Stig Ingamansson’s Noise Control:Principles and Practice

B5 – Sound from Vibrating Plates – Size and Thickness 

LIGHT OBJECTS AND LOW SPEED PRODUCE THE LEAST IMPACT NOISE 

When a plate is struck by an object, the plate vibrates and makes noise. The sound level is determined by the weight of the object and its striking speed. If the drop height of an object is reduced from 5 meters to 5 centimeters, or if the weight is reduced from 1000 g to 10 g, the sound level drops by about 20 dB. 

Principle 

B6 – Sound from Vibrating Plates – Size and Thickness 

A DAMPED SURFACE PRODUCES LESS SOUND 

As vibration moves across a plate, it gradually decreases as it travels, but, in most plates, this reduction is rather small. In such cases, the material is said to have low internal damping. Internal damping in steel, for example, is extremely poor. Good damping can be achieved by adding coatings or intermediate layers with better internal damping. 

Principle