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

 Sound 101

 The frequency of sound is expressed in wavelengths per second or cycles per  second (CPS), which is more commonly referred to as hertz (Hz). Low frequency  noise is considered 250 hertz and below, while high frequency noise is 2000 Hz  and above. Mid-frequency noise falls between 250 and 2000 Hz.  

 The amplitude of sound is expressed in decibels. This is a logarithmic  compressed scale dealing in powers of 10 where small increments in dB  correspond to large changes in acoustic energy.  

 While some noise in shared living spaces is normal, if you can clearly hear your  neighbors’ 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 noise  reduction solutions that can turn an older condo unit into a sanctuary of peace  and quiet.  

 The most problematic waves are low-end frequencies—bass signals, in other words. If you can imagine the noise transfer you hear  from a closed room,” says Keith Barkman, senior project manager at Sound Management Group in  Hillsborough. “If you're in a closed room and you hear the conversation from another room. You  probably 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, and  actually transfer into structural noise. That could be a system that creates  that—a fridge, a computer, or generators. We've run into a host of different issues  that 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 of  the biggest misconceptions is that people who live in units with concrete slabs  for walls and ceilings will be immune to any noise issues. In predominantly  wooden structures, it's the low-frequency sounds—such as heavy footfalls— that come through, whereas in a concrete structure, one gets more the  higher-end, clickety-clacking noise from heels, as well as those mechanical  vibrations that resonate especially well through concrete.  

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

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

 Combating the Clatter

 Unfortunately, many contractors and developers are not well educated when it  comes to soundproofing standards and installation. Federal housing developments  follow fairly strict guidelines for soundproofing that include expensive sound  testing for the units. But, private condo developers rarely adhere to the same  standards or test the materials that are being used to help with soundproofing.  

 “There are a couple different indicators as far as how we measure these  materials, 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 product  has. So how many decibels does a product cut down? If you have a wall  configuration that is built to have a 45 STC (Sound Transmission Class), that's  a pretty high-performing wall. They say that the uniform commercial code, the  walls are supposed to have a field-performing 40 STC, but that is usually not  the case. More often we see walls performing in the mid- to high 20s, and  that's where you start to get into issues.”  

 There's no one industry-wide accepted method of soundproofing, and that's at  least in part because none of them completely get rid of every single sound.  But, other than retrofitting your entire ceiling with new insulation and  drywall, certain materials can help dampen sound. “There's a vinyl material that's really great at blocking airborne sound, but  impact noise is a hard animal to combat. A concrete structure, you're not going  to 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 it  can be,” says Orther.  

 Wall to Wall Action

 Common wall dwellings have to meet certain codes that are set in place by either  the local building code or the national building council. A unit of measure  called Sound Transmission Class (STC) will tell you how soundproof a wall or  ceiling is. In most urban areas, a unit must have an STC of around 50 to be  within code. According to industry experts, an STC of 40 is the onset of  privacy. Once it hits 50, very loud sounds such as musical instruments can  barely be heard. At 60, most sounds are inaudible.  

 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 way  to do that is by adding shock absorbers between the ceiling or wall in an  existing structure. “Because most buildings are made of concrete, walls and ceilings will need to be  framed, lowered or extended for space,” he says. “It could take anywhere from three days to two weeks depending on the scope of  the project.”  

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

 One way to reduce noise for people below you is by carpeting the floor. The  problem is many people like hardwood floors or decorative ceramic tile, so in  these cases it's crucial to install a sound-absorbing acoustical mat before  laying down the floor. A noise issue arises when whoever is living upstairs  decides 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 require  an STC. But, the main thing they're concerned with is IIC, what's called an  impact insulation coefficient.”  

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

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

 Of all the things to get upset about when living close to others, sound issues  seem to be among the most incendiary. Lawsuits related to noise complaints are  not 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 a  serious problem. But there's things they can put under the floor. For some  reason recycled tires works great for stopping impact noises going down,” says Orther.  

 Final Thoughts

 While some of today's condo developers are taking more proactive steps to  incorporate noise control features during the construction process, even newer  buildings with concrete ceilings face many older developments where noise  between units is a big issue. “A lot of the problem is contractors do not have a clue about soundproofing. If  they did, they would save a lot of money on lawsuits. Because if a condo just  gets put up, and residents immediately have issues, they go to the contractors,” 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-end  soundproofing methods can't get rid of every single sound. Industry experts  agree that if you're going to spend tens of thousands of dollars on  retrofitting 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 that  you're not the only one in the building.   

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