# A Comparison of the Effects of Binaural Beats of Audible and Inaudible Frequencies on Brainwaves
## 3 Results  
Two-way ANOVA results showed that the increase in relative alpha power was more significant in the stimulation phase than in the rest phase in all brain regions, as shown in Table 1. However, there was no difference between the two baseline frequencies (states). There was an interaction effect between the frontal and central regions. Therefore, the variation according to the phase of the two baseline frequencies differed. To interpret the interaction effect, a simple effect test was conducted on the frontal and central regions(Table 2). As a result, in the case of audible BB in the frontal region, alpha power significantly increased during the stimulation phase compared to the rest phase (\(p\) = 0.017). In the central region, alpha power significantly increased during the stimulation phase compared to the rest phase for both audible and inaudible BBs (audible \(p\) = 0.002, inaudible \(p\) = 0.012). In addition, no differences were recognized for both frontal and central states (Figure 2). The increase in relative alpha power caused by the stimulus was greater with audible sounds than with inaudible sounds (Figure 2). This was verified by an independent t-test analysis of the difference in the rate of increase (stimulation-rest/rest \(\times\) 100) in relative power between the two baseline frequencies (audible and inaudible). The rate of increase in the relative alpha power was greater in both regions when the sound was audible (Figure 3). \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & & \multicolumn{2}{c}{**Type III**} & \multicolumn{2}{c}{**Degree of**} & \multicolumn{2}{c}{**Mean**} & \multicolumn{1}{c}{**F Value**} & \multicolumn{1}{c}{**Significance**} \\  & & **Sum of Squares** & **Freedom** & **Square** & **F Value** & **Significance** \\ \hline \multirow{3}{*}{Frontal} & Phase & 0.001 & 1 & 0.001 & 4.648 & 0.037 \({}^{\star}\) \\  & State & 0.003 & 1 & 0.003 & 0.949 & 0.336 \\  & Phase \(\times\) State & 0.001 & 1 & 0.001 & 4.831 & 0.034 \({}^{\star}\) \\ \hline \multirow{3}{*}{Central} & Phase & 0.002 & 1 & 0.002 & 20.152 & \(p<\) 0.001 \({}^{\star}\) \\  & State & 0.005 & 1 & 0.005 & 1.323 & 0.257 \\  & Phase \(\times\) State & 0.000 & 1 & 0.000 & 4.229 & 0.046 \({}^{\star}\) \\ \hline \multirow{3}{*}{Farietal} & Phase & 0.005 & 1 & 0.005 & 19.232 & \(p<\) 0.001 \({}^{\star}\) \\  & State & 0.010 & 1 & 0.010 & 1.409 & 0.242 \\  & Phase \(\times\) State & 0.001 & 1 & 0.001 & 2.478 & 0.123 \\ \hline \multirow{3}{*}{Temporal} & Phase & 0.001 & 1 & 0.001 & 8.262 & 0.006 \({}^{\star}\) \\  & State & 0.004 & 1 & 0.004 & 1.167 & 0.286 \\ \cline{1-1}  & Phase \(\times\) State & 0.000 & 1 & 0.000 & 2.390 & 0.130 \\ \hline \multirow{3}{*}{Occipital} & Phase & 0.006 & 1 & 0.006 & 11.351 & 0.002 \({}^{\star}\) \\  & State & 0.005 & 1 & 0.005 & 0.462 & 0.501 \\ \cline{1-1}  & Phase \(\times\) State & 0.001 & 1 & 0.001 & 2.017 & 0.163 \\ \hline \hline \end{tabular} \({}^{\star}\): \(p<\) 0.05, \({}^{\star\star}\): \(p<\) 0.01, \({}^{\star\star\star}\): \(p<\) 0.001.  
\end{table} 
Table 1: Results of the relative alpha power of a two-way analysis of variance (ANOVA) by using phase and state as independent variables at the five brain areas.