## 4 Discussion  
Based on the results of the ANOVA in Section 3.1 (shown in Table 3), the influence of reverberation time on knowledge creative activities by multiple people was small in the 3000 m\({}^{3}\) space within a reverberation time from about 0.6 s to 2 s (average sound absorption coefficient from 0.16 to 0.44). [PERSON]'s \"Arabesque No. 1\", which was used as the classical music in our study, has been shown to reduce oxygenated hemoglobin (Oxy-Hb) concentrations in the cerebral bloodstream and to be effective for relieving stress [31]. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Objective Variable** & \begin{tabular}{c} **Adjusted Coefficient** \\ **of Determination** \\ \end{tabular} & **Explanatory Variable** & \
\begin{tabular}{c} **Standardized** \\ **Partial Regression** \\ **Coefficient** \\ \end{tabular} \\ \hline Good conversation & 0.907 &
\begin{tabular}{c} Ease of talking \\ **Ease of** \\ **communicating own** \\ **voice to others** \\ **Quietness** \\ **Liveliness** \\ **Relaxation** \\ \end{tabular} & 0.183 * \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Results of the multiple regression analysis. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & **Ease of** & \
\begin{tabular}{c} **Ease of Communica** \\ **Talking** \\ \end{tabular} &
\begin{tabular}{c} **Quietness** \\ **Own Voice to** \\ **Others** \\ \end{tabular} & **Liveliness** & **Relaxation** \\ \hline Ease of talking & - & - & - & - & - \\ Ease of & & & & & \\ communicating own & 1.44 & - & - & - & - \\ voice to others & & & & & \\ Quietness & 1.00 & 1.33 & - & - & - \\ Liveliness & 1.12 & 1.00 & 1.11 & - & - \\ Relaxation & 1.18 & 1.37 & 1.21 & 1.01 & - \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Variance inflation factors of the evaluation items in the psychological model. Considering this and the results shown in Figure 5, the classical music used in our study gave the participants a relaxing feeling. A previous study examining the impact of classical music ([PERSON], [PERSON], [PERSON], and [PERSON]) on creative tasks reported that participants who listened to \"happy music\" (i.e., classical music that produces arousal and a positive mood) while conducting a divergent creativity task were more creative than those who performed the task silently [20]. In addition, that study concluded that \"happy music\" had no effect on convergent creativity. Another previous study comparing the music of [PERSON] and [PERSON] [32] reported that participants performed better on a test of spatial abilities after listening to a [PERSON] sonata than after sitting in a quiet condition and that a slow \"sad\" musical excerpt from [PERSON] had no influence on a creative task. Participants listening to [PERSON] showed significantly higher positive feelings and arousal (e.g., enjoyment rating, mood rating, Profile of Mood States [POMS] arousal score) and significantly lower negative feelings (e.g., POMS mood score) than did those who listened to [PERSON]. As mentioned above, some studies have shown that \"happy music\" has more of an effect on creative work efficiency compared with a silent condition but that neither \"calm\" nor \"sad\" music improves creative work efficiency. By contrast, although [PERSON]'s \"Arabesque No. 1\" was used in this study as \"calm (relaxing)\" music in our experiments, a significant positive effect on knowledge-creative activity was observed. The studies mentioned above examined the influence of classical music on a creative task performed alone, but the present study focused on the effects on knowledge creative activities performed by multiple people; this was considered the reason for the differences in the influence of music. Our findings, therefore, clarified the effectiveness of using an evaluation structural model of the sound environment to examine the effects of different sound stimuli on knowledge creative activities performed by multiple people.