In Search Of The Audio Abode---The Hi-fi House
Most of us don't particularly enjoy moving. It's disruptive, nerve-wracking, and---no matter how "full-service" the moving company---physically exhausting. But, for the serious (read: manic) audiophile, relocating to a new home offers a side benefit denied ordinary folk: It's a golden opportunity to acquire a listening room that's a sonic asset rather than a liability.
Acoustically speaking, most audiophile listening rooms are abominable. This is because they were designed to be living rooms or bedrooms or family rooms or recreation rooms---any kind of rooms except listening rooms. Often of asymmetrical shape, they tend to have doorways where the speakers should be, windows where sound absorption is required, flexible walls that leak low bass to other rooms or to the great outdoors, dimensions that mess up the frequency response, and inadequate AC service. Yet most audiophiles, including serious high-end types, are blissfully complacent about their listening room. Because it "came with the house," there's a tendency to feel one is stuck with it, and that if it isn't up to snuff, there isn't much that can be done about it except for a certain amount of band-aiding with absorptive or diffractive wall treatments.
Moving to a new house is the time to start thinking seriously about your listening room, because the move can give you a clean slate, a new start, a new lease on your audio life, a chance to begin again your quest for the Holy Grail of perfect sound without the starting handicap of a lousy room. Here's a rundown of what to look for and what, in particular, to avoid, in order of importance.
If your listening room is subject to the constant intrusions of barking dogs, lawnmowers, rapid-transit buses, sirens, chain saws, jet planes, freight trains, and other people's stereos, you might just as well forget all about retrieval of low-level information from recordings. Obviously, if you're foolish enough to buy a house right under the approach path of O'Hare International Airport or next door to a sawmill, you'll deserve what you get. Almost as bad is a location within a half mile of a busy highway, particularly if it's a sloping-grade truck route or has a traffic light on it. (All vehicles make much more noise starting than driving.) But even if you avoid the obvious mistakes, there are things to look out for. Neighbors, for instance.
Neighbors are nice, up to a point. Socially, they can be charming, polite, friendly people. Privately, they are loutish, insensitive, inconsiderate sonsofbitches. All of them own dogs that bark incessantly, they're into heavy metal played at overload levels outdoors on a boombox, and they have an abiding hatred for any music written prior to or later than their ill-spent youth. They do not understand or appreciate audio, and cannot conceive of how you could listen to that kind of music that loudly and then complain about their noise.
If you can hear your neighbors, and they can hear your system, you are almost guaranteed an ongoing series of hassles that will not be resolved until you choose between headphones or homicide. Supposedly, what you do in the privacy of your home is your business, but that is true only as long as what you do there stays there. If you insist on listening with the windows open in nice weather, the noise you make will not stay in your home, and your neighbors' noises won't stay out. In this case, it will cost you a lot for your privacy, because the only thing that will buy it is distance.
Outdoors, sounds travel in all directions away from their source, like the skin of an expanding balloon. And, just as the wall of a balloon becomes thinner as it expands, the wavefront of a sound becomes weaker as it travels away from its source. Eventually a balloon will burst, but soundwaves just continue to expand until they dissipate into nothingness. This attrition occurs at a predictable rate: The sounds become 1/4 as strong---that is, their level diminishes by 12dB---every time they double their distance from the source (fig.1). [It actually becomes 1/2 as strong, a reduction of 6dB.---Ed..]
Fig.1 The effects of outdoor distance on sound-level attenuation and background SPL, for a 90dB source. The figures are approximate, depending on topology and ground cover.
If the sound-pressure level (spl) 10' outside your open window is 90dB, it will be 78dB at 20', 66dB at 40', and 54dB at 80' away. Now, an spl of 54dB is about the background level of an expensive restaurant (without music). This isn't all that loud, but a neighbor 80' from your open window will still hear your music quite loudly enough to know that he hates what you're listening to. You, on the other hand, will hear his lawnmower, his outdoor music, and his barking dog loudly enough to give serious competition to any musical pianissimo, let alone those subtle ambience cues and overtones. 80' of distance just ain't enough.
Just how much sound isolation do you need? The purist view might be that you can't have too much, but this doesn't mean you can't have more than you need or might care to pay for. An spl of 10dB---about the loudness of leaves rustling in a very gentle breeze---is also barely above the level where you hear the sounds of your own clothing rustling, the blood pulsing through your temporal arteries, and the motor drive in your CD player. As a background level for a listening room, it is overkill, but its major drawback is its impracticality. To reduce 90dB to 10dB would require about 1000' of outdoor distance from your open window to your property line. If the window is in the middle of a square plot of ground, that plot would have to be almost 92 acres in size. Try and find that in suburbia, let alone urbia!