An acoustic law named after Berger (doctoral thesis 1911). Acc. to this law, in case of perpendicular incidence of the sound waves, the sound insulation effect of a wall increases by 6 dB with each doubling of the wall's mass or of the sound's frequency.

Depending on the basic material used, artificial fiber materials are called rock wool, glass wool or slag fiber. The main function of these materials is thermal insulation, but they can also be used for the absorption of air-borne noise and for impact noise insulation (e.g. footsteps). As they can release fibers, mineral wool materials are suspected of presenting a health risk during processing and installation.