Soundproofing A Room 101

Whether you are soundproofing a home studio or rehearsal space, or you just want to have a little bit of peace and privacy in a noisy multi-resident building, the basics of soundproofing a room remain the same.  Sound is a form of energy that can be very difficult to manage without knowing exactly what your goals are in soundproofing a room.  Are you trying to keep sound from your noisy neighbor out, or are you trying to keep the sound from your home theater or recording studio in?  Both require similar soundproofing techniques but having access to the source of the sound (home theater, recording studio) will make soundproofing a room easier to manage than trying block the sound on the receiving end.

Soundproofing a room effectively requires you determining which of the two types of noise you are experiencing, airborne or impact noise.  Airborne noises such as a crying baby, a dog barking, or a television’s surround sound speaker system are all examples of noise that uses air a medium for travel.  This type of noise is much easier to block when soundproofing a room compared to impact noise.  Impact sounds occur when one object collides with another creating a vibration that uses the wood, screws, and drywall in your walls as a medium for travel.  This type of noise is much more difficult to manage because it can travel in all directions and enter your room through multiple locations (Flanking Noise).  For example if your neighbor above you in your apartment has heavy footsteps, the sound is likely entering your room from the ceiling and walls.  However, it is still possible to make improvements soundproofing a room in your home and finally get the quiet you deserve.

Sound Transmission Class (STC) – STC is a term you will encounter frequently when soundproofing a room.  It is the metric by which soundproofing materials are rated against one another, more specifically how well a building partition attenuates (reduces) sound.  The higher the STC rating of a product or soundproofing technique, the better it blocks unwanted sounds.  As a reference, the human ear perceives an increase in STC by 10 as a 50% reduction in sound.  As an example, if a standard interior wall has an STC rating of 40, and you increase that rating to 50 by soundproofing a rooom, you will perceive it as a 50% reduction in sound.  As a guideline, normal voices are inaudible at a rating over 40, while a musical instrument will seem faint or inaudible at an STC of 50 or higher.

Materials For Soundproofing A Room

There are a variety of techniques for soundproofing a room with very different costs and effectiveness.  However, the underlying goal of almost every method of soundproofing a room is to break the path by which sound travels.  In traditional construction, every room is somehow connected to one another.  Sound can travel from the drywall, through the screws that go into the studs and throughout the rest of the house.  Soundproofing a room is as simple as creating a sound blocking gap between your walls and the source of the noise.  There are a number of soundproofing materials on the market that achieve this goal effectively.  Combining multiple techniques yields the best results when soundproofing a room.

Resilient Channel – If you are in the planning or construction phase of your home, or if you are remodeling, resilient channel is a great method of separating your drywall from the studs that make the wall.  It creates the framework for applying your drywall with the least amount of structural material possible.  However, not properly installed, resilient channel can be utterly ineffective.  Read our article on resilient channel for more information.

Soundproof Drywall – Soundproof drywall such as QuietRock 545 boasts an STC 60 rating.  QuietRock is an 11 layer ceramic composite gypsum board that replaces the need for other materials like resilient channel used for soundproofing a room.  However it has an estimated cost that it is over 10 times that of traditional drywall making it too expensive for many customers.

Sound Damping Glue – One of the most cost effective methods of soundproofing a room.  Sound damping glue such as Green Glue, when sandwiched between two layers of drywall can increase your partition attenuation to a rating of up to 55 STC.  The added benefit of a product like Green Glue is that is does not require tearing out the existing drywall.  Simply add a layer of the sound damping glue and a sheet of drywall to significantly improve your home’s privacy.

Soundproof Insulation – When soundproofing a room, insulation can be used to “break up” the sound in the air gaps between walls.  In general you want to use an insulation that is less dense and has more air pocket or “cells” such as cellulose.

Soundproofing A Room The Right Way

The easiest way to soundproof a room is to plan on using the proper materials and techniques before beginning construction.  That usually means using products like resilient channel and QuietRock soundproof drywall in the room that is the source of the noise.  For example, you would employ all of the best soundproofing a room techniques in your home theater, rather than try to sound proof the six rooms that may be effected by the noise.  This is the most effective and inexpensive way of soundproofing a room, also decreasing the possibility of flanking noise.  It is also possible to use products like sound isolating joist hangers, and sound barriers to help soundproof your floors and ceiling.  Unfortunately, most people don’t have this type of luxury.

How To Soundproof A Room The Easy Way

Unfortunately most people want to know how to soundproof a room after they’ve already built or moved into their new home.  This type of post construction soundproofing a room can be a little bit more costly, but thanks to the recent improvements in acoustical technology, products like Green Glue make it easy.  As always the easiest way to soundproof a room is to soundproof the source of the noise itself.  If you are building a home studio, or rehearsal space, then using either resilient channel, or Green Glue will in conjunction with a proper soundproof insulation should give you the freedom to play as loud as you’d like most hours of the day.

If you are trying to block out the noise of noisy neighbors, but you live in an apartment where deconstructing the walls is not an option, there are a few alternatives to putting up another layer of drywall.

• Fill All Gaps – Make sure your room is airtight as a first step in soundproofing a room.  In the same way that outdoor noise is much louder even if a window is just slightly cracked, even small leaks in your walls can transmit sounds much louder than a properly sealed room.  Common places for leaks include the space around electrical outlet boxes, window frames and moulding, and door casing.  Get a can of insulating foam like Great Stuff and fill all of the voids around your electrical boxes.  Also get a few tubes of clear or white silicon and re-chalk all of your window and door frames, and trim moulding.
• Thick Curtains – You can greatly improve the effectiveness of soundproofing a room by fixing the weak zones like windows and doors.  Once you’ve made sure there are no air leaks, hand a set of thick or soundproof curtains to help eliminate some of the noise entering though the panes of your window.
• Soundproof Blankets – If you are not concerned with the aesthetics of your method soundproofing a room, soundproof curtains can be hung on your walls temporarily to help block sound and increase your STC rating.  Acoustic blankets can reduce the level of noise in your room up to 21dB.

Whatever your reason for soundproofing a room, there are a number of options available, some that are extremely effective, some that offer great value for the money.  Remember to consult a licensed contractor before soundproofing a room.