Investigation of binaural hearing with bilateral/hybrid-bilateral cochlear implant in simulated room and noise conditions

对于听力受损的人来说，在混响环境中的语音感知要困难得多，而在这种情况下，通过双耳处理来支持正常的听力。优先效应或“第一波阵面定律”就是这样一种双耳心理声学效应。当一个声音后面跟着另一个声音，而另一个声音之间相隔足够短的时间延迟（低于听者的回声阈值）时，听者会感知到一个融合的听觉图像;其感知的空间位置由第一个到达的声音的位置主导（第一波阵面，Wallach等人，1949）。对于双侧植入的人工耳蜗（CI）用户，没有发生这种听觉事件的融合，并且存在两个空间分离的感知，或者直接声音（导联）的定位受到反射（滞后）的干扰（Seeber & Hafter 2008）。为了解释在使用电声联合刺激（EAS）和双侧声学低频残余听力的用户中观察到的听力性能改善，我们怀疑感知受到优先效应的支持。然而，EAS设备的声学和电气部件之间的现有延迟可能妨碍优先效应的利用。因此，该项目的核心目标是调查双耳互动EAS用户结合“同步”acoustics.Previous实验设置（BA 2085/3-1）只允许有限的结论EAS和传统CI用户在日常生活中的语音感知。特别是，由于缺乏电/组合电声刺激的优先效应而导致的恶化程度尚未确定。作为项目BA 2085/3-1的延续的一部分，心理声学听力测试应评估一组EAS用户的耳间水平和延迟差异的阈值。将结果与其他受试者组（双侧人工耳蜗植入、单侧耳聋（SSD）CI和不对称内耳听力损失组）进行比较。在初步实验中，将单独确定和补偿设备的电气和声学部件之间的延迟时间。（128个扬声器）安装在我们的实验室，为了研究人工耳蜗和混合式人工耳蜗在日常环境中的双耳效应，通过波场合成的方法产生了复杂的声场。导致开发用于耳蜗植入系统的优化适配策略，从而可以实现在复杂收听情况下的语音理解的改善。

For hearing-impaired people speech perception in environments with reverberation is much more difficult, while normal hearing is supported in such situations by binaural processing. The precedence effect or the 'law of the first wavefront' is such a binaural psychoacoustic effect. When a sound is followed by another sound separated by a sufficiently short time delay (below the listener's echo threshold), listeners perceive a single fused auditory image; its perceived spatial location is dominated by the location of the first-arriving sound (the first wave front, Wallach et al. 1949). For bilaterally implanted cochlear implant (CI) users occurs no such fusion of auditory events and there are either two spatially separated perceptions or the localization of direct sound (lead) is disturbed by reflections (lag) (Seeber & Hafter 2008). To explain the improved hearing performance observed in users of combined electric-acoustic stimulation (EAS) with bilateral acoustic low frequency residual hearing, we suspect that perception is supported by the precedence effect. However, the existing delay between acoustic and electrical components of the EAS devices could hamper the utilization of the precedence effect. Core objective of the project is therefore the investigation of binaural interactions in EAS users in combination with "synchronized" acoustic stimulation.Previous experimental setups (BA 2085/3-1) allowed only limited conclusions about speech perception of EAS and conventional CI users in everyday life. In particular, the extent of the deterioration resulting from the lack of the precedence effect in electrical / combined electric-acoustic stimulation was not determined.As part of the continuation of the project BA 2085/3-1, psychoacoustic listening tests shall assess the threshold of interaural level and delay differences in a group of EAS-users. Results will be compared with other groups of subjects (bilateral cochlear implant, CI in single-sided deafness (SSD), and a group consisting of asymmetrical inner ear hearing loss). In preliminary experiments, the delay time between the electric and acoustic components of the devices will be individually determined and compensated.Through the multichannel sound reproduction system (128 speakers) installed in our laboratory, complex sound fields are generated by means of wave field synthesis in order to investigate binaural effects with cochlear and hybrid implants in everyday environments.A better understanding of the EAS effect will lead to the development of optimized fitting strategies for cochlear implant systems, so that improvement in speech understanding in complex listening situations can be achieved.