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，在混响环境下的言语感知要困难得多，而在这种情况下，正常的听力是通过双耳加工来支持的。优先效应或“第一波前定律”就是这样一种双耳心理声学效应。当一个声音之后是另一个声音，间隔足够短的时间延迟（低于听者的回声阈值），听者感知到一个单一的融合的听觉图像；其感知到的空间位置主要由第一个到达的声音的位置决定（第一波阵面，Wallach et al. 1949）。对于双侧植入人工耳蜗（CI）的使用者来说，不会发生这样的听觉事件融合，要么存在两个空间分离的感知，要么直接声音的定位（导音）受到反射（滞后）的干扰（Seeber & Hafter 2008）。为了解释在双侧低频残余听力的电声联合刺激（EAS）使用者中观察到的听力改善，我们怀疑感知是由优先效应支持的。然而，现有的声电元件之间的延迟可能会阻碍优先效应的利用。因此，该项目的核心目标是结合“同步”声刺激研究EAS用户的双耳相互作用。先前的实验设置（BA 2085/3-1）只允许对日常生活中EAS和传统CI用户的语音感知得出有限的结论。特别是，由于电/电声联合刺激缺乏优先效应而导致的恶化程度尚未确定。作为BA 2085/3-1项目继续进行的一部分，心理声学听力测试应评估一组easa用户的耳间水平和延迟差异的阈值。结果将与其他受试者组（双侧人工耳蜗、单侧耳聋（SSD） CI组和不对称内耳听力损失组）进行比较。在初步实验中，将分别确定和补偿器件的电和声元件之间的延迟时间。通过安装在实验室的多声道声音再现系统（128个扬声器），以波场合成的方式产生复杂的声场，以研究人工耳蜗和混合植入物在日常环境中的双耳效应。更好地了解EAS效应将有助于开发优化的人工耳蜗系统适配策略，从而提高复杂听力情况下的语音理解能力。

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.