The architectural form for the ecumenical White Chapel, serving the students and faculty of the Rose Hulman Institute of Technology, is both simple and dramatic – a series of gothic arches that grow gradually larger as they march down the nave. The result is a sort of A-frame crossed with a horn of plenty. The platform is at the large end of the horn, backed by a glass curtain wall overlooking a lake. The small end of the horn, behind the congregational seating, has a rough stone wall that ensures a diffuse acoustic return to musicians or speakers on the platform.
During design, ray-tracing indicated focused double-bounce echoes off the concave ceiling/wall surfaces. To prevent this focusing, the gypsum board ceiling was changed to longitudinal bows made of glass-fiber reinforced plaster. To provide more complex diffusion and cleaner lateral reflections, a 5’ vertical wainscot was introduced. Periodic vertical bands of glass in the ceiling/walls remained, but they are narrow enough that the flare of the room’s footprint naturally prevents undiffused double-bounce reflections off the glass.
The bows at the ceiling/wall surfaces were originally designed as 2” plaster for bass support. After they were value-engineered to glass fiber reinforced gypsum (GFRG), glass fiber batt was added behind the panels to damp them. The sound is pleasant, and appropriate for contemporary forms of music.
The floor is covered in thin carpet, the only fixed absorption in the room. The loose chairs are upholstered to minimize the acoustic change between lightly occupied and fully occupied conditions.
Air supply is from floor grilles along the side walls. The room is narrow enough that low velocity supply in these locations provides adequate comfort while maintaining an RC-22 background noise level. Mechanical equipment is located in a low wing that also contains restrooms and support spaces. The short duct runs and the inability to line buried ductwork did result in a small increase in mechanical noise at 250 Hz.
The room has a pleasantly live ambiance, well suited to a variety of musical types. Congregational singing is well supported. Natural speech carries well in the room, but a simple audio system has also been provided. The system relies on two pairs of small cabinets mounted to the side walls – one pair flanking the platform and one pair at mid-house. An electronic organ and a grand piano fill the room beautifully.