Unwanted sound is the bane of many a New York co-op or condo dweller's existence. Few things are as annoying as being awakened in the middle of the night by a car alarm, being forced to listen to a neighbor's stereo against your will, or having to tread lightly in order to avoid disturbing the people who live below you. Noise-driven complaints can also generate serious friction between residents, leading both to festering resentment and, in some cases, to lawsuits. Fortunately, there's an entire industry dedicated to providing soundproofing solutions for almost any scenario, from the light sleeper who needs to seal noise out to the music lover who wants to seal it in. Unfortunately, the word "soundproofing" itself is a bit optimistic.

Myth vs. Reality

"We don't soundproof anything-nobody does," says Jody Cook, owner of Sound Isolation Co., a Charlotte, North Carolina firm that nonetheless sells soundproofing materials via its website (www.soundisolationcompany.com). B.J. Nash, owner of Super Soundproofing (www.soundproofing.org) in San Marcos, California, agrees. "We talk about soundproofing," says Nash, who got his start selling soundproofing materials to the aviation industry, "but we're really talking about levels of sound control that yield a level of annoyance that's tolerable."

When people like Cook and Nash refer to soundproofing, they really mean sound control or sound reduction - the art and science of reducing unwanted sound-noise, in other words-by placing something between its source (e.g., a noisy neighbor, a car alarm) and its target (i.e., your ears). Rarely can the sound be eliminated entirely.

In a multi-unit residential building, the potential sources of annoyance are nearly infinite. But according to Alan Fierstein, president of Acoustilog, an acoustical consulting firm in Manhattan, "The most common complaint for condo and co-op owners is other owners: people walking heavily, or playing the stereo too loud." Next come mechanical sources of sound such as air conditioners, elevators and exhaust fans; then nearby businesses like bars, clubs, and retail outlets that play loud music.

Under the city's noise regulations, which are monitored by a unit of the Department of Environmental Protection (DEP), construction is only allowed on weekdays between 7 a.m. and 6 p.m. Variances, though, are often issued to allow construction at other times. And devices such as air conditioning units and mechanical equipment are subject to acceptable noise level requirements. According to the DEP, it is unlawful to operate an air circulation device, (e.g., an air conditioner or fan), when such equipment raises the ambient noise level above 45 decibels, when measured inside an affected residence. Decibel levels above a reading of 85 are considered by the National Institutes of Occupational Safety and Health to be harmful to a person's hearing.

It's sometimes possible to solve noise problems through simple negotiation. Neighbors in adjoining units, for example, may be able to work out mutually acceptable "sound schedules" whereby noisy activities - music-making, apartment renovations, and the like - are limited to certain times of day. If the noise isn't so easily managed, however, it may be necessary to block or dampen it physically. Doing that, however, requires determining exactly what kind of sound it is, where it comes from, and how it travels from place to place.

"You have to understand where the sound is coming from, because sometimes it can be stopped at the source," says Fierstein. A handful of rubber-and-cork pads slipped underneath a dishwasher or an air conditioning unit, for example, can dampen irritating vibrations for just a few dollars.

The frequency of the sound involved can also be important. "The middle frequencies-like those characteristic of human speech-are the ones the ear is most sensitive to, so they don't have to be very loud [to be noticeable]," explains Fierstein. "Lower frequencies," like the ones that pour out of a stereo subwoofer, "are the most penetrating, but they have to be quite loud cause problems." A given material may block certain frequencies while allowing others to pass unhindered. And virtually anything, from glass and Sheetrock to specialized soundproofing products, can serve as a conduit for some kind of sound.

In situations where neither the source of the noise nor its remedy are immediately apparent, an acoustical consultant like Fierstein can perform a site visit, determine the nature and source of the problem using specialized equipment, and recommend a solution that can be carried out by a handy owner or a general contractor, preferably one with experience in soundproofing. Fierstein himself charges $1,000 for a typical consultation, but says his timely intervention can save far more in wasted materials and ineffective measures.

In buildings where noise problems are rampant, it may even be worth bringing in a team of consulting engineers who specialize in sound and vibration work. According to Michael A. Newman of Dunn, McNeil, Ramsay, Inc., an acoustic engineering and consulting firm based in Manhattan, most of the firm's residential work comes from managing agents who are faced with multiple shareholder complaints. Once retained, the firm will perform an in-depth investigation to determine what the problem is, and produce a written report that includes recommended solutions and estimated costs. At $200 to $300 per hour, a typical report might run between $1,700 and $2,500; but as Newman points out, the mechanical and civil engineers who perform the work "aren't handymen." And an ill-informed or ineffective attempt at solving a systemic sound problem can have serious consequences. Heavy noise and vibration from mechanical or electrical equipment, for example, can ultimately lead to the deterioration and collapse of walls and ceilings, nevermind, one's sanity.

