Behavioral and Physiological Effects of Binaural Cue Distortion

描述(由申请者提供)：在空间中定位和隔离声源的能力对于交流和环境意识非常重要。听力正常(NH)的人类听者根据耳间时间和声级差(ITD和ILD)--声源方位的双耳声学提示--有效地定位和隔离声源。使用助听器(HAS)和人工耳蜗(CI)的听障人士，其识别这些线索的能力往往显著或严重受损，导致日常听力环境中的严重沟通困难。这些缺陷被认为是患者因素的组合造成的，例如长时间的听觉剥夺导致中央功能改变，以及临床设备的限制，例如信号处理的时间精度不高或自动增益控制算法的双边不对称。改善对双耳听力表现的信号相关限制的了解将导致对双耳系统的基本了解的增强，并可能导致临床设备技术和患者结果的改善。因此，这项研究的长期目标是阐明双耳线索退化对声音局部化和分离的影响，从而改善对正常和受损双耳听力的理解。本研究的具体目的是：(1)表征耳间去相关和时变ILD压缩对正常听觉对ILD、ITD和虚拟声源位置的心理物理敏感性的影响；(2)表征这种失真对ILD、ITD和虚拟声源方位编码的影响。实验将结合(1)行为任务，包括辨别、颅内定侧和虚拟空间定位，以表征对控制和双耳退化刺激的心理物理敏感性，包括我们最近测量的实际双侧HA输出产生的模拟“设备处理”刺激，以及(2)用于表征生理(神经)对控制和退化刺激敏感性的活体细胞外记录技术。行为和神经数据将使用Fisher信息进行关联，以比较行为和神经双耳的辨别性能。在这些实验的同时，申请者将定期与临床医生(包括共同赞助者)会面，并观察临床会议，以获得关于听力损失患者面临的沟通和其他听力困难的更多视角。这样的会议将丰富申请者的培训，并可能为未来实验的后续设计提供见解。拟议的工作将通过促进对双耳听觉系统的基本了解和对双边临床设备(特别是HAS)对双耳益处的外部(与信号相关的)限制来支持NIDCD的使命。

DESCRIPTION (provided by applicant): The ability to localize and segregate sound sources in space is important for communication and environmental awareness. Normal-hearing (NH) human listeners effectively localize and segregate sound sources on the basis of interaural time and level differences (ITD and ILD) - binaural acoustic cues to sound source azimuth. Hearing-impaired individuals who use hearing aids (HAs) and cochlear implants (CIs) are often significantly or profoundly impaired in their abilities to detect these cues, leading to significan communication difficulties in everyday listening environments. Such deficits are believed to arise from a combination of patient factors, such as prolonged auditory deprivation leading to altered central function, and clinical device limitations, such as inadequate temporal precision in signal processing or bilateral asymmetry in automatic gain control algorithms. An improved understanding of signal-related limitations on binaural hearing performance will lead to an enhanced basic understanding of the binaural system and may lead to consequent improvements in clinical device technology and patient outcomes. Therefore, the broad long-term goal of the proposed research is to elucidate the effects of binaural cue degradations on sound localization and segregation, toward improved understanding of normal and impaired binaural hearing. The specific aims of the proposed research are: (1) To characterize the effects of interaural decorrelation and time-varying ILD compression on normal-hearing psychophysical sensitivity to ILD, ITD and virtual sound source location and (2) to characterize the effects of such distortions on the encoding of ILD, ITD and virtual sound source azimuth by neurons of the inferior colliculus. Experiments will integrate (1) behavioral tasks including discrimination, intracranial lateralization, and virtual space localization for characterization of psychophysical sensitivity to control and binaurally degraded stimuli, including simulated "device-processed" stimuli generated from our recent measurements of actual bilateral HA outputs and (2) in vivo extracellular recording techniques for characterization of physiological (neural) sensitivity to control and degraded stimuli. Behavioral and neural data will be related using Fisher information to compare behavioral and neural binaural discrimination performance. Simultaneous with these experiments, the Applicant will regularly meet with clinicians (including the Co- Sponsor) and observe clinical sessions to gain additional perspective on communicative and other listening difficulties faced by people with hearing loss. Such meetings will enrich the Applicant's training and may provide insights for the design of follow-up of future experiments. The proposed work will support the mission of NIDCD by advancing basic understanding of the binaural auditory system and exogenous (signal-related) limitations on binaural benefit from bilateral clinical devices (especially HAs).