Our homes buffer us from the noisy outside world. If you live out in the country, noise may be less of a problem (unless you live next door to a farm). Birdsong is a pleasant sound. But if you live next door to a fledgling drummer, or an airport, or if you are a concert pianist, then residential noise control is important to you.

Sound is blocked by solid, massive and airtight barriers. The thicker the barrier relative to the wavelength of sound, the better it will block sound. Low frequency sounds have longer wavelengths; to a low frequency sound, even a thick wall may be relatively thin. You can hear this if you have been in a room with a television next door. You can't make out individual voices because the wall blocks the high frequency sounds necessary for understanding speech. The lower sounds get through, however, making an irritating mumbling sound.

There are several modern trends that exacerbate the problem of residential noise control. First, we have the unfortunate phenomenon of amplified music. Perhaps the most difficult noise-problem of all is the electric bass. The mindless throbbing of this instrument is nearly impossible to block, as anyone who has lived next door to a teenager (of any age) can attest.

Modern buildings generally have lighter construction, exacerbating this problem of low-frequency sound penetration. Lighter construction also allows vibration to travel more easily. On the other hand, the modern house tends to be airtight. In addition to the heat-efficiency benefits, this tends to improve sound isolation-except for vibration and low frequency sound.

The first step in noise-proofing a house is to improve the doors and windows, since these are the weak links. Even a gypsum-board wall is a better noise barrier than most windows. For more effective noise isolation, one needs to build additional layers. For example, to isolate vertically-stacked apartments, one can hang an additional ceiling. The trick is to hang the new ceiling in such a way that there is no rigid contact between layers. We took this approach for the Danzante Dance studio in Harrisburg PA, located directly below an apartment. Flamenco tableaux in the studio do not bother the residences in the apartment above.

In the freestanding suburban house, noise control is less often a serious issue. This is one reason people move to the suburbs. However, residential noise control will increase in importance as baby boomers move back to the big cities to reimmerse themselves in the cultural life of cities after their children have grown.