As regards acoustic design, it is an advantage if different designs and procedures can be evaluated objectively. For this purpose, a number of measurable room acoustic descriptors have been defined. These descriptors can be used to formulate room acoustic specifications and to check the effect of different procedures. It would, of course, have been an advantage to have only one descriptor that works in all rooms. But hearing is multidimensional, so several descriptors are required.
Reverberance is linked to the speed at which sound energy disappears in a room. An unfurnished room with hard surfaces, such as a church, is perceived as being more reverberant than a well-furnished living room.
Speech clarity concerns the quality of speech transfer to the listeners. In a reverberant room with disturbing background noise, it can be difficult to pick up speech.
Auditory strength is the level at which we experience sound. A reverberant room gives a higher sound level than a room with added sound absorption.
The sound level decreases as the distance from the sound source increases. The design of the room (shape, furnishing, surface finish etc.) influences the extent to which the sound level decreases along with the distance.