Four Decades of Change in the Acoustic Profile of Japanese Hit Songs (1980–2025)

Music is often described as mirroring the socio-cultural landscape of its time. However, the long-term acoustic evolution of hit songs in non-Western contexts remains underexplored. This study investigated the temporal changes in loudness, spectral flux, and groove-related acoustic features of 360 Japanese hit songs released between 1980 and 2025. Acoustic descriptors were extracted using MIRtoolbox, including RMS, loudness units relative to full scale (LUFS), dynamic range, full-band and sub-band spectral flux, pulse clarity, percussiveness, event density, tempo, brightness, roughness, and mode. Regression analyses revealed a substantial long-term increase in overall loudness (RMS and LUFS), consistent with the so-called “loudness war” in the Western context. Spectral flux increased, particularly in low-frequency sub-bands; however, the salience of the change was lower than that reported in Western datasets. Event density, roughness, and major mode tendencies increased significantly over the years. By contrast, percussiveness and pulse clarity did not exhibit any systematic changes. These findings suggest that Japanese hit songs have progressively incorporated certain embodiment- and groove-related characteristics, similar to those found in Western hit charts; however, not all groove-related elements have increased uniformly. Taken together, hit songs appear to retain region-specific characteristics while simultaneously exhibiting convergent acoustic trends across cultures over time.