First Publication of Autocorrelation Diffusion Coefficients From Far-Field Measurements
"Surface diffusion coefficients for room acoustics: Free-field measures", Hargreaves, T.J., Cox, T.J., Lam, Y.W., Dantonio, P., The Journal of the Acoustical Society of America, 2000, Vol.108, No.4, pp.1710-1720.
This is the first publication of the work which was funded by the Engineering and Physical Research Council (UK), with support from RPG Diffusor Systems, Inc. Visit the RPG Research section for additional information.

The surface diffusion conefficients is needed in room acoustics to enable the quality of diffusing surfaces to be evaluated. It may also facilitate more accurate geometric room acoustic models. This paper concentrates on diffusion coefficients derived from free-field polar responses. An extensive set of two- and three-dimensional measurements and predictions was used to test the worth of different diffusion coefficient definitions. The merits and problems associated with these types of coefficients are discussed and past parameters reviewed. Two new coefficients are described. The new measure based on the autocorrelation function is forwarded as the best free-field coefficient. The strengths and weaknesses of the coefficient are defined.

New Home Theater Design Guide
We can summarize the potential acoustical distortion problems and possible solutions by dividing the frequency range roughly at 300 Hz. Below 300 Hz we need to focus on the interference at the listening position between the loudspeakers and their adjacent boundaries, as well as the coupling between the loudspeakers and listener with the modal response of the room. These low frequency forms of Acoustical Distortion can be addressed with proper placement of loudspeakers and listening position, as well as the application of dedicated low-frequency absorbers in appropriate locations and low-frequency equalization. Above 300 Hz we are dealing with specular reflection effects which result in comb filtering and the lack of adequate sound diffusion. Comb filtering can be minimized through the strategic application of absorptive, diffusive, abffusive or diffsorptive surface treatment. Sparse diffusion can be improved through the application of efficient diffusive surfaces and a coupling of reflective and diffusive surfaces strategically placed.

Listen to the Music, Not the Room!
Since the founding of RPG in 1983, we have attempted to document the complex electro-acoustic interaction occurring in listening rooms, via journal publications, magazine articles and seminars. However, at the end of the day, hearing is believing. Therefore, we thought we would try to create Acoustic Demonstrations to illustrate the effect the room can have on what we hear. There is certainly a need for scientific audiology / test demonstration discs, but in this case we wanted to create demos that were both enjoyable to listen to and also informative, not a series of test tones.

Foundations of Engineering Acoustics
Frank J. Fahy's, of the Institute of Sound and Vibration Research, University of Southampton, UK, new book has some references to RPG Foundations of Engineering Acoustics presents a comprehensive exposition of the fundamental elements of audio-frequency sound and vibration, with emphasis on those which relate to noise generation by machinery, vehicles and industrial plant, and to the practice of noise control engineering. Many other examples of applications are also included: building acoustics, audio-engineering, underwater acoustics and musical acoustics.

It is written principally for undergraduates and junior postgraduates who wish to study acoustics and associated vibrational phenomena in relation to engineering products, systems, operations and processes; that is to say, engineering acoustics. The book will also be of great value to researchers and professionals as a reference text. For more information please visit the Academic Press Acoustics and Vibrations Web site.

Key Features:

Provides a 'cook book' of demonstrations and laboratory-based experiments for teachers

Architectural Acoustics, Principles and Design, by Mehta, Johnson and Rocafort, 1999
This book is a recent update to applied acoustics in the building environment. Madan Mehta and Jorge Rocafort are professors at the University of Texas at Arlington and the University of Puerto Rico, San Juan, respectively. Jim Johnson is an acoustical consultant with WJHW, Inc. in Dallas, Texas. This is a well illustrated, not-too-technical 400+ page volume which covers the basics with worked examples for many of the acoustical situations which architects encounter every day. The book is divided into a sequence which would support a course for architecture students, as well as having a wealth of information for architects and consultants. It starts with simplified physics of sound, hearing and human response and moves into reflection, diffusions, absorption and sound transmission. This leads into transmission loss of common constructions, impact noise isolation and noise control in buildings. The rest of the book is given over to behavior of sound in rooms, design of rooms for particular uses, mechanical vibration isolation and an introduction to sound reinforcement systems. There are 11 Appendix headings, including use of SI units, quadratic residue diffuser design, sight line calculation, sound absorption,transmission loss and impact isolation class data tables, and useful formulas. The book has been adopted by Neil Thompson Shade, Lily Wang and Bob Coffeen as their architectural acoustics textbooks. Copies are available for purchase online.

Announcing the Master Handbook of Acoustics, Fourth Edition
F. Alton Everest is a legend in the world of sound. The creator of numerous technical innovations, and the author of scores of books and scholarly papers, he has been a leader in television engineering, sound recording, motion pictures, radio, and multimedia. A co-founder and director of the Science Film Production division of the Moody Institute of Science, he was also a section chief of the Subsea Sound Research section of the University of California. An educator who has taught at several leading institutions for nearly 30 years. Having touched many of the technical highlights of the 20th century, he celebrated his 90th birthday in 1999. He and his wife live in Santa Barbara, California.

F. Alton Everest can take pride in the fact that his books have helped educate a generation of music enthusiasts. RPG has been proud to offer whatever research and product information requested in previous editions. In his latest offering, he asked Dr. D'Antonio to contribute three chapters to help provide current information for the next generation. These include Acoustical Distortion, Room Optimizer and Desktop Auralization. Dr. D'Antonio indicated that "Alton has been a friend and collaborator for many years and he has done this industry a great service. This last edition is significantly expanded and offers a view of acoustics from the past to the future. We wish Alton and Bonnie Gail good health and happiness". You can purchase the 592 page paperback online.

Topakustik and Topperfo Samples Now Available
A new sample box including several Topakustik and Topperfo samples is now available. As RPG expands its architectural acoustic surface finish products it is attempting to provide more samples for architects, interior decorators and acousticians. This new sample box measuring 12 7/8"x 9 1/8" x 4 7/8"contains trays of varying depth for a wide variety of samples. Specifying professionals are welcome to free samples of this new and extensive architectural acoustic system.

Dr. Peter D'Antonio Fellowship Announcement
RPG President/CEO Dr. Peter D'Antonio has been elected a Fellow of the Acoustical Society of America. Announcement of the election and presentation of the Fellowship certificate will be made during the plenary session at the Newport Beach, California meeting of the Acoustical Society of America December 4-8, 2000. The citation reads "For contributions to the applications of sound diffusion from architectural surfaces". We invite you all to attend.

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.

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.