Department of Hearing and Speech Sciences, Vanderbilt University, School of Medicine, Nashville, TN 37232, USA.
Department of Hearing and Speech Sciences, Vanderbilt University, School of Medicine, Nashville, TN 37232, USA.
Hear Res. 2024 Jul;448:109020. doi: 10.1016/j.heares.2024.109020. Epub 2024 Apr 28.
Combining cochlear implants with binaural acoustic hearing via preserved hearing in the implanted ear(s) is commonly referred to as combined electric and acoustic stimulation (EAS). EAS fittings can provide patients with significant benefit for speech recognition in complex noise, perceived listening difficulty, and horizontal-plane localization as compared to traditional bimodal hearing conditions with contralateral and monaural acoustic hearing. However, EAS benefit varies across patients and the degree of benefit is not reliably related to the underlying audiogram. Previous research has indicated that EAS benefit for speech recognition in complex listening scenarios and localization is significantly correlated with the patients' binaural cue sensitivity, namely interaural time differences (ITD). In the context of pure tones, interaural phase differences (IPD) and ITD can be understood as two perspectives on the same phenomenon. Through simple mathematical conversion, one can be transformed into the other, illustrating their inherent interrelation for spatial hearing abilities. However, assessing binaural cue sensitivity is not part of a clinical assessment battery as psychophysical tasks are time consuming, require training to achieve performance asymptote, and specialized programming and software all of which render this clinically unfeasible. In this study, we investigated the possibility of using an objective measure of binaural cue sensitivity by the acoustic change complex (ACC) via imposition of an IPD of varying degrees at stimulus midpoint. Ten adult listeners with normal hearing were assessed on tasks of behavioral and objective binaural cue sensitivity for carrier frequencies of 250 and 1000 Hz. Results suggest that 1) ACC amplitude increases with IPD; 2) ACC-based IPD sensitivity for 250 Hz is significantly correlated with behavioral ITD sensitivity; 3) Participants were more sensitive to IPDs at 250 Hz as compared to 1000 Hz. Thus, this objective measure of IPD sensitivity may hold clinical application for pre- and post-operative assessment for individuals meeting candidacy indications for cochlear implantation with low-frequency acoustic hearing preservation as this relatively quick and objective measure may provide clinicians with information identifying patients most likely to derive benefit from EAS technology.
将人工耳蜗与保留植入耳听力的双耳声学听觉相结合通常被称为联合电声刺激（EAS）。与传统的对侧和单耳声学听觉的双模听觉条件相比，EAS 适配可以为患者在复杂噪声中的言语识别、感知听力困难和水平定位提供显著的益处。然而，EAS 的益处因人而异，而且受益程度与潜在的听力图没有可靠的关系。以前的研究表明，EAS 对复杂听力环境中的言语识别和定位的益处与患者的双耳线索敏感性（即，耳间时间差（ITD））显著相关。在纯音的情况下，耳间相位差（IPD）和 ITD 可以被理解为同一现象的两个视角。通过简单的数学转换，一个可以转换为另一个，说明它们对空间听觉能力的内在关系。然而，评估双耳线索敏感性并不是临床评估电池的一部分，因为心理物理任务耗时、需要训练才能达到性能渐近线，并且需要专门的编程和软件，所有这些都使这在临床上不可行。在这项研究中，我们通过在刺激中点施加不同程度的 IPD 来研究使用声变复合（ACC）作为客观双耳线索敏感性测量的可能性。10 名听力正常的成年受试者接受了 250Hz 和 1000Hz 载波频率的行为和客观双耳线索敏感性任务评估。结果表明：1）ACC 幅度随 IPD 增加；2）基于 ACC 的 250Hz IPD 敏感性与行为 ITD 敏感性显著相关；3）与 1000Hz 相比，参与者对 250Hz 的 IPD 更敏感。因此，这种 IPD 敏感性的客观测量可能对符合低频声学听力保留的人工耳蜗植入候选者的术前和术后评估具有临床应用价值，因为这种相对快速和客观的测量方法可以为临床医生提供信息，识别最有可能从 EAS 技术中受益的患者。
