## 1 Introduction  
With the rapid development of new energy vehicles, people not only have higher requirements for the safety and power of vehicles, but also have certain requirements for the comfort of vehicles. Research shows that when the driving speed of a vehicle reaches 100 km/h, the noise in the passenger compartment is mainly aerodynamic noise [1, 2]. When the vehicle is running at high speed, the vehicle body surface and air interact with each other, and an aerodynamic noise source is generated in the near-wall turbulence zone near the vehicle body and radiates noise to the surroundings. In all parts of the vehicle, the noise source in the rearview mirror and A-pillar area are the main source of aerodynamic noise in the vehicle [3]. Therefore, it is of great significance to study the aerodynamic noise source in the rearview mirror area. Recently, research on aerodynamic noise has made great progress. For the study of aerodynamic noise in the rearview mirror area, numerical simulation is mainly used to explain the cause of aerodynamic noise according to the flow separation phenomenon and pressure pulsation in the flow field, and then the aerodynamic noise can be controlled by controlling the local structure of the rearview mirror. [PERSON], [PERSON], et al. [4] studied the influence of different installation positions of the rearview mirror on the aerodynamic noise in the vehicle, and concluded that the aerodynamic noise in the vehicle is relatively small when the rearview mirror is installed in the door position. [PERSON], [PERSON], et al. [5; 6] studied the influence of the rearview mirror cover edge and different rearview mirror shapes on aerodynamic noise, and found that the construction of grooves on the rearview mirror cover edge had a significant impact on the structure and position of the vorticity at the rear of the rearview mirror; the research revealed the law of the influence of different rearview mirror shapes on the flow field. [PERSON], [PERSON], et al. [7] studied the influence of three shape parameters and two installation angle parameters of the rearview mirror on the aerodynamic noise and reported that the windward angle of the rearview mirror, the length of the bracket, and the thickness in front of the rearview mirror are the key structures affecting the aerodynamic noise. In terms of aerodynamic noise source, [PERSON], [PERSON], et al. [8] established the relationship between the radiated sound pressure of a dipole sound source and the pressure gradient in the flow field according to the relationship between the radiated sound pressure in the flow field and the pulsating pressure and the pressure gradient in the flow field, and established an identification method for sound source in the flow field. [PERSON], [PERSON], et al. [9] simulated the aerodynamic noise of a high-speed magnetic levitation train based on the Lighthill acoustic analogy theory using finite element analysis, showing that the aerodynamic noise of high-speed magnetic levitation train is a kind of broadband noise, and the noise source is mainly distributed in the areas of airflow separation and turbulence intensity such as the head car and the tail car's streamlined shoulder. [PERSON], [PERSON], et al. [10] calculated the main sources of aerodynamic noise of a high-temperature superconducting magnetic levitation train based on large-vortex simulation and the K-FWH equation. It was shown that the dipole sound sources were mainly distributed on both sides of the roof surface of the middle car, the tail streamer, and behind the superconducting coil. Quadrupole sound sources made significant contributions in the tail flow area, and the energy share of quadrupole sound sources increased with the increase of speed. [PERSON], [PERSON], et al. [11] considered a high-speed magnetic levitation train as a research object to study the spatial distribution characteristics of aerodynamic noise sources at different speeds.