Hard, reflecting materials are bad sound absorbers. Examples of such materials are metal, gypsum board or chipboard. Due to their physical design and density they reflect sound and are unable to absorb it. So called "soft" materials are far better suited. They absorb sound and change it into another form of energy.

The result is the damping of sound to the right level. To achieve this it must be noted that the absorbing material must have a certain thickness, or that the reverse side (e.g. ceiling cavity) has depth. This is of great advantage when sound absorption of low frequencies is to be achieved. This means when planning and building open office spaces they should be equipped with sound absorbing acoustic ceilings or wall panels with a thickness of at least 40 mm.
 

As already mentioned, a hollow cavity behind acoustic material should be planned for. To obtain the optimal acoustic for an office floor, a relatively big area of absorbing materials is needed.

Seen from an architectural point of view the ceiling offers the most potential. It is therefore obvious to recommend that the ceilings in acoustically sensitive open space areas be covered completely with absorbing materials. Should enough wall areas be available for acoustic paneling, then these may also be used. It should be noted when paneling two walls not to use directly opposite lying walls but adjoining ones.

This will avoid the so-called "ping-pong effect". The use of sound absorbing material in the areas along the edges where the ceiling and wall meet is extremely effective because any sound not absorbed there is reflected back into the room.