Abstract
Eleven male university students and 14 female university students were selected as subjects. Subjects sat with their eyes shut in a chair at rest and listened to 8 different kinds of music at loudness levels on an average of 70 db. Beat-to-beat R-R intervals were recorded continuously prior to, during listening to the music and immediately after cessation of acoustic stimuli using headphones. Data were analyzed using a fast Fourier transform algorithm. Low frequency (LF) power and high frequency (HF) power were defined as 0.04–0.15 and 0.15–0.40 Hz, respectively. The value of HF is associated with activity of the parasympathetic nervous system and LF/HF ratio is regarded as a reliable index of activity of the sympathetic nervous system. To estimate changes in cardiac autonomic function induced by listening to different kinds of music, plotting of LF and LF/HF in standard measure against HF in standard measure and plotting of LF/HF (%) against HF (%) accompanied by central area and lines of the same value of parameter R indicating state of balance in autonomic nervous system were used. Values of LF and LF/HF tended to decrease during listening and increased after cessation of listening whereas values of HF in female subjects tended to increase during listening to music. Male subjects tended to show greater values of LF and LF/HF and smaller values of HF. In male subjects, values of LF and LF/HF after cessation of listening were significantly greater than those during listening to some music. Values of LF and LF/HF after cessation of acoustic stimuli in male subjects were significantly greater than those in female subjects. Music containing familiar and a slight musical component caused lesser changes in activities of the autonomic nervous system. Smaller sound changes in music and nontonal music may be more effective to increase HF.
