Acoustic. Vibration Decoupling
Noise is transmitted through solid surfaces by vibration. When one solid vibrating surface is in physical contact with another surface it causes the second surface to vibrate too. In the form of vibrations, noise can easily travel from machinery along pipes and through walls.
Vibration decoupling is the process of introducing flexible, visco-elastic, materials between two solid surfaces. As the first surface vibrates the decoupling material can compress against the second solid surface - effectively stopping the vibration from passing through.