If the Walls — and Ceilings — Could Talk

Studio Acoustics and Treatment Can Have a Strong Influence on Your Sound
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Studio Acoustics and Treatment Can Have a Strong Influence on Your Sound

Somewhere between the shower stall and an anechoic chamber.

Acoustically, that's what an air studio, production studio or voiceover booth should sound like. If you really do the job right, your listeners may be able to tell they are listening to your station by its sonic signature even if they don't know the announcer or aren't clued in by the content.

Sure, mics and processing play a part in that signature, but the sound of the studios also leave an impression. In the face of ever-narrowing ratings points, creating a unique identity becomes increasingly important, but there's more to it than that.

The key word is design. If you don't design, you get what you get and there's not a lot you can do.

Radio World talked to a designer and several companies that make acoustical treatment and offer support for its application. Here's what we heard.

(click thumbnail)An excellent sound-absorbing scheme — panels on the walls, corner traps and diffusion blocks on the ceiling.
What can a radio or voice studio planner expect to accomplish with ceiling tiles and foam?
According to designer Tony Grimani at MSR Inc. in Fairfax, Cal. (www.msr-inc.com), "If you're a station manager, work efficiency is important. You can get more from your staff with a good design. A room that has bad acoustics fatigues the ear and brain. In one project we did, the staff's comment was that in the acoustically engineered room they could now work eight hours or more without getting a headache."

Grimani says that where to put ceiling tiles and wall panels requires knowledge of acoustics and experience. "I've heard rooms 'designed' so badly that, if they were airplanes, they'd never get off the ground."

"Using the right amount of the right material in the right place," he said, "makes a big difference. There are a lot of different types of ceiling tiles and they come in different thicknesses. There are 1/2-inch pressed fiber materials that are about 50 percent absorptive. There's also dense fiberglass in 1-inch or 2-inch thicknesses. If you line a ceiling with that, the room will be too dead.

"Although the figures vary depending on the specific space or its use, 25 percent to 30 percent of the walls and ceiling need to be absorptive. For example, I like a combination of real fiberglass ceiling tiles along with a hard tile."

(click thumbnail)Effective sound panels can be quite stylish.What should they not expect to achieve?
Gavin Haverstick is lead acoustical engineer at Auralex Acoustics Inc. (www.auralex.com) in Indianapolis. He says when moving studios into a new space where you are not building from scratch, choosing the right room can be equally important as acoustical treatment.

"You cannot expect wall panels and ceiling tiles to completely solve extreme room geometry problems. You want to avoid choosing rooms with dimensions that are evenly divisible by each other. An 8 x 16 x 8 foot room is a good example of a bad room. A better option would be 7 feet x 15 feet x 8 feet."

Built-in or freestanding shelving for CD and other materials can act as diffusers to mitigate bad acoustics to some degree, but there's only so much that simple acoustical tricks can overcome in the face of bad room geometry. Haverstick says even adding splayed walls may or may not help.

"You need at least 10 degrees of combined angle between two opposing walls, however if angling the walls creates acute angles in the corners (less than 90 degrees), low-frequency issues can become more problematic."

What are common errors do users make?
Eric Johnson is in charge of East Coast sales for Pinta Acoustic, formerly Illbruck Acoustic, makers of Sonex. According to Johnson, "We see situations in which too much or too little absorption has been applied. For this application, I like 0.7 to 0.8 seconds of RT60 reverb (decay) time. A reverb time of 0.3 seconds is totally dead and too much. It makes the talent push harder, tires them out and strains their voices. As you get more than a second or so, intelligibility falls off because of early reflections. It's also fatiguing to listen to. Your listener may just get tired and tune out without even knowing why."

What special needs do radio broadcasters have?
According to Michael Binns, president of Acoustical Solutions in Richmond, Va. (www.acousticalsolutions.com), the needs of broadcasters basically are the same as other studio owners.

(click thumbnail)Heavy foam on the walls, acoustic ceiling, foam mini-gobo behind the mic and even acoustic treatment for the curtains. This room has it all.
"To work well, all studios need to be isolated and have the proper amount of acoustical treatment for the individual space to perform properly. Studios with a lot of cables need to think about pass-though conduit stuffed with acoustical putty. You remove the putty, run cables and then restuff the putty."

Binns says that how a studio is used can make a significant difference in the acoustical treatment. If you are recording live music from a studio, or mixing music in a studio, you would want the studio to be a little more live than a voiceover booth.

What tips can help users get better performance out of the products?
"This may sound a bit too basic and I'm not trying to sound insulting, but read and understand the specs of the materials you're buying."

That's according to Nick Colleran, co-owner of Acoustics First Corp. in Richmond, Va. (www.acousticsfirst.com).

"If they indicate you need 2 inches of a product for the wall, you can probably use just 1 inch if you put a 1 inch space between the panel and the wall. Angling wall or ceiling treatment will broaden the range of frequencies affected, but you need a very steep angle to deal with frequencies below 1000 Hertz. The wily low end takes a lot of cyphering."

Colleran says using tones and a spectrum analyzer to measure rooms is helpful; but for music rooms, how music sounds in those rooms is even more important. "The best solution is not always about how many sabines per square foot you have. Mood is also very important. If you put a window in and it makes the talent more comfortable, they'll perform better."

How should a user determine what thickness, shape and style to buy?
All of our expert respondents answered similarly. The exact pattern doesn't matter. Thickness is determined by the frequencies you are trying to control. Use 2-inch foam or 1-inch fiberglass for frequencies of 1 kHz and up.

For a normal listening room, budget to cover 25 percent of the ceiling and wall space. For a studio, 35 to 40 percent coverage. Spread the treatment evenly around the room. One-inch foam is useless below 500 Hz. Use at least 2 inches of fiberglass or rock wool, at least 3 to 4 inches of foam for low frequencies. The rest is aesthetics. Shape and style has more to do with budget and what you want to look at.

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