Auditory spatial discrimination measures, including interaural time difference (ITD), interaural level difference (ILD), minimum audible angle (MAA) and bisection accuracy (BA), are key components of spatial auditory processing and contribute to accurate sound localization. Age-related declines in these abilities can negatively impact spatial awareness and daily communication. The study investigated the sensitivity of four spatial hearing measures— ITD, ILD, MAA and BA to age-related changes in auditory spatial discrimination. An experimental cross-sectional study design was adopted, with purposive sampling of 44 clinically normal-hearing participants (22 young and 22 middle-aged adults). Spatialized white noise bursts were generated by convolving signals with non-individualized head-related transfer functions using the 3D Tune-In Toolkit, a software environment for simulating 3D audio over headphones. ITD and ILD tasks involved detecting time and intensity differences between ears. MAA assessed the smallest discriminable angle. BA measured the ability to bisect auditory space into two hemifields. MANOVA revealed significant main effect of age across all measures (p < 0.001), with middle-aged adults showing significantly poorer spatial discrimination. Receiver Operating Characteristic analyses identified MAA as the most sensitive measure. Fisher's Discriminant analysis further validated the discriminatory power of MAA for group categorization. These findings suggest that auditory spatial discrimination abilities may begin to show subtle changes at mid-adulthood. The MAA shows to be a promising marker out of the four measures for detecting early spatial processing deficits.
Mali et al. (Tue,) studied this question.