A case of particular interest in the study of architectural acoustics is coupled spaces. A coupled space can be defined as a main volume connected through one or more openings to a second space with a lower volume. When a sound source is placed in the main volume, the sound energy trapped in the coupled room, returns with a delay. The delay in the arrival of the sound energy coming from the coupled space produces double sloped energy decay, not typical in conventional volumes. This phenomenon has been used in many auditoriums that have incorporated reflective chambers, coupled to the main volume to have some flexibility in variable acoustics. The presence of multiple energy decays can produce a different impact on the quality of the perception of room acoustics.

Many of the conclusions that are used in the world of concert halls can be imported to recording studios world ... For example: we’d like to build a recording room in a location that does not allow us enough surface to get a big volumed room, but a big height is available. One possible design would be the construction of two coupled spaces on top of another, coupled with an opening allowing the sound energy exchange between them. If the lower volume has some absorbent surfaces and top space is very reflective and diffuse, we’ll get a feeling of smooth reverberation time with many possibilities when recording. Even a variable opening can add more versatility to this idea.

References

 Bradley, D. T. and Wang, L. M. (2005). “The effects of simple coupled volume geometry on the objective and subjective results from nonexponential decay.” J. Acoust. Soc. Am., 118, 1480-1490.

Bradley, D. T. and Wang, L. M. (2006). “Room Acoustics in Coupled Volume Spaces” Architectural Engineering . University of Nebraska - Lincoln