An Encepholographic Investigation of Spatial Cue Augmentation

人类听觉系统的空间定位能力是我们听觉感知的一个基本方面。这种能力不仅有助于在三维空间中定位声源，而且还能够在复杂的声音场景中选择性地注意特定的声源，这种现象通常被称为“鸡尾酒会效应”。其关键是用于水平定位的两耳间时间和电平差异（IT和ILD），以及用于仰角和模糊声源位置的单耳频谱线索。这些线索是高度个性化的，仅由每个听者的独特形态决定。因此，非个性化的线索可能会对空间感知产生不利影响。不能保留这些线索的助听器会损害听力受损（HI）个体的空间感知。虽然双耳线索保留可以提高语音清晰度和定位，但HI听众仍可能面临由于频率特定性听力损失而带来的挑战。适应非个人空间线索已被证明，阿姆斯特朗等人。的研究结果表明，个人的HRTF测量可能不是最好的空间感知的所有方面，这表明需要应用特定的HRTF选择。这些发现不仅强调了量身定制的空间线索的重要性，但也提出了一个问题，是否可以增加空间线索，以提高特定的行为方面的空间perception.Spatial听力评估传统上依赖于两个主要的方法：数字的措施，如频谱失真和更先进的听觉模型，以及主观的听力测试，如定位测试。然而，这两种方法都有缺点。数值指标可能会错过感知的细微差别，主观测试可能会被个人的辨别能力所扭曲。因此，需要更客观的空间感知测量。脑电图（EEG）提供了希望。脑电图是一种非侵入性的方法，用于记录大脑活动，提供对听觉感知的潜在神经机制和途径的见解。EEG可以检测事件相关电位（ERP），它在听觉空间知觉的背景下，可以提供有价值的洞察大脑如何处理和整合空间线索的时间动态。机器学习（ML）的进步增强了对EEG数据的解释，可能为助听器和消费电子产品等设备的空间感知动态评估提供信息。相关空间线索的重要性，听者适应非个体线索的能力，空间线索增强和基于EEG的空间听觉效能评估方法的前景激发了本博士学位的目标，包括（1）探索改变的空间线索对空间听觉和言语可懂度的行为影响，（2）设计增强空间线索的方法以增强空间感知的特定方面，以及（3）评估空间线索增强的神经相关性。

The human auditory system's spatial localisation capability is a fundamental aspect of our auditory perception. This ability not only facilitates the localisation of sound sources in three-dimensional space but also enables selective attention to specific sound sources in complex sound scenes, a phenomenon popularly termed the 'cocktail party effect'. Key to this are interaural time and level differences (IT and ILD) for horizontal localization, and monaural spectral cues for elevation and ambiguous source locations.These cues are highly individual, determined solely by each listener's unique morphology. Consequently, non-individualised cues can adversely impact spatial perception. Hearing aids that fail to preserve these cues can impair spatial perception in hearing-impaired (HI) individuals. While binaural cue preservation can enhance speech intelligibility and localization, HI listeners may still face challenges due to frequency-specific hearing loss. Adaptation to non-individual spatial cues has been shown, and Armstrong et al.'s findings suggest that individual HRTF measurements may not be the best for all aspects of spatial perception, indicating the need for application-specific HRTF selection. These findings not only underscore the importance of tailored spatial cues but also pose the question of whether spatial cues can be augmented to enhance specific behavioural aspects of spatial perception.Spatial hearing assessment traditionally relies on two main methods: numerical measures like spectral distortion and more advanced auditory models, as well as subjective listening tests such as localisation tests. However, both approaches have drawbacks. Numerical metrics may miss perceptual nuances, and subjective tests can be skewed by individual discernment abilities. Thus, there is a need for more objective measures of spatial perception. Electroencephalography (EEG) offers promise. EEG is a non-invasive method for recording brain activity, providing insights into the underlying neural mechanisms and pathways of auditory perception. EEG can detect event-related potentials (ERPs), which in the context of auditory spatial perception, canprovide valuable insights into the temporal dynamics of how the brain processes and integrates spatial cues. Advances in machine learning (ML) enhance the interpretation of EEG data, potentially informing the dynamic assessment of spatial perception in devices like hearing aids and consumer electronics.The importance of pertinent spatial cues, listener ability to adapt to non-individual cues, the promise of spatial cue augmentation and EEG-based evaluation methods of spatial hearing efficacy motivate the aims of this PhD comprising (1) Exploring the behavioural impact of altered spatial cues on spatial hearing and speech intelligibility, (2) Designing methods to augment spatial cues to enhance specific aspects of spatial perception and (3) Evaluating the neural correlates of spatial cue augmentation.