May 16, 2008
| by Dennis Burger
“What are the most important things that the average consumer can do to improve the acoustics of a budget-conscious home theater or media room?” That’s the question I ask Anthony Grimani, president of both Performance Media Industries, Ltd., and MSR Acoustics. I ask because Grimani’s storied history with Dolby Laboratories and THX, as well as his own consulting and manufacturing companies, have made him one of the world’s most respected names in the field of acoustics and theater design. Or, I should say, that’s why I pose the question to Grimani specifically; I ask in the first place because I’d like to improve the sound of my own mid-level media room, and quite frankly I cannot see spending $50,000 to $100,000 on acoustical treatments in a room with only $20,000 or so worth of gear.
“For someone who’s building a theater or media room from scratch,” Grimani says, “the first piece of advice I would give is this: ‘Spend only as much as you must to get reasonable gear.’ For some people that’s a million dollars, where others think a thousand dollars is enough. And I won’t state a price point, but the fact is that a good receiver doesn’t cost that much these days. Decent speakers don’t have to cost that much if you don’t need them to be super loud. Some people think you have to spend $5000 apiece on speakers before you can get good sound, and I simply don’t agree with that. I think you can spend less than that and keep the budget open for the rest of the system, which is the interface between the speaker and listener—the air in the room.” To get the most out of that air, Grimani offers three quick-and-dirty tips for better acoustics at any budget:
Silence is Golden
“First and foremost, you want to make sure that the room is quiet,” Grimani advises. “And that can either cost a lot of money or it can be really cheap. If you have a loud air conditioner in that room or a loud refrigerator nearby, I don’t care how good a piece of equipment you have in the room, the noise is going to rob you of fidelity.”
So much for replacing that end table with a mini-fridge—but like many of you, I’m sure, my media room is also home to my HVAC closet and air-return vents. In other words, the room can get kind of noisy. Or at least that used to be the case. By lining the inside of my HVAC closet door with acoustic-grade egg-crate foam, I was able to reduce the sonic impact of my running air conditioner on my room by nearly 8 decibels. I was also able to cut a few more decibels overall by carefully bending the slats on my air-return vents up a little to widen the gaps through which returning air travels. Time consuming? Yes. Expensive? No. And checking to see if the air zipping through your vents is causing a noise problem is exceedingly simple: just take the vents off and listen (or measure) for an appreciable difference.
If that hadn’t been enough to solve my air-conditioning noise problems (thankfully it was), there are any number of sound baffles and acoustic materials built specifically for HVAC systems and ducts, with budget ranges that run the gamut from Robin Hood to Robin Leach.
Test for Echo
“The second thing is to make sure you’ve controlled the total sound reflection content in the room, so that it’s not a big reverb chamber,” Grimani says. “And one thing to be careful of is the fact that your auditory system can listen around that, but in the process your brain is working overtime to get rid of the unwanted sound reflections. And so ultimately the only way to know if it’s right or wrong is to measure it.”
How does one go about getting rid of room reverb, though? “You need to soak up about 25% of the wall surface with something absorptive,” he says. “And that something can’t be a thin drape, because a thin drape doesn’t absorb very much. It needs to be some thick, absorptive materials; whether they’re purpose made or incidental, you need at least 25% of the surface covered with stuff.”
In addition to absorption, the right amount of diffusion is also critical to an acoustically balanced room. And again, diffusive materials can range from purpose-built panels that blend into (or even enhance) a room’s décor, to properly placed bookshelves with the books unevenly spaced.