可以在安静和背景噪声下可靠地用于记录三个辅音-元音的言语 ABR，而不是文献中常用的较长时长的刺激。较短时长的刺激和较少的 epoch 将需要更短的测试时间，从而鼓励言语 ABR 从研究过渡到临床实践。
12 名听力正常的成年人在经过确认的正常点击 ABR 后，对 40 毫秒[da]、50 毫秒[ba][da][ga]和 170 毫秒[ba][da][ga]刺激的 40 毫秒[da]、50 毫秒[ba][da][ga]和 170 毫秒[da]进行了单耳（右耳）言语 ABR 记录。在 +10dB 信噪比的双说话者 babble 背景下，使用 2 通道电极导联（Cz 主动、A1 和 A2 参考、Fz 接地）记录所有刺激和安静条件下的 40 毫秒[da]、50 毫秒[ba][da][ga]和 170 毫秒[da]的单耳言语 ABR。所有参与者在每个刺激和背景下收集了 12000 个 epoch（每个极性 6000 个）。比较了所有刺激时长、50 毫秒和 170 毫秒时长以及[ba]、[da]和[ga]三个辅音-元音的背景（安静和噪声）下言语 ABR 峰潜伏期和峰振幅。此外，还评估了 170 毫秒[da]言语 ABR 中频率跟随反应的刺激基频相位锁定程度（在安静和噪声下）。最后，使用 Fsp 统计量和引导分析在不同的 epoch 迭代中评估了获得稳健反应所需的 epoch 数量。
背景效应：与安静条件下的言语 ABR 相比，加入背景噪声会导致言语 ABR 具有更长的峰潜伏期和更小的峰振幅，无论刺激时长如何。然而，背景噪声对 170 毫秒[da]言语 ABR 中刺激基频的频率跟随反应的相位锁定程度没有影响。时长效应：50 毫秒和 170 毫秒刺激的言语 ABR 峰潜伏期和振幅没有差异。辅音-元音效应：无论刺激时长如何，不同的辅音-元音对言语 ABR 峰潜伏期都没有影响。epoch 数量：与安静条件相比，在噪声中记录言语 ABR 需要更多的 epoch，而与 170 毫秒[da]相比，记录 40 毫秒[da]需要更少的 epoch。
这是第一项系统研究言语 ABR 在刺激时长、背景噪声和 epoch 数量方面的临床可行性的研究。即使在背景噪声下，也可以可靠地记录 40 毫秒[da]的言语 ABR，而不会影响响应质量。由于 40 毫秒[da]所需的 epoch 较少，因此这将是临床应用的最佳刺激。最后，由于辅音-元音对言语 ABR 峰潜伏期没有影响，因此没有证据表明言语 ABR 适用于评估所用刺激的听觉辨别能力。
