The impact of individual head-related transfer function augmentation on spatial release from masking

Binaural hearing underpins effective communication in complex acoustic environments by increasing listeners' abilities to segregate concurrent sound sources. In certain conditions, interaural magnification of binaural cues has been shown to improve speech intelligibility in competing target masker scenarios, yet existing methods primarily comprise hearing aid algorithms, which, due to processing constraints, cause unwanted artefacts. Moreover, the perceptual effects of applying interaural magnification directly to a person's own head-related transfer function (HRTF) remain unclear. We revisit a previous method for magnifying interaural cues, apply it to individual HRTFs, and propose a modified version designed to reduce spatial distortions. We evaluate both approaches using auditory models and listening tests involving speech-on-speech masking with a midline target and symmetrical maskers. Behavioural results show that although magnifying interaural phase and level differences improves overall speech intelligibility compared to unmodified HRTFs, it does not significantly enhance spatial release from masking (SRM). Meanwhile, auditory model predictions suggest greater SRM gains than those observed behaviourally, suggesting an influence of listener familiarity with their individual spatial cues. Finally, interaural magnification benefits diminish for listeners who already exhibit strong SRM with their own HRTFs.