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. 2014 Apr 30;9(4):e95464. doi: 10.1371/journal.pone.0095464

Figure 5. Results of Experiment 2: detailed examinations of frequency dependency of the hypersonic effect.

Figure 5

A: Mean (+SE) values of ΔAlpha-2 EEG across the subjects in each of twelve sub-experiments. The frequencies indicate the frequency range of HFC that were applied together with LFC ([LFC+HFC]) in comparison with the control ([LFC] alone). ΔAlpha-2 EEG is calculated by subtracting Alpha-2 EEG obtained during [LFC] from those during [LFC+HFC] in each subject. Univariate ANOVA showed the main effect of the frequency of HFC (p<0.05). Tukey's post-hoc tests showed a significant difference between ΔAlpha-2 EEG obtained with [LFC+HFC16-24] and that obtained with [LFC+HFC80–88] (p<0.05). B: Comparison of ΔAlpha-2 EEG between two groups of pooled data obtained in the sub-experiments using HFC below 32 kHz and those obtained in the sub-experiments using HFC above 32 kHz. Unpaired t-tests showed significant difference between the two groups and 1-sampled t-tests showed significant difference from zero for each group, that is, ΔAlpha-2 EEG obtained by using HFC below 32 kHz was significantly negative (p<0.01), while those obtained by using HFC above 32 kHz was significantly positive (p<0.001).