Auditory-Olfactory Integration in Simulated Natural Environments Dissociates Neural and Subjective Responses in...

Visually impaired individuals rely on cross-modal plasticity to compensate for absent visual input, yet the neurophysiological mechanisms underlying naturalistic auditory-olfactory integration remain poorly characterized. This study investigated how combined auditory and olfactory cues in representative landscape scenarios modulate cortical activity and multidimensional perceptual experience in 20 visually impaired participants. Five ecologically distinct scenarios-wooded resting areas, dynamic water features, aromatic planting beds, open lawns, and hard-paved plazas-were simulated using synchronized playback of field-recorded soundscapes and calibrated odor diffusion systems. Participants completed standardized ratings across auditory, olfactory, and integrated perceptual dimensions while electroencephalographic (EEG) recordings were acquired. Occipital α/β ratios (O1/O2) served as the primary neurophysiological index of cortical relaxation. Results demonstrated a dissociation between explicit hedonic appraisal and implicit neurophysiological response: dynamic water soundscapes dominated subjective preference ratings, whereas floral olfactory cues in low-amplitude acoustic contexts elicited the highest α/β ratios, significantly exceeding those recorded in wooded and open lawn scenarios. Odor familiarity correlated inversely with α/β elevation (r = -0.46, p < 0.05), indicating that unfamiliar floral scents triggered more robust relaxation responses than familiar urban olfactory environments. This correlation may reflect novelty-related attentional processes rather than relaxation per se. Exploratory clustering revealed stable, trait-like individual differences in baseline α/β activity that were not explained by perceptual ratings, and linear mixed-effects modeling confirmed that inter-individual baseline differences, rather than linear coupling with conscious evaluations, drove α/β variance. Given the relatively small sample size, these findings should be regarded as preliminary and hypothesis-generating. Nevertheless, they extend current models of cross-modal neuroplasticity by demonstrating that naturalistic multisensory integration follows dissociable subjective and neurophysiological trajectories, informing evidence-based multisensory interventions for accessible environmental design.