Binaural hearing supports effective communication in complex acoustic environments by enabling listeners to segregate spatially separated sound sources, a benefit referred to as spatial release from masking (SRM). The spatial cues that give rise to SRM are determined by the head-related transfer function (HRTF). Although individual HRTFs are generally considered optimal for accurate localisation, prior work suggests they do not necessarily maximise performance across all aspects of spatial perception, including SRM. This motivates the concept of application-specific HRTFs. Here, we propose an application-specific HRTF augmentation method to improve speech intelligibility in cocktail-party scenarios, focusing on front–back configurations where SRM is limited. HRTFs are parameterised using principal component analysis and optimised via a differentiable auditory-model-based objective to enhance spectral cues while constraining interaural level differences. The method yields model-predicted SRM gains of 4–9 dB without inducing substantial predicted lateralisation artefacts.
