Edwina Palmer Hall, Hitchin, England
"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."

Announcing BASWA®phon: The smooth, seamless acoustic plaster system
Acousticians have long sought an absorptive, smooth, seamless and durable plastered finish to satisfy the aesthetic requirements of architects and clients. RPG® is now offering a new patented field-applied system that provides exceptional absorption, a strikingly beautiful appearance, with integral coloring and cleaning possibilities. BASWA®phon offers a long awaited solution and is finding immediate application in architectural acoustics. Read More

RPG Announces new Room Sizer Software and Describes The Algorithm at AES Amsterdam
Modes in small rooms often lead to extended sound decays and uneven frequency responses. In critical listening spaces, this causes unwanted coloration effects that can be detrimental to the sound quality. The problem arises at low frequencies because of the relatively low modal density. Many designers try to overcome the problems of modes by choosing an appropriately proportioned room and by the use of bass absorbers. This paper is interested in the former, the choice of room dimensions to minimise the coloration effects of modes. The paper starts by discussing previous studies by others, which have suggested optimum room ratios or design methodologies. Then a new method is outlined - this is based on numerical optimisation - and the old and new methods are compared philosophically. Results in the form of modal responses are given to demonstrate the power of the new method. Read More

RPG Samples Now Available
To acquaint the architectural acoustics community with the growing array of new and innovative acoustic tools, RPG is offering many samples to professional specifiers. The box can contain an array of Topakustik, Topperfo, BAD panel and FlutterFree samples or samples of the new rigid or flexible BASWA®phon samples. Please request from your local rep or contact RPG.

Dr. D'Antonio Authors Continuing Article on Acoustical Distortion in Surround Professional
Surround Professional Magazine offers the professional audio community an authoritative source of information on all of the issues affecting the multichannel music surround sound. Dr. D'Antonio is contributing seralized articles on how acoustical distortion can affect the accuracy of what we hear in surround sound environments. Look for Part V, which deals with the benefits of optimal speaker and listener placement in critical listening rooms. For copies of past articles please contact www.surroundpro.com.

Diffuse Seminars
RPG offers regular educational seminars for acousticians, sound contractors, home theater system integrators, architects, and other specifying consultants to apprise the industry of our research, new products, application assistance, and an introduction to RPG's Room Sizer, Room Optimizer, Shape Optimizer, CATT Acoustics software and Lake Technology convolution platforms. The press is also welcome. RPG is applying for AIA Continuing Education credits. The response to these educational seminars has been very enthusiastic. The 2001 seminar calendar will be posted next month.

If you are interested in attending, please e-mail to info@rpginc.com, contact your local rep or call Jeff Angel at 301-249-0044.