Neural Mechanisms of Binaural Hearing

描述（由申请人提供）：在三维空间中定位声音需要处理方位角、仰角和距离。虽然相当多的注意力集中在方位和海拔线索的神经处理，我们的知识的神经处理的距离几乎是不存在的。心理物理学和建模研究表明，混响环境中的距离感知是基于混响与直达声能量的比值。该比率随着距离而变化，因为距离加倍时，直达能量以每6dB减小，但是混响能量随着距离保持大致恒定。距离的另一个提示是随着距离的减小，双耳水平差增加。另一个潜在的线索是高频能量随着距离的增加而系统性地减少。为了研究声音距离的神经处理，我们将使用从耳道录音中产生的虚拟声音，以从我们最先进的消声室和混响室中产生的不同距离和方位发出的声音。在人类听众中，这种虚拟声音产生适当外部化和局部化的听觉图像。我们将使用这种虚拟技术，因为与在真实的声场中进行神经记录相比，它允许对听觉线索进行解剖和修改，并且在采样空间位置时提供更高的效率和灵活性。它还允许在从神经元记录的同时，从无回声环境到混响环境来回切换。我们将探讨在消声和混响环境中的距离处理，因为声学是完全不同的，这两种环境，在某种程度上，通常是人类和其他动物所经历的。本实验旨在研究无回声和混响环境下，家兔下丘神经元对声源距离的神经编码。具体来说，我们将研究距离和方位角，距离和声环境，方位角和声环境之间的神经相互作用的效果。这些结果可能有助于设计助听器，人工耳蜗植入物和机器人设备，以整合空间听觉的所有3个维度。

DESCRIPTION (provided by applicant): Localizing a sound in 3-dimensional space requires the processing of azimuth, elevation, and distance. Although considerable attention has been focused on the neural processing of azimuthal and elevational cues, our knowledge of the neural processing of distance is almost non-existent. Psychophysical and modeling studies show distance perception in reverberant environments is based on the ratio of reverberant to direct sound energy. This ratio changes with distance because the direct energy decreases at 6 dB per for doubling of distance, but reverberant energy remains about constant with distance. Another cue for distance are the increases in interaural level difference with decreasing distance. Another potential cue is the systematic decrease in high frequency energy with increasing distance. To investigate the neural processing of sound distance, we will use virtual sounds made from ear canal recordings to sounds emanating from different distances and azimuths that are made in our state-of-the-art anechoic and reverberant chambers. In human listeners, such virtual sounds produce auditory images that are appropriately externalized and localized. We will use this virtual technology because, in comparison to making neural recordings in the real sound field, it allows the dissection and modification of auditory cues and also offers far greater efficiency and flexibility in sampling spatial locations. It also permits switching back and forth from the anechoic to reverberant environment, while recording from a neuron. We will explore distance processing in both anechoic and reverberant environments because the acoustics are quite different and both of these environments, to one degree or another, are normally experienced by humans and other animals. Our aim is to determine the neural coding of sound source distance in anechoic and reverberant environment in neurons of the inferior colliculus in the unanesthetized rabbit. Specifically, we will examine the effect of neural interactions between distance and azimuth, distance and acoustic environment, and azimuth and acoustic environment. The results may be helpful in designing hearing aids, cochlear implants, and robotic devices to incorporate all 3 dimensions of spatial hearing.