There are two ways of sandwich structure: one is to add anti vibration material between the steel plate and the steel plate; the other is to stick resin layer or asphalt based anti vibration plate on the steel plate. Appropriate elastic elements and damping elements are installed between the cab and the chassis to reduce the vibration of the cab structure and the secondary noise.

　　01 sound insulation

　　In order to prevent the engine noise from passing through, the sound insulation material is mainly used on the inner panel near the engine side of the cab. The holes of the hose, wire and steering column passing through the cab should be sealed to prevent the holes from transmitting sound.

　　Noise reduction of construction machinery cab

　　The running noise of the road surface and the noise of the engine exhaust device are mainly delivered through the bottom of the cab. Therefore, the double floor structure should be adopted on the bottom plate, the middle air layer acts as spring, and the sound insulation ability decreases.

　　02 sound absorption

　　Sound absorption is the use of materials and structures that can absorb sound energy to absorb part of the sound energy in the noise transmission path, so as to reduce the noise transmitted to the operator. For engine noise, glass fiber, blanket and foam sound absorbing materials are added to the enclosure near the engine side and the inner side of the hood, and the sound absorption intensity and characteristics are adjusted according to the thickness and density of the material.

　　Noise reduction of construction machinery cab

　　The interior materials of other interior surfaces of the cab should have sound absorption characteristics while considering aesthetics and sound insulation. Sound absorbing materials are mostly porous materials, such as glass fiber, foam plastics, blankets and so on.

　　The above three noise reduction methods are commonly used by manufacturers, which are feasible and fully meet the requirements of indoor noise and radiated noise required by EU CE directive.