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处理来支持的。优先效应或“第一波前定律”就是这样的双耳心理声学效应。当一个声音之后是另一个声音，间隔了足够短的时间延迟(低于听者的回声阈值)，听者感知到一个单一的融合听觉图像；其感知的空间位置由第一个到达的声音(第一个波前，Wallach等人)的位置主导。1949年)。对于双侧植入人工耳蜗(CI)的使用者来说，不会发生这种听觉事件的融合，并且要么存在两种空间分离的感知，要么直接声音(Lead)的定位受到反射(Lag)的干扰(Seeber&HAfter 2008)。为了解释联合电声刺激(EAS)和双侧声低频残余听力的使用者所观察到的听力改善，我们怀疑感知是由优先效应支持的。然而，EAS设备的声学和电学组件之间的现有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调查EAS用户中的双耳交互作用，并结合“同步”声刺激。以前的实验设置(BA 2085/3-1)仅允许对EAS用户和传统CI用户在日常生活中的语音感知得出有限的结论。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EAS使用者的耳间电平阈值和延迟差异。结果将与其他受试者组(双侧人工耳蜗组、单侧耳聋CI组和非对称性内耳听力损失组)进行比较。在初步实验中，将分别测定和补偿装置的电和声学部分之间的延迟时间。通过我们实验室安装的多通道声音再现系统(128个扬声器)，通过波场合成的方法产生复杂的声场，以研究日常环境中人工耳蜗和混合植入物的双耳效应。更好地了解EAS效应将有助于开发人工耳蜗系统的优化匹配策略，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.