Absorption

Absorption

When sound waves hit bodies that extract energy due to resonance or frictional losses, the term absorption is used. To absorb means as much as "to take up or swallow".
This means that through an absorber, in the best case, a large part of the sound energy is dissipated. How strongly the object absorbs the sound wave is indicated by the absorption coefficient alpha (α). This is a dimensionless quantity ranging from 0 to 1. The value 0 means that no absorption takes place (0% sound energy removal). 1 means that the sound wave is completely absorbed and no reflection takes place. (100% sound energy extraction).

Sound waves of different frequencies have inversely proportional different wavelengths. This means that the lower the frequency, the longer the wave. For example, a sound wave with a frequency of 50 Hz already has a wavelength of almost 7 meters under normal conditions. The nature of these extremely long waves often leads to problems such as room modes, and makes sound absorption and sound insulation more difficult.