Peter Osypka Institute of Medical Engineering, Faculty of Electrical Engineering, Medical Engineering and Computer Sciences, University of Applied Sciences Offenburg, Germany.
Bio-Inspired Information Processing, Munich School of Bioengineering, Technical of University Munich, Germany.
Trends Hear. 2021 Jan-Dec;25:23312165211016165. doi: 10.1177/23312165211016165.
Users of a cochlear implant (CI) in one ear, who are provided with a hearing aid (HA) in the contralateral ear, so-called bimodal listeners, are typically affected by a constant and relatively large interaural time delay offset due to differences in signal processing and differences in stimulation. For HA stimulation, the cochlear travelling wave delay is added to the processing delay, while for CI stimulation, the auditory nerve fibers are stimulated directly. In case of MED-EL CI systems in combination with different HA types, the CI stimulation precedes the acoustic HA stimulation by 3 to 10 ms. A self-designed, battery-powered, portable, and programmable delay line was applied to the CI to reduce the device delay mismatch in nine bimodal listeners. We used an A-B-B-A test design and determined if sound source localization improves when the device delay mismatch is reduced by delaying the CI stimulation by the HA processing delay (τ). Results revealed that every subject in our group of nine bimodal listeners benefited from the approach. The root-mean-square error of sound localization improved significantly from 52.6° to 37.9°. The signed bias also improved significantly from 25.2° to 10.5°, with positive values indicating a bias toward the CI. Furthermore, two other delay values (τ -1 ms and τ +1 ms) were applied, and with the latter value, the signed bias was further reduced in some test subjects. We conclude that sound source localization accuracy in bimodal listeners improves instantaneously and sustainably when the device delay mismatch is reduced.
使用一只耳朵中的人工耳蜗（CI），并在对侧耳朵中提供助听器（HA）的使用者，即所谓的双模聆听者，通常会受到由于信号处理差异和刺激差异导致的恒定且相对较大的耳间时间延迟偏移的影响。对于 HA 刺激，耳蜗行波延迟会被添加到处理延迟中，而对于 CI 刺激，听觉神经纤维会直接被刺激。对于 MED-EL CI 系统与不同类型的 HA 结合使用的情况，CI 刺激会比声学 HA 刺激提前 3 到 10 毫秒。我们应用了一个自行设计的、电池供电的、便携式和可编程的延迟线，以减少九名双模聆听者中 CI 设备的延迟不匹配。我们使用 A-B-B-A 测试设计，确定通过将 CI 刺激延迟 HA 处理延迟（τ）来减少设备延迟不匹配是否可以改善声源定位。结果表明，我们的九名双模聆听者组中的每个受试者都受益于该方法。声源定位的均方根误差从 52.6°显著改善至 37.9°。有符号偏差也从 25.2°显著改善至 10.5°，正值表示偏向 CI。此外，还应用了另外两个延迟值（τ-1ms 和 τ+1ms），并且在后一个值下，一些测试对象的有符号偏差进一步减小。我们得出结论，当减少设备延迟不匹配时，双模聆听者的声源定位准确性可以即时和持续地提高。
