## 5 Discussion  
Relationship between the Acoustic Environment around Intersections and Horn Honking and the Traffic Environment  
The analysis of the \(L_{\text{Aeq,10 min}}\) and \(L_{\text{Amax}}\) of the RTN with and without honking at intersections indicates that \(L_{\text{Amax}}\) values sometimes decreased when the noise level data of  
\begin{table}
\begin{tabular}{c c c} \hline \hline \multirow{2}{*}{**Independent Variables**} & **Standardized Partial** & \multirow{2}{*}{\(p\)**Value**} \\  & **Regression Coefficient** & \\ \hline Traffic volume of motorcycles & 0.670 & \textless{}0.001 \\ Traffic volume of standard-sized vehicles & \(-0.095\) & 0.518 \\ Traffic volume of large-sized vehicles & \(-0.030\) & 0.827 \\ Total number of exiting lanes & 0.022 & 0.883 \\ Honking frequency & 0.201 & 0.109 \\ \hline \hline \end{tabular}
\end{table}
Table 10: Result of multiple regression analysis for \(L_{\text{Aeq,10 min}}\).  
honking were removed in situations with low \(L_{\text{Aeq,10 min}}\) values. As electric cars and hybrid vehicles become more prevalent in the future, the acoustic environment near roads will improve, but as it is, the current horn system will prevent that improvement.  
The values of \(L_{\text{Aeq,10 min}}\) obtained by excluding the noise level data for horn use was almost the same as those obtained from the original data, as shown in Figure 7. The relationship between the number of honks per minute and the increment of the RTN indicated that \(L_{\text{Aeq}}\) did not increase when horn events occurred less than twice per minute [44]. In the present result, the maximum numbers of honks per minute were estimated as 2.3 at Intersection 1 and 3.3 at Intersection 2 (Figure 4). Therefore, the sound energy of honks was not supposed to affect the \(L_{\text{Aeq,10 min}}\) values.  
The acoustic environment around roads should generally be influenced by traffic volume [45]. In the surveyed sites, small motorcycles are commonly used for commuting (Table 4). To improve the acoustic environment of the surveyed sites, it is necessary to address the heavy motorcycle traffic.  
The \(L_{\text{Aeq,10 min}}\) values at Intersection 1 were lower than those at other intersections, especially during rush hours (8:00 and 18:00); nevertheless, traffic volume was very high (Figure 7). The measurement point at Intersection 1 was located on the pedestrian bridge on the west side of this intersection (Figure 2). This measurement point was located on the outside of the intersection, slightly away from the road, with many lanes in the north-south direction, which serves as an arterial road connecting Taipei City and its suburbs. Therefore, noise from the north-south traffic flow was not fully reflected in the noise level values. On the other hand, the \(L_{\text{Aeq,10 min}}\) values were higher at 9:00 and 17:00 than at other time zones due to ambulance sirens. These may be the reasons why the correlation between noise level and traffic volume was not significant (\(r=-0.05\)) only at Intersection 1 on weekday.  
This analysis also confirmed that horn honking did not significantly affect the noise levels (\(L_{\text{Aeq,10 min}}\)) at the surveyed sites. However, the multiple regression analysis for \(L_{\text{Amax}}\) indicated that the maximum noise level increased with honking frequency. It may suggest that the more frequent the honking is, the more likely it is to be reflected in the maximum values of noise levels. Therefore, a reduction of deafening horn sounds should be effective in improving the acoustic environment around intersections.