Sound insulation capsules and casings stop sound propagation directly at source. Working with capsuled machines decreases the exposure to noise significantly. The efficiency of the capsule depends particularly on the sound insulation (density) of the capsule wall, the capsule's decoupling from the noise source and on the absorption coefficient of the soundabsorbing lining of the capsule.
A noise source inside a casing gets increased by reflections on the capsule wall. To avoid the emission of this increased noise through the capsule vents (for material transfer, ventilation etc.), the inside of the capsule needs to be faced with soundabsorbing material. It is important, that the chosen material fits the frequency range of the noise source. The sound insulation of the capsule is only as good as the applied absorber.