## 5 Discussion  
This study aimed to verify that the affective response of the engine acceleration sound through acoustic parameters based on RPM occurs even for consumers who have no empirical knowledge about the automobile sound. In addition, it is found that a model can be designed to predict affective dimensions through acoustic parameters. As a result of the analysis, it was found that the engine acceleration sound developed a specific affective response of customers and the acoustic parameters based on RPM were suitable for explaining the affective response. It can be assumed that the subjects \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**Affective Dimension** & **Acoustic Parameter** & **B** & **Error** & \(\beta\) & **F** & \(p\) & **VIF** & **R\({}^{2}\)** \\ \hline \multirow{6}{*}{Refined} & Constant & 1.430 & 0.592 & & 2.414 & 0.022 & & \\  & SPL\({}_{3500}\)-5000 & 0.045 & 0.009 & 0.542 & 4.902 & 0.000 & 3.708 & \\  & Sharpness\({}_{2000}\)-5000 & \(-3.311\) & 0.280 & \(-0.960\) & \(-11.838\) & 0.000 & 1.996 & 0.892 \\  & Fluctuation\({}_{2000}\)-5000 & \(-0.481\) & 0.107 & \(-0.281\) & \(-4.506\) & 0.000 & 1.184 & \\  & SPL-A\({}_{3500}\)-5000 & 0.023 & 0.007 & 0.423 & 3.094 & 0.004 & 5.682 & \\ \hline \multirow{6}{*}{Powerful} & Constant & 10.688 & 0.544 & & 8.093 & 0.000 & & \\  & SPL\({}_{2000}\)-5000 & \(-0.114\) & 0.215 & \(-0.966\) & \(-4.237\) & 0.000 & 8.471 & \\ \cline{1-1}  & SPL-A\({}_{2000}\)-5000 & 0.134 & 0.107 & 1.726 & 8.936 & 0.000 & 3.552 & 0.936 \\ \cline{1-1}  & SPL\({}_{2000}\)-3500 & \(-0.051\) & 0.083 & \(-0.397\) & \(-3.849\) & 0.001 & 5.201 & \\ \hline \hline \end{tabular}
\end{table} 
Table 10: Results of regression analysis of affective dimensions for all acoustic parameters. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Affective Dimension** & **Acoustic Parameter** & **B** & **Error** & \(\beta\) & **F** & \(p\) & **VIF** & **R\({}^{2}\)** \\ \hline \multirow{6}{*}{Refined} & Constant & 0.597 & 0.754 & & 0.792 & 0.434 & & \\  & SPL\({}_{3500}\)-5000 & 0.065 & 0.012 & 0.835 & 6.951 & 0.000 & 0.780 & \\  & Sharpness\({}_{3500}\)-5000 & \(-1.793\) & 0.231 & \(-0.707\) & \(-4.757\) & 0.000 & 0.818 & \\  & Roughness\({}_{3500}\)-5000 & \(-0.352\) & 0.114 & \(-0.192\) & \(-2.265\) & 0.031 & 0.949 & \\ \hline \multirow{6}{*}{Powerful} & Constant & 10.266 & 0.644 & & 5.472 & 0.000 & & \\  & Tonality\({}_{3500}\)-5000 & 2.755 & 0.547 & 0.277 & 3.481 & 0.001 & 0.782 & \\ \cline{1-1}  & SPL\({}_{2000}\)-3500 & \(-0.146\) & 0.360 & \(-1.133\) & \(-4.376\) & 0.000 & 0.382 & \\ \cline{1-1}  & SPL-A\({}_{3500}\)-5000 & 0.110 & 0.027 & 1.339 & 5.831 & 0.000 & 0.332 & \\ \hline \hline \end{tabular}
\end{table} 
Table 9: Results of regression analysis of affective dimensions for acoustic parameters from 2000 to 3500 and 3500 to 5000 RPM. heard the engine acceleration sound for each automobile and recognized the developed affective dimensions relatively accurately. As a result of the factor analysis, two representative factors: 'Powerful' and 'Refined' in the engine acceleration sound were extracted. Previous studies on automobile sounds that explored the relationship with various acoustic parameters, where 'Luxurious' and 'Sporty' were the representative affective dimension [45; 46]. [PERSON] et al. [41], have shown that the degree of the auditory affect felt by the driver varies depending on two driving circumstances. In the case of constant speed, two factors: 'Pleasant' and 'Metallic' were selected in 15 affective adjectives, but in the case of acceleration speed, three factors: 'Powerful', 'Pleasant' Three factors of 'Metallic' were selected as 16 affective adjectives. [PERSON] et al. [47] derive three representative affective adjective factors for sound interior sound in the truck. [PERSON] et al. [48] selected 15 affective adjectives that user-perceived door sound in an automobile. From the factor analysis, three representative affective dimensions: metallic, pleasant, and powerful were derived.