Auditory selective attention in depth: Investigating directional dependency across front, lateral, and rear spaces

Auditory spatial attention enables listeners in complex acoustic environments to focus on relevant sounds while filtering out irrelevant noise. However, its mechanisms in the depth dimension remain unclear, especially across different horizontal directions. This study examined whether the effect of auditory selective attention in the depth dimension varies across the front, lateral, and rear spaces under reverberant listening conditions. In the experiment, listeners detected target sounds at one of five distances (32, 64, 96, 128, and 160 cm) under conditions where attention was either distributed or focused on a specific distance. The results showed that sensitivity (d') was significantly enhanced at the attended distance across all directional conditions, with no statistically significant differences in the magnitude of attentional enhancement between the front, lateral, and rear directions. Conversely, the reaction time (RT) revealed limited attentional benefits, emerging only at specific distances in the lateral and rear spaces. These findings demonstrated that auditory selective attention in the depth dimension facilitates target detection irrespective of horizontal directions, supporting the generalizability of attentional mechanisms across the depth dimension of auditory space, at least under reverberant listening conditions.