  We engineered an interactive music system that influences a user's breathing
rate to induce a relaxation response. This system generates ambient music
containing periodic shifts in loudness that are determined by the user's own
breathing patterns. We evaluated the efficacy of this music intervention for
participants who were engaged in an attention-demanding task, and thus
explicitly not focusing on their breathing or on listening to the music. We
measured breathing patterns in addition to multiple peripheral and cortical
indicators of physiological arousal while users experienced three different
interaction designs: (1) a "Fixed Tempo" amplitude modulation rate at six beats
per minute; (2) a "Personalized Tempo" modulation rate fixed at 75\% of each
individual's breathing rate baseline, and (3) a "Personalized Envelope" design
in which the amplitude modulation matches each individual's breathing pattern
in real-time. Our results revealed that each interactive music design slowed
down breathing rates, with the "Personalized Tempo" design having the largest
effect, one that was more significant than the non-personalized design. The
physiological arousal indicators (electrodermal activity, heart rate, and slow
cortical potentials measured in EEG) showed concomitant reductions, suggesting
that slowing users' breathing rates shifted them towards a more calmed state.
These results suggest that interactive music incorporating biometric data may
have greater effects on physiology than traditional recorded music.
