The purpose of this study is to survey the effect of sound waves on the change in brain waves. This test was organized into two steps. The first step was to give a sound stimulus to each subject in U4, V4, and Z2. And to measure the brain waves of the subjects, the second step, called a preference test, was performed, which allowed subjects to choose their favorite sounds. After 6 times of stimulus their reactions were measured for 5 minutes. The subjects were divided into 4 groups according to the results of STAI-KYZ tests: the first group had lowed normal mentality grades; the second group had high grades in normal mentality; the third group had low grades in emotional instability; the fourth group had high grades in emotional instability. The differences in beta and mid-alpha waves of these groups before and after the test were analysed. The results showed that the high group of normal mentality and emotional instability remained steady before the test. Also, the high group of normal mentality and emotional instability showed eased tensions before and after the test. The average of beta and mid-alpha waves before and after sound stimuli of U, V, and Z was analyzed. The results showed that U sounds had the most relaxing effects. The sound waves that each subject had preference showed a more relaxing effect. These results revealed that the high groups of normal mentality and emotional instability had a more relaxing effect rather than the low groups, which means that individual musical preferences and experiences cause a reaction.