Baroreflex Sensitivity During Listening to Music Computed from Time Domain Sequences and Frequency Domain Transfer Function.

Listening to music has been known to affect autonomic function of cardiovascular regulation. Baroreflex is a feedback control loop that uses rate changes of the heart in order to regulate beat by beat changes in blood pressure (BP). In this study, we used two approaches to compute measures of sensitivity of the baroreflex (BRS), a time domain sequence approach and frequency domain transfer functions. Subjects listened to slow and fast tempo songs during the study. Electrocardiogram (ECG) and non-invasive continuous BP were recorded in 14 subjects (7 males and females). From these signals, either beat by beat or equi-sampled in time RR intervals and systolic BP (SBP) were computed. BRS was then estimated using RR and SBP. Our results show that the sequence method consistently provided higher values of BRS than the transfer function method (up to two fold). The two measures were reasonably well correlated $( \mathrm {R}>0.84)$ during control and the slow song, but not during the fast song. The BRS was lower $( \sim 20$%) than control when listening to fast songs $( \mathrm {p}<0.005)$. These results show the effects of listening to songs on BRS changes, but also show that the two methods to estimate BRS, although reasonably correlated, do not always provide similar estimates of BRS.