Haywood Nicholas R, Undurraga Jaime A, Marquardt Torsten, McAlpine David
UCL Ear Institute, UCL School of Life and Medical Sciences, University College London, UK
UCL Ear Institute, UCL School of Life and Medical Sciences, University College London, UK.
Trends Hear. 2015 Dec 30;19:2331216515619039. doi: 10.1177/2331216515619039.
There has been continued interest in clinical objective measures of binaural processing. One commonly proposed measure is the binaural interaction component (BIC), which is obtained typically by recording auditory brainstem responses (ABRs)-the BIC reflects the difference between the binaural ABR and the sum of the monaural ABRs (i.e., binaural - (left + right)). We have recently developed an alternative, direct measure of sensitivity to interaural time differences, namely, a following response to modulations in interaural phase difference (the interaural phase modulation following response; IPM-FR). To obtain this measure, an ongoing diotically amplitude-modulated signal is presented, and the interaural phase difference of the carrier is switched periodically at minima in the modulation cycle. Such periodic modulations to interaural phase difference can evoke a steady state following response. BIC and IPM-FR measurements were compared from 10 normal-hearing subjects using a 16-channel electroencephalographic system. Both ABRs and IPM-FRs were observed most clearly from similar electrode locations-differential recordings taken from electrodes near the ear (e.g., mastoid) in reference to a vertex electrode (Cz). Although all subjects displayed clear ABRs, the BIC was not reliably observed. In contrast, the IPM-FR typically elicited a robust and significant response. In addition, the IPM-FR measure required a considerably shorter recording session. As the IPM-FR magnitude varied with interaural phase difference modulation depth, it could potentially serve as a correlate of perceptual salience. Overall, the IPM-FR appears a more suitable clinical measure than the BIC.
对双耳听觉处理的临床客观测量方法一直存在持续的研究兴趣。一种常见的测量方法是双耳相互作用成分（BIC），它通常通过记录听觉脑干反应（ABR）来获得——BIC反映了双耳ABR与单耳ABR之和之间的差异（即双耳-（左耳+右耳））。我们最近开发了一种替代的、直接测量双耳时间差敏感度的方法，即对双耳相位差调制的跟随反应（双耳相位调制跟随反应；IPM-FR）。为了获得这个测量值，会呈现一个持续的双耳调幅信号，并且载波的双耳相位差在调制周期的最小值处周期性切换。这种对双耳相位差的周期性调制可以诱发一个稳态跟随反应。使用16通道脑电图系统对10名听力正常的受试者进行了BIC和IPM-FR测量的比较。ABR和IPM-FR在相似的电极位置观察得最为清晰——从耳部附近的电极（如乳突）相对于头顶电极（Cz）进行差分记录。尽管所有受试者都显示出清晰的ABR，但BIC并未得到可靠观察。相比之下，IPM-FR通常会引发强烈且显著的反应。此外，IPM-FR测量所需的记录时间要短得多。由于IPM-FR的幅度随双耳相位差调制深度而变化，它有可能作为感知显著性的一个相关指标。总体而言。IPM-FR似乎是比BIC更合适的临床测量方法。
