AES Section Meeting Reports

Indiana University - September 19, 2013

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The Indiana Chapter of the AES gathered in the auditorium at Sweetwater sound in Fort Wayne Indiana the evening of September 19th where we enjoyed a talk on studio acoustics presented by Russ Berger, principal of the Russ Berger Design Group. A contingent of Audio students from St Francis College swelled our ranks to 47 attendees. Mr. Berger presented some wonderful looking examples of his work and taught some of the principles of design.
He explained that any performance space must have sufficient volume to allow the expected instruments to "bloom" or allow the audio to develop fully within the performance space. He also strongly suggested that bass traps should be placed opposite the location of the bass source; if the subs are on the front floor then the trap should be toward the back ceiling. "Garage" Studios should be totally independent of the adjacent house and must include amenities such as restroom facilities. This keeps peace within the family relationship. Studios must reflect the budget of the individual sponsoring the space, it can and will result in acoustical compromises. Each compromise must be made known to the owner and agreed upon prior to construction. If agreement cannot be made then the designer must know when to walk away. Avoid side wall diffusion as it will smear the arriving front signal. The control room rear wall needs to be placed with respect to the operator so that reflections from that wall will be around 15 to 20ms behind the signal from the front loudspeakers. This allows the operator to resolve between the direct signal and the reflection. The control room MUST not affect the acoustical signal, if it does that coloration will not follow into another listening environment thus compromising the sound and erasing the effort made to create it. The smaller the room the more pronounced the mid band resonances will be. When designing a floating floor pick a resonant frequency for that floor which is below the frequency of interest, if not it may amplify rather than eliminate the interference. And finally "Nothing looks so much like a new phenomenon as a mistake!"
Mr. Berger also recommended two books "Sound Reproduction: The Acoustics and Psychoacoustics of Loudspeakers and Rooms" by Floyd Toole and "Music, Physics and Engineering" by Harry F. Olson.
In conclusion a question was asked concerning what metrics were used when he evaluated a completed space. First of all back ground noise, a space should not be quieter than an NC25 as any quieter will allow noises within the space to become a distraction. Second, does the room sound natural when speaking in it and the last criteria mentioned was air velocity and turbulence. Temperature layers or stratification can cause significant acoustical path changes as the sound changes velocity while passing through different temperature layers.
It is with deep appreciation we thank Mr. Berger for taking time from his schedule to share some of what he has learned. All present took some new knowledge with them whether student or crusty member.

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AES - Audio Engineering Society