Enhancing the regulatory function of the autonomic nervous system using sounds with inaudible high-frequency components

Figures

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  Fig. 1. Mean values of the HF, SCL, and DST for each task condition (N-back and relaxation) across the older and younger groups. The error bars represent the standard error of the mean. A p value less than 0.05 was considered statistically significant. The blue and pink bars correspond to the N-back and relaxation conditions, respectively. The task condition exhibited significant main effects in all indices. In addition, the age group had significant main effects on the HF and DST. No significant interaction effects were observed between the task condition and age group for any of the indices.

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  Fig. 2. Mean values of the HF, SCL, and DST during the N-back task condition across the whole group, older group, and younger group. The error bars represent the standard error of the mean. A p value less than 0.05 was considered statistically significant. The blue, pink, and gray bars correspond to the high-cut sound (HCS), full-range sound (FRS), and no-sound (NS) conditions, respectively. For the HF, the significant main effects of the sound condition were detected in the whole and older groups. Post hoc comparisons with Holm’s correction indicated that the HF values were significantly higher in the FRS condition than in the HCS condition (whole group: p = 0.0425; older group: p = 0.0436). For SCL, the significant main effect of the sound condition was observed only in the older group, with higher values observed in the FRS condition than in the HCS condition (p = 0.0410). The sound condition did not have significant main effects on the DST in any of the groups.

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  Fig. 3. Mean values of the HF, SCL, and DST during the relaxation condition across the whole group, older group, and younger group. The error bars represent the standard error of the mean. A p value less than 0.05 was considered statistically significant. The blue, pink, and gray bars correspond to the high-cut sound (HCS), full-range sound (FRS), and no-sound (NS) conditions, respectively. For DST, the significant main effect of the sound condition was observed in the whole group. Post hoc comparisons with Holm’s correction showed that the DST values were significantly higher in the FRS condition than in the HCS condition (p = 0.0100). In the older group, although the main effect of the sound condition did not reach statistical significance, the DST values were more likely to be higher in the FRS condition than in the HCS condition (p = 0.100). The sound condition did not have significant main effects on the HF or SCL in any of the groups during the relaxation condition.