# Calculation of 1/f Fluctuation from Sound Signal and Comfort Evaluation
## 2 Calculation Method for Fluctuation Coefficient of the Sound Signal
### Consideration for the Impression of the Sound Signal  
Figure 12 shows the evaluation items selected by 10 or more participants according to the impression of the music that the participants felt more comfortable with. The vertical axis shows the evaluation items, and the horizontal axis denotes the number of people. The blue bar denotes the number of participants who selected the evaluation items as the impression of music A when they were comfortable listening to music A (note that the frequency coefficient of variation for A was far from \(-1\)). The red bar denotes the number of participants who selected the evaluation items as the impression of music B when they were comfortable listening to music B (note that the frequency coefficient of variation for B was close to \(-1\)). From the results, we observed that when people felt comfortable, they tended to choose Clear, Calm, Deep, Luxury, and Beautiful. Figure 13 shows the adjectives typically chosen by participant groups according to the music that they chose. In this figure, (a) shows the adjectives chosen by the participant group who felt that music A was comfortable; (b) shows the adjectives chosen by the participant group who felt that music B was comfortable. Both results exhibited a difference of five or more in the selected evaluation items. According to (a), many people who felt comfortable with music A chose Clear, Not Muffled, Awaking, Strong, and Powerful. Therefore, we considered that these participants tended to be comfortable when they  
Figure 11: Example of a participant selecting impression items in a free-answer format. Figure 12: Adjectives typically chosen by participants who felt more comfortable. listened to music that gave an easy-to-understand impression and had a large sound intensity. Moreover, according to (b), many people who felt comfortable with music B chose Vague, Calm, and Sleepy. Therefore, we considered that these participants tended to report that they felt comfortable when they felt physically and mentally stable by listening to music B. Furthermore, there was a difference between the answers Do Not Care and Quiet. According to this result, we considered that a person who listened to music B and felt comfortable did not care about the sound signal itself, even if the person listened to the music at a particular sound pressure level and had a quiet environment. Figure 14 shows the results of the impression evaluation in which more than 10 participants identified a difference between music A and B. From this result, we observe that many people who feel comfortable with music A tend to answer Clear, Strong, and Powerful. Moreover, many people who feel comfortable with music B tend to answer Vague and Sleepy. Figure 13: Adjectives typically chosen by participant groups for each music piece. (**a**) The adjectives chosen by the participant group who felt that music A was comfortable. (**b**) The adjectives chosen by the participant group who felt that music B was comfortable. Considering the above results, we conducted a multiple regression analysis for the result of the impression of sound signal for all participants. Table 1 shows the result of the \(p\)-value for each of the 21 evaluation items; 21 of the 38 items in this table are shown in Figures 12-14. The \(p\)-values indicate the significant probability of the selection that affects music A and B. If the \(p\)-value was 0.05 or less, it meant that the evaluation items had an effect on the selection between music A and B. According to the results, Strong had a \(p\)-value of 0.01, indicating a significant difference. Strong was an evaluation item that could cause a significant difference when used as a question to clarify the difference in comfort when a person listened to music with different frequency fluctuation coefficients.