Edwina Palmer Hall
Hitchin, England

ACOUSTICIAN
“Research by Cox and D’Antionio 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 and this can be tailored to provide 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 from 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 Waveform is shown (inset above). The final installation satisfied the architect’s design intentions, as well as meeting the acoustician’s requirement to neutralize focusing and provide diffusion. It can be seen from the photo that the wall steps back at a 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. 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.”

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