Virtual Reality has emerged as a promising medium for high-stakes training, yet its predominantly visual design places disproportionate demands on attentional resources, limiting capacity for other task-relevant information. Spatial audio cues exploit the underutilized auditory channel to redistribute this load, with demonstrated improvements in reaction time, search efficiency, and situational awareness. However, when audio cues are spatially incongruent with visual targets, task performance degrades. The cognitive and behavioral costs of such incongruency, particularly under increasing visual complexity, remain underexplored. This pilot study examines how audiovisual spatial incongruency affects mental workload and task performance through a within-subjects VR experiment in which 15 participants complete a search-and-respond task across congruent and incongruent audiovisual conditions at three levels of visual complexity. Reaction time, target accuracy, timeouts, and subjective workload are measured across 10 trials per participant. Audiovisual incongruency is hypothesized to increase mental workload and impair performance, with effects amplified under higher visual complexity. Findings will inform spatial audio design for immersive training systems and motivate further investigation into tolerance thresholds for audiovisual misalignment.
