By Noral D. Stewart (Copyright 2019)

Spaces intended for dining and social conversation (restaurants, fellowship halls, cafeterias) should make it easy for people to talk to one another comfortably. This becomes very difficult with many people talking at once as the room becomes very loud. Some control can be achieved with careful design. The most important factors in these situations are the loudness of the room and the ratio of the loudness of the person one wants to hear to that general room loudness, called the signal to noise ratio.

The room loudness is primarily dependent on the ratio of the amount of sound absorption in the room to the number of people talking at any one time. The more absorption and the few people talking, the quieter it is. When rooms are very crowded with small floor area per person, it is extremely difficult to get adequate sound absorption in the room. In most cases the ceiling should be very highly absorption over almost the entire area. Absorption on walls can help also. Carpet can help reduce the amount of other absorption needed, but carpet alone will not be sufficient. Where possible, sizing of tables to encourage conversation groups of 4 to 5 people helps reduce the number of people talking at once.

The signal to noise ratio is dependent on this loudness, always becoming worse as loudness increases, but also on the separation distance between the talker and intended listeners. Smaller tables that put people closer together help greatly.

If the room will also be used for public speaking where a single talker is addressing the whole room, then the reverberation time becomes important. This is controlled by the ratio of the amount of sound absorption to the room volume. The dimensions and occupancy of the room will dictate whether the loudness control or reverberation set the required sound absorption for the room.

The information in this document is not provided as a consulting service or as a solution to any specific problem.