# A Novel Approach for Acute Mental Stress Mitigation Through Adapted Binaural Beats: A Pilot Study
## 3 Results
(**B**) Average heart rate for the investigated sample during the relaxing video (VID) and the mental arithmetic task (MAT). (**C**) Results of the visual analog scale (VAS) questionnaire for both the VID and MAT. Statistically significant differences are indicated with ** for \(p<0.01\). Concerning (**B,C**), the bar represents the median of the distribution. Figure 6A enriches the content of Figure 5A,B by considering the average of the stress index in each step of the protocol (except the training) for each subject. The results indicate that ABB led to statistically lower values of the average stress index compared to CBB (\(p<0.05\)), with a reduction of approximately 17% (considering the median of the distributions). As reported in Figure 5B, no statistically significant differences were detected in the VAS results for the CBB and ABB conditions. Similarly, no statistical differences were detected for the MAT performances (i.e., accuracies and reaction times). It is important to note that for Figure 6A,B, the pairwise comparisons with VIDs were omitted for brevity, despite being statistically significant. To facilitate the pairwise comparison between the CBB and ABB conditions, Figure 7A displays the average stress indexes during CBB and ABB simulations for all the participants. Furthermore, given the significant importance of the \(RR\) interval (see Figure 4A), the participants' average heart rates were estimated for the two stimulation conditions. The results are shown in Figure 7B and, except for one participant indicated in red, the ABB led to a reduction in the average heart rate. It is worth noting that the same participant also showed an increase in the average stress index, as shown in Figure 7A. In addition, we  
Figure 4: (**A**) Ranking of the features as determined by the random forest regressor. The values are reported as average values between the participants. (**B**) Ranking of the top 5 features for subject 1 (S1). (**C**) RR interval estimated during VID and MAT. (**D**) \(RT_{R}\) during the same tasks. (**E**–**G**) Same as (**B**–**D**) but for another subject, i.e., subject 2 (§S2). Figure 5: (**A**) Stress predictor (S) for the participants receiving the adapted (ABB) and constant (CBB) stimulation, with this specific order. (**B**) Similar to (**A**) but considering the participants receiving the opposite stimulation order. (**C**) \(f_{BB}\) changes during the ABB stimulation. The solid black line represents the average of the curves, each relative to one participant. investigated another temporal metric linked to parasympathetic predominance: the root mean square of successive differences (RMSSD) [47]. No statistically significant differences were found in the pairwise comparison. However, the median of the ABB distribution is higher than that of the CBB distribution, and the \(p\)-value from the statistical test (\(p=0.068\)) slightly exceeded the level of significance. Similarly to what is conducted for the previous part of the Figure 7, the participant showing worsening as a result of ABBs is also shown in red.