Influences of Nonlinear Distortion in Music Playback on Listeners’ Stress Evaluated by PPI and RMSSD of PPG

Nakada K, Muramatsu S, Yoshida T. Influences of Nonlinear Distortion in Music Playback on Listeners’ Stress Evaluated by PPI and RMSSD of PPG. In: Express Paper. Audio Engineering Society; 2026.pp. 437:1-. Available from: https://aes.org/publications/elibrary-page/?id=23162

@inproceedings{Nakada2026_23162,
  author = {Nakada, Kenshin and Muramatsu, Shun and Yoshida, Takahiro},
  title = {{Influences of Nonlinear Distortion in Music Playback on Listeners’ Stress Evaluated by PPI and RMSSD of PPG}},
  pages = {437:1-},
  year = {2026},
  month = may,
  publisher = {Audio Engineering Society},
  url = {}
}

TY  - CPAPER
TI  - Influences of Nonlinear Distortion in Music Playback on Listeners’ Stress Evaluated by PPI and RMSSD of PPG
AU  - Nakada, Kenshin
AU  - Muramatsu, Shun
AU  - Yoshida, Takahiro
SP  - 1
M1  - Paper 437
PY  - 2026
DA  - 2026/05/28
UR  - https://aes.org/publications/elibrary-page/?id=23162
PB  - Audio Engineering Society
LA  - en
AB  - The phenomenon in which listeners impressions of music are unintentionally altered even when the same sound source is played back remains an important issue. Previous research has shown that the state and combination of audio equipment affect the characteristics of nonlinear distortion in music playback. Hence, we conducted subjective evaluations of auditory and musical impressions using sound sources with various nonlinear distortions. However, the subjective evaluation was unstable and difficult to assess. The reason was that the sound change was perceived emotionally as a slight change in sound image and musicality, and that interpretation of evaluation terms varied widely among subjects due to the difficulty of verbalizing the impression. Therefore, we evaluated the change in listeners stress caused by nonlinear distortion in music playback using photoplethysmography (PPG). In this study, we conducted a follow-up experiment with improved accuracy. In the experiment, 41 subjects listened to sound sources with even-order / odd-order harmonic distortions and no distortion. The musical piece of sound sources is an original to eliminate familiarity and bias toward existing music. We evaluated changes in subjects stress states using the mean pulse-pulse interval (PPI) and the root mean square of successive differences (RMSSD), computed from the PPG signal, as indicators of stress. These results reconfirm that nonlinear distortion in music playback affects listeners vital responses, as evidenced by significant differences in both mean PPI and RMSSD, as assessed by Cochran's Q test at the 5% significance level.
ER  -