Keeping Quiet

Nonetheless, many straightforward noise problems can be diagnosed and fixed without retaining an outside consultant. Companies like Super Soundproofing and Sound Isolation provide basic information about soundproofing on their websites, and will counsel clients over the phone regarding common complaints. "This is pretty much cut-and-dried stuff," says Nash. "There are simple answers for most of it."

"The first thing we tell people is to put standard insulation in the floor, ceiling, or wall," says Cook, thereby reducing its ability to propagate sound. For his part, Newman recommends using acoustical insulation, which is far more effective than blown insulation. To soundproof further against airborne noise like speech or music, a layer of mass-loaded vinyl (MLV) can also help. MLV sells for approximately $1.50 per square foot, and is sufficiently dense to reduce sound transmission significantly. But it also illustrates the need to understand exactly what the problem is, and to choose the right tool for the job. For example, Cook cautions that slapping MLV over an existing surface may not block all low-frequency airborne noise. And according to Nash, putting a layer of MLV down over your floor will do nothing to appease the downstairs neighbors who complain of heavy footsteps, since the material doesn't block impact noise at all.

One of the most effective ways of reducing both airborne and impact sound is to isolate or "float" the offending ceiling or wall. Floating a ceiling involves attaching a second layer of drywall to the existing one using special sound isolation clips that screw into what's called a "furring channel." The second surface is thereby acoustically isolated from the first, and the space between the two can be filled with acoustical insulation. A layer of MLV can even be added for good measure. The end result, says Cook, is a wall or ceiling whose sandwich-like structure creates "a torturous path for noise." Total material costs for such a system run approximately $2.50 per square foot.

Before spending that kind of money, however - and shaving a few inches off your existing ceiling - you might want to investigate other, simpler remedies. Fierstein can recall at least one case in which neighbors were able to solve their upstairs-downstairs noise problems by caulking the seams of their walls, floors and ceilings for less than $100.

Outside Influences

If external noise is the problem, upgrading your windows might be the solution. Windows in historic or landmark buildings in particular can be "extremely poor in terms of their acoustical value," says David Skudin of CitiQuiet, a window company based in Long Island City. Skudin's voicemail often catches "frantic 2 a.m. calls from people who paid $1 million for their co-op and can't live there. A lot of clients don't anticipate the full impact of the environment around them," he says.

CitiQuiet produces custom-made interior soundproofing windows that can block anywhere from 50 to 95 percent of incoming noise. The degree of noise reduction depends on the thickness of the glass, the quality of the window seal, and the amount of dead airspace between the new window and the original one. And since price is tied to soundproofing ability, the amount you pay depends on how much quiet you need: A six-foot tall, three-foot-wide double-hung window that reduces noise by 50 percent might run $800, while a window of equal size that reduces sound by 90 percent might run $1,100. As with most soundproofing solutions, it all boils down to a balance between cost and efficacy. "A client may accept 70 percent noise reduction in the living room, but want 90 percent in the bedroom," says Skudin.

Skudin's colleagues agree that windows are one area in which a do-it-yourself attitude may be misplaced. "A real acoustical window is heavily engineered," says Nash, and "must be tested in an acoustical lab." Installing your own double- or triple-glazed window won't necessarily get the job done, in part because it may block certain frequencies while allowing others to pass right on through.

Quiet From the Ground Up

The professionals also agree that it's usually cheaper to incorporate soundproofing concepts into a building during the design and construction stages, as opposed to tackling an existing problem later on.

"A lot of people don't realize that when they build something, they can build it using sound control techniques without spending much," says Nash. Using acoustical insulation in walls and ceilings-or even applying an additional half-inch of drywall-can significantly reduce sound transmission, as can staggering the placement of electrical outlets, wall switches and medicine cabinets, which might otherwise channel sound from unit to unit. And when installing floors, it's best to avoid tile and marble, both of which are "tremendous broadcasters of sound," says Newman. Concrete can cause trouble as well: Fierstein saw one client spend $300,000 to replace a concrete floor following a commercial-to-residential conversion. "Concrete can transmit sound surprisingly well," he notes dryly.

Newman does see some architects taking sound issues into consideration when designing structures, "Especially in larger units, where people are spending a fortune and don't want to be disturbed." But it's hardly the kind of thing you can count on.

All of which can make some expert advice all the more useful, especially when it comes to something as potentially disruptive as noise, and as potentially expensive as soundproofing.

"There's no limit to how much money you can spend," says Fierstein. "But you have to find the right compromise."

Noise complaints can be reported to the city's 311 Citizen Service Center hotline. Over its first two years of operation and a whopping 18 million calls-620,185 calls-were noise-related.

For a sidebar story on noise levels in the Big Apple, click here.