Investigating Musical Modes through Heart Rate Variability and Designing a Hemi-Anechoic Chamber for Controlled Replication

Musical modes are known to evoke unique emotional responses in listeners, with major modes typically associated with positive affect and minor modes with negative affect. In the past, studies have used heart rate variability (HRV) as a physiological marker to infer certain stress responses to stimuli. In this pilot study, participants (n=12) listened to five audio tracks: baseline pink noise, two major mode, and two minor mode. The major and minor tracks alternated, with the order counterbalanced between participants. For each track, HRV data was collected using PolarH10 sensors through the EliteHRV app. The HRV metrics collected for analysis included the root mean square of successive difference (RMSSD), high frequency (HF) power, and low frequency to high frequency ratio (LF/HF). In addition to the HRV data, after each track, listeners also completed a survey on their perceived stress levels. Each of the metrics were compared across conditions (control, major, minor) using separate one-way ANOVA tests in SPSS. Preliminary results from the HRV data seem to suggest that listeners were the least stressed when listening to the pink noise track and most stressed when listening to the minor mode track. To improve future testing conditions, we began constructing a hemi-anechoic chamber, which simulates a free-field environment, to provide an acoustically controlled space. As the chamber was built, we measured sound transmission loss, reverberation time, and impulse response to evaluate the impact of adding different materials. This chamber will allow for future perceptual and musical studies to be better controlled acoustically.