"New Sound Diffusors in Practice", R.J. Orlowski, Arup Acoustics, Cambridge, UK, Acoustics Bulletin, Volume 25, No. 5, pp. 21-22 (September-October 2000).

"We are all aware that the heavy ornamentation in nineteenth century concert halls gives rise to a high degree of sound diffusion and that this is evidently beneficial for providing good acoustic quality. The reduction of ornamentation in twentieth century architecture has led to other geometries and devices being used to provide diffusion. Schroeder proposed diffusors based on mathematical number theory sequences. While useful, these QRDs® may not be universally acceptable aesthetically. Research by Cox, latterly in collaboration with D'Antonio, has resulted in accurate prediction methods for scattering from diffusers based on boundary element methods. This has enabled diffuser design to break out of the mould of Schroeder's number theoretic diffusers to provide a much greater range of stepped and curved diffusers. Using numerical optimization techniques and prediction methods , an architect or designer can select a desired shape or motif and this can be tailored to provide a diffuser with the required diffusion. This technique has been applied by Arup Acoustics to the design of a new rehearsal hall, the Edwina Palmer Hall , for the Benslow Music Trust, which provides residential music courses. For architectural reasons, a concave form was developed for the hall, which obviously gave rise to concerns about focusing. Curve-shape optimization was used to minimize focusing by the concave wall using a geometrical motif based on an amplitude modulated wave. "

The conceptual amplitude modulated rendering of the OptiCurve™ is shown in the Products section at the lower right of Diffuse Reflections Vol. 3 Issue 2. Two actual installation photos are shown above. "The optimized "wiggly" wall satisfied the architect's design intentions as well as meeting the acoustician's requirement to neutralize focusing and provide diffusion. The wall was formed from 25 mm thick medium density fiberboard (MDF) with a paint finish although glass reinforced gypsum (GRG) was considered as an alternative material. It can be seen from the photo that the wall steps back at high level. Also, thin vertical strips have been added to the curved surface. Both of these changes to the optimized curve were implemented by the architect to enhance the visual aspects of the wall in the context of the overall space. Neither is considered to have a significant effect on the overall scattering performance of the wall. Subjective listening tests to piano and clarinet music in the hall indicated a very uniform sound field with no evidence of focusing. Furthermore, both instruments produced an expansive sound with a very good balance between clarity and reverberance. Musicians found the hall easy to play in. The success of the Benslow project has led Arup Acoustics to consider curve optimization for providing diffusion for other projects, including a rehearsal hall with curvature in two dimensions."