## 7 Conclusions  
1. The development trend of EV in-vehicle sound has been investigated and researched, and the concept design goal of in-vehicle sound with \"both comfort and dynamic sense sound quality characteristics\" has been formulated. Combined with the subjective evaluation method and test results, a sound design method is proposed for the vehicle under uniform speed, which mainly considers three dimensions of engine order composition, spectral energy distribution, and sound amplitude enhancement in typical speed range.  
\begin{table}
\begin{tabular}{c c c} \hline
**Evaluate Sample Vehicle and Condition** & **Subjective Evaluation Score of Comfort** & **Subjective Evaluation Score of Dynamic** \\ \hline PEV original state & 6.0 & 6.0 \\ PEV, ASGS work normally & 6.5 & 6.2 \\ A coupe-type FV & 7.5 & 6.8 \\ \hline \end{tabular}
\end{table}
Table 16: Subjective evaluation score record of real vehicle at constant speed.  
Figure 40: Sound quality distribution of three sample vehicles under uniform driving conditions.  
2. The in-vehicle sound spectrum of the FV is analyzed, and the sound simulation analysis of the engine order is completed. The short-time Fourier transform (STFT) is used to synthesize the engine order sound in the vehicle, and it is verified that the STFT and synthesis technology based on Kaiser window function can meet the fitting accuracy of the engine order sound, and can be used to simulate the starting sound of the ASGS in the vehicle. 3. The sound design plan and control target of an A-class pure electric SUV under uniform speed conditions with both comfort and dynamic sense are formulated. A sound amplitude control method of active sound system is proposed based on the variation law of engine order sound amplitude and engine output power of traditional internal combustion engine vehicle. The correlation between engine order sound amplitude and dynamic sense is analyzed, and the parameter setting of EV active sound is clarified. 4. The hardware of the in-vehicle ASGS is designed, the control software of the in-vehicle ASGS is developed, the construction of the EV ASGS based on the speaker of the in-vehicle sound system is completed, and the ASGS is tested and verified. 5. When the ASGS works normally, the noise level of low amplitude is guaranteed. When the vehicle speed is 28.6 km/h, the sharpness is reduced by 0.52 acum. Combined with objective evaluation test and subjective evaluation test of a real vehicle, it is verified that the ASGS in this paper can improve the comfort and dynamic sense quality characteristics of EVs in uniform driving conditions.  
Conceptualization, S.Z., Y.L. and Y.C.; methodology, S.Z. and Y.L.; software, S.Z., Y.L. and Y.C.; validation, S.Z. and Y.L.; formal analysis, S.Z. and Y.C.; writing--original draft preparation, S.Z. and Y.L.; writing--review and editing, S.Z., Y.L. and L.X.; visualization, Y.L.; supervision, S.Z., Y.L. and L.X.; project administration, S.Z. and L.X. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the Major Science and Technology Project of Henan Province (221100240400), Key Scientific Research Project of Colleges and Universities in Henan Province (no. 20A460013) and the National Key Research and Development Program of China (no. 2017 YFD070020402).  
Not applicable.  
The authors declare no conflict of interest.