An Encepholographic Investigation of Spatial Cue Augmentation

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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.