Numerical calculation and experiment investigation of sound field in the full model car

Currently, much interior sound field research in car is based on the car body that many parts are missed, which is not consistent with the actual condition. In addition, the research results have not been verified by experiment; few things have been done in air tightness of car. In this paper, the full car model has been used to analyze the interior sound field in car, in order to simulate the actual condition accurately. Through the comparison between the analysis results and the experiment, there was a good agreement in full frequency hand. However, there was also a clear peak in 130 Hz that may cause roar; the reason was assumed to be sealing defects. After all the sealing defects were fixed, the sound pressure in the driver’s ear was measured again and compared to the results before. It was found that seal could reduce the sound pressure, which also means the sealing performance of car must be maximized when manufacturing. The contribution coefficient of each panel towards the sound pressure in the driver’s ear in 130 Hz has been calculated by using ATV method in this paper; the result showed that the top panel of car was the main reason for the existence of the clear peak in 130 Hz. Through the replacement of original interior decoration with compound sound package structure and the change of each layer’s properties, the sound package structure with the minimum transmission sound power has been found. The results showed that the combination of (3-4-1) sound package structure is optimal (which means the damping layer thickness was 3 mm, the porous material layer thickness was 4 mm and the viscoelastic cover layer thickness was 1 mm). Besides, the combination of the damping layer with new material has shown a better acoustic performance. This scheme has been used in the top panel of car and has apparently improved the sound pressure condition in the driver’s ear.