OBJECTIVE: This study was undertaken to develop a new autonomic scoring scale distinct from the conventional sympathetic or parasympathetic parameters cardiac autonomic response. METHODS: The parameters were obtained from a log-log scale of frequency (f ) vs. power spectral (P) amplitude of heart rate variability (HRV). A gradient value in which the graph decreases towards a high frequencies on the X-axis, while showing an absolute value beta itself based on the formula \'P = f (-beta)\' was newly named the \'Balance index\' by implying a balanced state in the living body. The index was categorized into four bands based on the appearance of the whole frequency ranges (T-Balance Index). Therefore, we compared the responses of the following groups: the patient test group (Group PT), the normal test group (Group NT), and the normal non-test group (group NN). RESULTS: Significant differences in parameters were observed among the three groups. In addition, the difference between the \'High-side Balance Index\' and the \'Low-side Balance Index\' was 0.75 +/- 0.12 vs. 0.07 +/- 0.04 (p < 0.005) for groups NT vs. PT. This novel analyzing method was useful for evaluating the subtle changes in a living body to regulate the living-power (strength of vitality). Moreover, the difference between the \'T-Balance Index\' and \'SV-Balance Index\' was 0.18 +/- 0.12 vs. -0.21 +/- 0.15 (p < 0.01) for groups NT vs. PT. CONCLUSIONS: One application of new parameters \'Balance Index\' is its ability to evaluate the vital or emotional functions of unconscious patients in a critical condition undergoing a sense challenge test. This method assists in improving our ability to measure the early stage of conscious recovery with greater accuracy by using our novel analysis method for performing senses challenge test, with the aid of media such as music.