Page 14 - Winter 2010

Fig. 6. Final result of absorption test.
neath the panels, I thought the opening location would prob- ably work.
The WoodWave© panel design is shown in Fig. 4. StructureCraft lined the inside of the vees with a black cloth and 2.5 inch thick mineral wool that helped meet the fire code requirements. The 2x4s surfaces are positioned and held in place by means of plywood bulkheads. These also support the sprinkler pipes and give the panels their shape. The panels are formed in a curve, much like an archer’s bow. A steel cable bowstring added additional structural strength.
The panels were constructed in StructureCraft’s shop. The process is shown in Fig. 5 with the black cloth in place. The interior plywood bulkheads are notched to secure the 2x4s in their proper locations. Conduit for the lighting is also placed in the hollow panels.
Because of the added area provided by the saw tooth sur- face, I predicted an NRC of about 1.2 and suggested that they mock up a sample and have it tested. In early 2006 a sample was built and sent to the Western Electro-Acoustic Laboratories (WEAL) in Los Angeles. The first test yielded an NRC of about 0.85, much less than I had calculated. At the time I was quite puzzled by the result. The reason, as it turned out, was that the absorptive material had not been properly secured and was jostled during the transport from Vancouver. It had fallen to the bottom (roof side) of the test sample. Since there was a black cloth between the wood and the mineral wool, this displacement could not be seen from the outside.
Fig. 7. Main Hall and rink with skaters (Photo by Stephanie Tracey www.photographywest.ca Courtesy Wood WORKS! BC).
10 Acoustics Today, January 2010