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Letter From the Director

Welcome to the new Acoustical Research Center (ARC) at RPG Acoustical Systems, LLC

In 1983, RPG Diffusor Systems introduced the first commercial reflection phase grating diffusers and pioneered the development of the modern sound diffusion industry. RPG Diffusor System’s mission: to continually develop innovative acoustic technology through a commitment to fundamental acoustics research. After founding RPG Diffusor Systems and designing a range of sound diffusers, the challenge was experimentally documenting their performance. In 1984, not having access to an anechoic chamber, we developed the first ground plane goniometer in a reverberant space. Using this goniometer and a TEF analyzer, we began an intensive measurement program to characterize these diffusers at full scale in large spaces, including a sports arena, a motion picture sound stage, and a local high school gymnasium. In 1990, RPG Diffusor Systems funded the DIrectional Scattering Coefficient (DISC) project to devise a standard methodology for evaluating diffuser quality. In 1991, the Audio Engineering Society invited me to chair the SC-04-02 standards committee to develop a diffusion coefficient using the DISC project. In 1993, the Journal of the Acoustical Society of America asked me to referee a paper entitled “Optimization of Profiled Diffusers” by a recent graduate of Salford University named Trevor Cox. To properly review the paper, we created a Boundary Element Method program to compare with the predictions in the paper and the first scale model, boundary measurement goniometer, to validate the predictions experimentally. Both the paper and the review were published in 1995. Realizing that good acoustical design results from an appropriate combination of absorptive, reflective and diffusive surfaces, we also began developing absorption technologies, including hybrid diffusive/absorptive systems and dedicated low-frequency absorbers.

 

To experimentally measure the random incidence absorption coefficient between 100 Hz and 5,000 Hz, we created a small 75 m3 reverberation chamber and a 7-ton, 24’ long, 2’x2’ concrete and steel impedance tube to measure the complex impedance of dedicated low-frequency absorbers between 20 Hz- 200 Hz. In 1995, in collaboration with Trevor Cox and Jamie Angus, we developed the first amplitude gratings and modulated phase gratings. Also, in 1995, I joined the ISO working group WG25 to develop a scattering coefficient, standardized as ISO 17497-1, in 2004. In 1996, to further the development of the diffusion coefficient, RPG co-funded a three-year research grant with the Engineering and Physical Sciences Research Council of the UK. Trevor Cox, Yiu Wai Lam and I were investigators, and Tristan Hargreaves was the doctoral student. This research was very fruitful because it produced the first 3-dimensional goniometer in an anechoic chamber and yielded the first robust diffusion coefficient described in the AES-4id-2001 information document and standardized as ISO 17497-2 in 2012. This diffusion coefficient has since been used as a metric to develop a range of new diffusing surfaces, including the first optimized welled diffusers, profile diffusers, 1D and 2D curved diffusers, baffled diffusers, genetic binary hybrid surfaces, flat and curved binary amplitude gratings, fractal and aperiodically modulated surfaces.

In 2017, a new entity known as RPG Acoustical Systems, LLC was established to go forward with the production and sale of a full line of absorption, reflection and diffusion products at our facility in Passaic, NJ. Together with this new team, we developed and built an Acoustical Research Center (ARC) to continue our innovative research. Using the experience from our formative years, the ARC was equipped with an Experimental Research Lab containing a 285 m3 rev room, a new ground plane goniometer and the original upgraded low-frequency impedance tube; a Virtual Simulation Lab, with an advanced cloud-based software version of our early BEM program, called VIRGO, to virtually simulate the 2D ground plane and 3D goniometer measurements; and a Virtual Education Lab that generates weekly LinkedIn posts to share our four decades of research. RPG Acoustical Systems, LLC continues to share its research with the acoustical community through publications in peer review journals, conference proceedings, lectures, and three editions of my book with Professor Trevor Cox, entitled “Acoustic Absorbers and Diffusers: Theory, Design and Application, 3rd Ed, CRC Press 2017. I have also contributed several chapters to the Master Handbook of Acoustics, 6th Edition, published by McGraw Hill Professional 2015 and a book that reflects the life, work, and legacy of one of the greatest acousticians of the 20th century entitled “Acoustics, Information, and Communication: Memorial Volume in Honor of Manfred R. Schroeder,” published by Springer and edited by Ning Xiang and Gerhard M. Sessler (2015). A complete list of publications can be found on Google Scholar. We also created the ARC Associates Alliance to further share our research and the ARC facility with the architectural acoustics community. This is just the beginning…

Dr. Peter D’Antonio

Director of Research

Acoustical Research Center

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