Vehicle noise is mainly divided into exterior and interior noise. The noise outside the car includes the noise of the engine, the noise of tire and road friction, and the wind noise generated by the resonance of the car surface and the air friction during the driving process. In vehicle noise mainly refers to the noise from the car outside the car that is transmitted to the car through multiple channels and the noise transmitted to the car by the structural vibration of the body parts excited by the transmission path of various parts of the car during vibration. The sound waves of these noises are due to the interior space. Under the influence of the acoustic characteristics, a complex reverberation sound field will be formed, and finally the noise in the car will be formed.

Factors affecting the sound absorbing effect of sound absorption materials in automotive interiors

    · The flow resistance of the material

Automotive Fibrous Sound absorption material is a porous material. When sound waves cause vibration in the air, the physical parameters of the sound absorption material's air permeability will allow a small amount of air to pass through the pores of the porous material. At this time, the static pressure difference between the two sides of the material and the linear velocity of the air flow the ratio between is the flow resistance of the material. Factors such as the number, size and degree of interconnection of the internal pores of the attracting material will affect the size of the flow resistance, and the size of the flow resistance has an important impact on the sound absorption effect of the material. A certain thickness of the porous material should correspond to a reasonable flow resistance value. Too high or too low will affect the sound absorption performance of the material. Therefore, it is necessary to adjust the flow resistance of the material, control the flow resistance value within the scientific range, and play its maximum role.

    · The influence of material thickness

The thickness of the same porous fibrous sound absorption material is constant, the sound absorption coefficient is relatively low in the low frequency range, and the sound absorption coefficient increases rapidly with the increase of the frequency, and the change of the sound absorption coefficient is not obvious when it reaches the high frequency range. However, as the thickness of the material continues to increase, the high frequency noise absorption effect does not increase significantly, while the increase in thickness has a greater impact on the low-frequency sound absorption coefficient.

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