The magnitude of the impedance discontinuity is crucial
In structure-borne noise insulation, it is important to minimize as far as possible the conversion of vibrations into audible sound transmission by means of vibration protection.
Structure-borne noise insulation is a special type of vibration isolation or vibration decoupling. Structure-borne vibrations spread wave-like within a machine or machinery and excite components to vibrate. These mechanical vibrations are then audible as sound transmitted in the form of sound waves (secondary airborne noise). Such sound transmissions are reflected by boundaries of various materials.
The degree of reflection, and thus the effectiveness of the structure-borne noise insulation, is dependent on the magnitude of the impedance discontinuity. Impedance discontinuity is the difference between the elasticity and the density of different materials.