Planning of Room Acoustics

Planning for good room acoustics begins with an inventory of the demands of activities and the pre-conditions of the project. This provides data of the room’s size and shape. The right shape, together with the material desired in the room, is important to obtaining the right acoustics. An incorrect shape and volume creates great limitations that, among other things, result in the need to use much more sound-absorbent material to damp defects in the room.

Impressions and Function

Among the characteristics we look at in order for the auditory impressions to be right are the tone of the room, the diffusion of sound via reflections, the sound’s angle of incidence toward all spectator positions, the amount of early reflections and timbre.

Correctly designed, the room attains good clarity and the right tone and room atmosphere for its purpose. Auditory impressions should also match visual impressions.

The room needs to work not only for the spectators. Speakers, musicians and actors on the stage need also to be given the impression that they sound right. In conference rooms and rooms for debates, the room should provide for sound propagation between all participants.

Three Scales

These characteristics and many more are obtained using shape, volume and materials. Planning must be done in at least three different scales, since the wavelength of audible sound varies from several metres to a few centimetres. In practical terms, this means that the shape of the room governs the low frequencies, the bass.
Wall panels, landings and ceiling directions govern the middle register and the surface structure of all surfaces affects the treble. Furnishings also have great effect.

Freedom from Disturbance

Yet another important factor in the planning of rooms is freedom from disturbance. Rooms must be quiet. Disturbances from the surroundings or from the building’s installations must not be so strong that they disturb activities.

Requirements must be correctly stated so that the ventilation plant can be dimensioned so as not to cause low-frequency disturbance. If you are sitting next to apparatus, this is a very important consideration, for which normal CAD programs do not have the right answers.