The influence of postural load and early aging on dynamic sound localization: Evidence for reduced cognitive-motor reserve.

This study investigated the effects of head movements and postural stability on sound localization performance in normal-hearing adults and explored age-related differences between individuals aged 20-30 and 30-40 years. A total of 102 participants were divided into two groups: Group 1 (n = 56, 20-30 years) and Group 2 (n = 46, 30-40 years). Using a virtual reality system, localization performance was assessed under three different postural conditions and two listening conditions (head-immobile and head-mobile). Localization errors were measured at a 55-cm distance across four azimuth angles (right-front, left-front, right-back, left-back). Primary outcome measures included Azimuth Error, Front-Back Confusions, and Overall 3D Error. Incorporating head movements resulted in a statistically significant improvement in localization performance across all surface conditions (p < .001). In the head-mobile condition, the sitting posture yielded significantly lower Front 3D Error compared to both firm (p = .005) and foam surfaces (p = .007). Age-related differences were found to influence localization performance across varying levels of postural stability. Group 2 demonstrated significantly higher localization errors than Group 1 in the sitting condition (e.g., Head-Immobile Overall 3D Error: p = .021) and on the foam surface (e.g., Head-Immobile Overall 3D Error: p = .046). Conversely, no significant differences were found between the groups for any parameter on the firm surface. These findings indicate that head movements substantially enhance spatial hearing accuracy. However, localization performance is modulated by postural stability and age. Increased postural challenge appears to impose a dual-task cost, revealing subtle early age-related changes in the cognitive-motor mechanisms underlying auditory-spatial integration.