Exploratory study on in-cabin soundscapes: Psycho-physiological responses and user experience in music listening environments

This exploratory study evaluates audio-rendering method and listening position in-cabin music listening environments under controlled audiovisual presentation. Twenty-two participants experienced two, 6 min music excerpts under five scenarios combining reference stereo playback, measured impulse-response–based seat-specific auralization, and surround-enhanced Dolby 5.1 reproduction. Perceptual ratings consistently differentiated the scenarios. Surround-enhanced conditions generally improved spatial impression, envelopment, and presence/realism relative to the standard auralized conditions, while front and rear listening positions produced different clarity and reverberance patterns consistent with measured impulse-response differences. Heart rate variability showed a significant omnibus effect for the low-frequency/high-frequency ratio in the orchestra excerpt, although corrected pairwise differences were not robust; electroencephalography alpha power showed condition-dependent regional differences in temporal, parietal, and occipital areas. Correlation analyses linked level and psychoacoustic descriptors, including sharpness and dynamic level range, to perceptual attributes, indoor soundscape expressions, and overall impression. The study contributes a reproducible measurement-based workflow for seat-aware in-cabin music soundscape evaluation and suggests that passenger audio tuning should consider rendering method and listening position as coupled design variables.