Energy decay in acoustically coupled spaces

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

Many of the conclusions that are used in the world of auditoriums can be transferred to recording studios, rehearsal rooms,… Let’s say, for example, that we want to set up a recording room in a place that does not have much floor space. , but on the other hand it has a lot of height. A possible design would be the construction of two spaces coupled one above the other, with an opening studied so that the exchange of sound energy between them is adequate. If the lower volume has several absorbing surfaces and the upper one is highly reflective and diffuse, we will achieve a sensation of double slope in the energy decay with many possibilities within the world of recording. Even a variable aperture can add more versatility to this system.

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