Different types of room will create such different sound fields that this in itself requires different descriptors if a meaningful evaluation is to be made. The list of actual types of rooms can of course be made very long but, if we restrict ourselves to the most common ones, three different basic acoustic types can be identified.
The first is a room with little sound absorption, a “hard room” in which the surfaces reflect most of the noise.
Rooms with absorbent ceilings
Another type of room which is much more common is a room with a sound-absorbing ceiling. This type acts differently than the hard room and, as a rule, requires several descriptors for an acoustic assessment.
A third type is a room with extended forms such as open-plan areas and corridors.