# Relationship between Subjective and Biological Responses to Comfortable and Uncomfortable Sounds
## 3 Results and Discussion
### Factor Analysis  
Factor analysis was conducted based on the maximum likelihood method with pro-max rotation. The number of factors was set at three by following the Kaiser-Guttman \"Eigenvalues greater than one\" criterion [47; 48]. The factor loadings with the contribution ratio obtained from the analysis results are shown in Table 2. For each adjective, the factor with the highest factor loading is marked with a yellow marker. The factors were named as follows in consideration of the characteristics of their constituent items and their factor loadings: The first factor is the \"comfort factor\" and consists of \"comfortable\", \"beautiful\", \"clear\", and \"pleasant\". The second factor is the \"timbre factor\" and consists of \"rich\" and \"metallic\". The third factor is the \"power factor\" and consists of \"powerful\" and \"noisy\". The contribution rate of the comfort factor was the largest at 34%. From the cumulative contribution rate of all the factors, these three factors accounted for 80% of the contribution of all factors.  
Figure 7a,b show the averaged factor scores and their SDs of the comfort and timbre factors (Figure 7a) and the power and timbre factors (Figure 7b), respectively. From these results, SB indicated a contrasting impression compared to SA, and was rated as a sound with a higher comfort score and lower timbre and power scores. Based on the above results, it can be suggested that white noise and murumuring river sounds can be separately perceived as uncomfortable and comfortable sounds, respectively, for the majority of people.  
\begin{table}
\begin{tabular}{l l l l l l} \hline  & & & **Factor 1** & **Factor 2** & **Factor 3** \\ \hline Beautiful & - & Dirty & 0.78 & 0.18 & \(-\)0.13 \\ Clear & - & Dull & 0.73 & 0.16 & \(-\)0.19 \\ Comfortable & - & Uncomfortable & 0.55 & 0.32 & \(-\)0.24 \\ Smooth & - & Rough & 1.12 & \(-\)0.35 & \(-\)0.14 \\ Unsentimental & - & Sentimental & \(-\)0.43 & \(-\)0.24 & \(-\)0.37 \\ Loud & - & Calm & \(-\)0.74 & \(-\)0.21 & 0.05 \\ Bright & - & Dark & 0.43 & 0.38 & \(-\)0.18 \\ Low-pitched & - & High-pitched & 0.47 & 0.32 & 0.38 \\ \hline Moist & - & Dry & 0.45 & 0.48 & \(-\)0.17 \\ Poor & - & Rich & 0.01 & \(-\)0.70 & \(-\)0.07 \\ Large & - & Small & 0.10 & 0.81 & \(-\)0.04 \\ Soft & - & Hard & 0.21 & 0.67 & \(-\)0.07 \\ Metallic & - & Not metallic & \(-\)0.23 & \(-\)0.70 & \(-\)0.49 \\ \hline Powerless & - & Powerful & \(-\)0.12 & 0.13 & \(-\)0.87 \\ Quiet & - & Noisy & 0.12 & \(-\)0.42 & \(-\)0.69 \\ \hline \multicolumn{2}{c}{Contribution ratio} & 0.34 & 0.28 & 0.18 \\ \multicolumn{2}{c}{Cumulative contribution ratio} & 0.34 & 0.62 & 0.80 \\ \hline \end{tabular}
\end{table}
Table 2: Results of the factor loadings and the contribution ratio of the 15 adjectives for each factor of factors 1, 2 and 3 obtained from the factor analysis. For each adjective, the factor with the highest factor loading is marked with a yellow marker. The first, second and third factors are named the “comfort factor”, “timbre factor” and “power factor”, respectively. The contribution rate of the comfort factor was the largest at 34%.