# Effect of Audio-Visual Factors in the Evaluation of Crowd Noise
## 3 Results  
### Effect of Human Voice Volume and Other Sounds on Acoustic Evaluation  
IBM SPSS Statistics 21.0 was used to establish a database with all results. The acoustic evaluations of human voice volume and sound types are shown in Table 1 (SD means Standard Deviation). In terms of acoustic comfort, people had positive attitudes toward the natural sound, while the opposite was true for mechanical sound [4; 43; 44]. The trend in sound preferences was similar to the trend in acoustic comfort. That is, sounds with higher  
Figure 3: Contents of questionnaire and specific evaluation indicators. acoustic comfort also had higher sound preference evaluations, consistent with previous studies [24,32]. Table 2 shows the significance of the indicators under the main effect. Mixed design analyses of variance (ANOVAs) were run to test the differences in mean ratings between subgroups divided by the two main variables. Sound type and volume were taken as independent variables. The results showed that in the three sound sources, the main effect of sound types and volume levels, and the interaction between them all, had significant effects on sound loudness, acoustic comfort, and sound preference (\(p<0.05\)). A one-way ANOVA was run to test the differences in mean ratings between the subgroups divided by the variables that interacted. After removing the factors without statistical significance, the model was simplified. Figure 4 shows the evaluation of the acoustic metrics after superimposing the human voice with different sound types (birdsong, traffic sounds, and music) under the auditory-only stimuli. (The error bars represent the standard deviation [S.D.] of the average values.) In terms of loudness, there was an interaction between the type of sound and the volume. With respect to sound types, regardless of the variation in volume level, the loudness of the human voice after superimposing bird sounds and musical sounds was rated lower than that of traffic noise. When the participants heard the first two sound types, they did not feel the sound loudness as much. The participants \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Sound Types**} & \multirow{2}{*}{**Human Voice Volume**} & \multicolumn{2}{c}{**Acoustic Comfort**} & \multicolumn{2}{c}{**Sound Preference**} & \multicolumn{2}{c}{**Sound Loudness**} \\ \cline{3-8}  & & **Mean** & **SD** & **Mean** & **SD** & **Mean** & **SD** \\ \hline \multirow{3}{*}{Traffic} & Low & 2.50 & 0.67 & 2.38 & 0.83 & 3.47 & 0.80 \\  & Medium & 2.47 & 0.67 & 2.19 & 0.64 & 4.00 & 0.58 \\  & High & 1.88 & 0.98 & 1.75 & 0.72 & 4.5 & 0.72 \\ \hline \multirow{3}{*}{Bird} & Low & 3.66 & 0.87 & 3.53 & 0.92 & 2.81 & 0.86 \\  & Medium & 3.16 & 0.63 & 3.06 & 0.72 & 3.16 & 0.72 \\  & High & 1.47 & 0.57 & 1.38 & 0.55 & 4.41 & 0.80 \\ \hline \multirow{3}{*}{Music} & Low & 3.94 & 0.91 & 4.16 & 0.85 & 2.84 & 0.68 \\  & Medium & 3.28 & 0.81 & 3.34 & 0.90 & 3.38 & 0.71 \\ \cline{1-1}  & High & 2.38 & 0.87 & 2.16 & 0.72 & 4.38 & 0.66 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Acoustic evaluation. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Source** & **Acoustic Comfort** & **Sound Preference** & **Subjective Loudness** \\ \hline Traffic & **0.02** & **0.00** & **0.00** \\ Birds & **0.00** & **0.00** & **0.00** \\ Music & **0.00** & **0.00** & **0.00** \\  & Low volume & & \\ Traffic + Birds & **0.00** & **0.00** & **0.00** \\  & Birds + Music & 0.36 & **0.01** & **0.00** \\ Traffic + Birds + Music & **0.00** & **0.00** & **0.00** \\  & Medium volume & & \\ Traffic + Birds & **0.00** & **0.00** & **0.00** \\  & **0.00** & **0.00** & **0.00** \\  & Birds + Music & 0.76 & 0.31 & 0.40 \\ Traffic + Birds + Music & **0.00** & **0.00** & **0.01** \\  & High volume & & \\ Traffic + Birds & 0.12 & **0.07** & 0.86 \\ Traffic + Music & **0.04** & **0.05** & 0.77 \\ Birds + Music & **0.00** & **0.00** & 0.98 \\ Traffic + Birds + Music & **0.02** & **0.04** & 0.68 \\ \hline \hline \end{tabular} Note: significance (\(p<0.05\)) is in bold.  
\end{table}