The sound pressure level in a room is determined by the sound source and by reflections of the walls, floor and ceiling. Sometimes, these reflections are desired, e.g. to achieve a sufficient speech intelligibility at a greater distance; sometimes these reflections are undesirable because it creates an annoying high sound pressure level or privacy is being disturbed. Depending on the use of the room advice is given in order to realize appropriate room acoustics for the specific room. This is not only applicable to, for example, offices or meeting rooms, but also to, for example, shopping malls and atria. In theaters and concert halls, the acoustics is of primary importance, we speak of room acoustics. Specific room acoustic problems occur in open plan offices and so-called innovative offices where a sufficient sound reduction by distance is required, but the sound pressure level must be sufficiently high too.