EEG power spectrum changes due to listening to pleasant music and their relation to relaxation effects.

Electroencephalogram (EEG) power spectrum changes induced by pleasant music (2-min. fractions of 6 samples of music [famous classical and commercially available "alpha music" at 10-sec. intervals]) were investigated in relation to changes in 16 kinds of psychosomatic feelings. Subjects were 42 healthy young people aged 18-25 yrs. Two major components, "pleasant & relaxed" and "calm", were extracted through principal component analysis of the feeling changes, both of which were related to the "relaxation effects" of the music. These component scores were not related to the changes of EEG powers in the delta, theta, alpha and beta frequency components in 6 regions (frontal, parietal and occipital regions of the left and right hemispheres), when examined separately. However, the change of the total delta power for all the regions was significantly associated with both the "pleasant & relaxed" and "calm" component scores. The association between the total theta power change and "calm" score was found to be insignificant if the type-A personality variable was added to their regression model. On the other hand, the alpha-peak frequency was inversely related to the decrease of the "calm" score in the left occipital region (LO). The reduction of the alpha-peak power in the LO was also significant, and was associated not with the alpha-peak frequency changes but inversely with the "calm" score, although these alpha-component changes were not shown to be modified by the personality. Thus, the present study suggests, as a preliminary finding, that the "relaxation effects" of pleasant music can be associated with the EEG power spectrum component changes, especially with the change in the total theta power and possibly with that in the alpha power in the occipital, and the frequency shift of the peak in the alpha-range. Some of the associations were also shown to vary for the type-A personality, suggesting a clue to relating the personality to a differential stress-related psychosomatic trait, although the physiological significance of the changes in the low-frequency component range as well as those in the alpha-frequency component, which are obtained through FFT, should be further clarified.