Coupled Volumes: Aperture Size and the Double-Sloped Decay of Concert Halls

Abstract

The coupled-volume concert hall and its signature double-sloped sound decay attempt to reconcile the often-competing qualities of clarity and reverberance. By wrapping a room with another more reverberant room, and allowing for apertures to control the sonic transparency between the two rooms, designers use coupling to provide a sound field that is variable, longer, distinct, and performance-piece-specific. For this study a coupled-volume concert hall (based on an existing hall) is conceived with a fixed geometric volume, form, and materiality. Aperture size is established as variable. The simulated hall undergoes statistical and geometric (ray tracing software) analysis. Results show disparity in the absolute decay patterns projected by the two methods; however, both statistical and geometric relative analyses suggest a highly sensitive relationship between the aperture size exposing the coupled-volume and the double-sloped condition. To test the model, simulations are compared to real-room measurements taken in a coupled volume concert hall.