Better Neighbors Through Soundproofing - Can You Hear Me Now? (2024)

When walls are the only separation between you and your neighbors, privacysometimes goes out the window. People hear their next-door neighbors talking,footsteps from above or even music blaring through the walls. Soundtransmission between units is one of the biggest complaints among condodwellers. Noise can also come from ceilings, doors and windows, so living in amultifamily building could take some getting used to.

The amplitude of sound is expressed in decibels. This is a logarithmiccompressed scale dealing in powers of 10 where small increments in dBcorrespond to large changes in acoustic energy.

While some noise in shared living spaces is normal, if you can clearly hear yourneighbors’ conversations or TV through your walls or ceiling, you have a noise problem. If you’re willing to make the financial investment, there are innovative noisereduction solutions that can turn an older condo unit into a sanctuary of peaceand quiet.

The most problematic waves are low-end frequencies—bass signals, in other words. If you can imagine the noise transfer you hearfrom a closed room,” says Keith Barkman, senior project manager at Sound Management Group inHillsborough. “If you're in a closed room and you hear the conversation from another room. Youprobably won't hear the mid-range frequencies; you'll hear the lower range,bass frequencies of the voices.”

“A lot of times, low-end frequency will be transmitted through the wall, andactually transfer into structural noise. That could be a system that createsthat—a fridge, a computer, or generators. We've run into a host of different issuesthat are both airborne and structure-borne,” says Barkman.

Many buildings now use concrete structures that support more units and floors.Concrete may be more durable, but sound-wise, it can pose a challenge. One ofthe biggest misconceptions is that people who live in units with concrete slabsfor walls and ceilings will be immune to any noise issues. In predominantlywooden structures, it's the low-frequency sounds—such as heavy footfalls— that come through, whereas in a concrete structure, one gets more thehigher-end, clickety-clacking noise from heels, as well as those mechanicalvibrations that resonate especially well through concrete.

When a sound wave hits one side of a wall it transforms into a vibration, whichwill travel from the sheetrock, to the stud and into the sheetrock on the otherside of the wall. Because it does not have any other hard surfaces to travelthrough, it becomes an airborne sound again.

“You can measure it with a sound meter,” says Bob Orther, president and senior technical advisor for SoundproofingAmerica, a national company. “The way they come up with the [Impact Insulation Class] IIC rating is with ahammer test. They go upstairs and hammer the floor, and look at the decibelsdown below.”

“There are a couple different indicators as far as how we measure thesematerials, and what we can expect from the materials in the field,” says Barkman. “Basically, we look at the amount of sound attenuation that a certain producthas. So how many decibels does a product cut down? If you have a wallconfiguration that is built to have a 45 STC (Sound Transmission Class), that'sa pretty high-performing wall. They say that the uniform commercial code, thewalls are supposed to have a field-performing 40 STC, but that is usually notthe case. More often we see walls performing in the mid- to high 20s, andthat's where you start to get into issues.”

There's no one industry-wide accepted method of soundproofing, and that's atleast in part because none of them completely get rid of every single sound.But, other than retrofitting your entire ceiling with new insulation anddrywall, certain materials can help dampen sound. “There's a vinyl material that's really great at blocking airborne sound, butimpact noise is a hard animal to combat. A concrete structure, you're not goingto have a problem with airborne noises like you would with a wood structure.Wood in general is not really a good sound-proofer, but if it's dense enough itcan be,” says Orther.

Gene Ferrara, owner of JMA Consultants & Engineers P.C., in Englewood Cliffs, says that for soundproofing a residence,it’s important to minimize vibration from one surface to another and the best wayto do that is by adding shock absorbers between the ceiling or wall in anexisting structure. “Because most buildings are made of concrete, walls and ceilings will need to beframed, lowered or extended for space,” he says. “It could take anywhere from three days to two weeks depending on the scope ofthe project.”

One option is to install acoustical insulation, although that means taking wallsdown to the studs. Another alternative is using dB-Bloc, a vinyl sound barriermaterial, which can be layered behind drywall or other finished wall or ceilingsurfaces to help block noise transmission through common walls. Diffusers and reflectors can also be used toreshape reflective energy where walls and ceilings create acoustical mirrors.Diffusers and reflectors keep volume the same as untreated walls and ceilingswhile changing the shape of the noise.

One way to reduce noise for people below you is by carpeting the floor. Theproblem is many people like hardwood floors or decorative ceramic tile, so inthese cases it's crucial to install a sound-absorbing acoustical mat beforelaying down the floor. A noise issue arises when whoever is living upstairsdecides they don’t like carpeting, installs wood floors and doesn’t put in a soundproofing mat or agent underneath, says Orther. “And they're usually doing it illegally, because most condo associations requirean STC. But, the main thing they're concerned with is IIC, what's called animpact insulation coefficient.”

It’s not just the walls and ceilings you have to worry about when it comes tonoise. Noise can sneak in through any gaps in openings, including doors,windows, outlets, switch boxes, HVAC openings, and anywhere building materialsmeet. “I always tell people, do not put recessed lights in your ceiling, because that'sjust a big hole in your ceiling. That said, if you have a concrete ceiling, itmight not be a problem because you're talking about the impact noise. It willcome through the lights,” says Orther.

Sealers can be very cost-effective sound-killers, yet they are often the mostoverlooked step in noise control solutions. These can include door seals,automatic door bottoms, thresholds, and acoustical caulk. Also good forsoundproofing are noise barriers, which are always high density, massive, heavymaterials and are essential for eliminating noise transmission.

Of all the things to get upset about when living close to others, sound issuesseem to be among the most incendiary. Lawsuits related to noise complaints arenot uncommon, and some associations are taking matters seriously. “If there is a provision in the bylaws, and they don't meet that, then there's aserious problem. But there's things they can put under the floor. For somereason recycled tires works great for stopping impact noises going down,” says Orther.

It almost goes without saying that some unit owners can obsess over sounds,especially when trying to sleep or relax. But, even the highest-endsoundproofing methods can't get rid of every single sound. Industry expertsagree that if you're going to spend tens of thousands of dollars onretrofitting your home for sound, don't expect a cure-all. Living above, below,and next to fellow owners, you will likely from time to time be reminded thatyou're not the only one in the building.

Keith Loria is a freelance writer and a frequent contributor to The New JerseyCooperator. Editorial Assistant Tom Lisi contributed to this article.