Q. I am currently working on my basement as a home theater. I would like to soundproof the space without spending thousand of dollars. Can you give me any ideas of how to do this as frugal as possible while still creating a good sounding room? - Deon

These are two entirely different questions that will take two different answers. Your second sentence implies that you want to acoustically isolate your theater so that noise does not filter in and sound does not bleed out to the rest of the house. Your third sentence implies that you want to acoustically tune your room for best sound. While it is important to acoustically isolate the noise from your theater room for better sound, these two concepts are very different. Let’s discuss Isolation.

There are really two aspects to sound isolation. One is keeping sound in and the other is keeping sound out. Let’s consider the level and the source of noise that might get into your theater. Do you live in a dense urban environment? Is there a hard surface floor above the room where people walking will be heard? Sit in the room quietly, do you hear your HVAC system? Let’s discuss 5 principles of sound isolation and cost effective ways to make these work.

Decoupling
This cost effective solution inhibits the movement of sound from one side of the wall to the other through mechanical paths such as studs. The vibration must then pass through an air cavity and absorbing material in the wall. The use of sound isolation clips and hat channels or resilient channels are readily available and relatively inexpensive. Ordinary drywall is screwed to the channel that is “floated” by the isolation clips. This will provide an increase of your sound transmission class from 34 to 57.

Mass
It is harder for sound to move through heavier items than light items. However, to make a large difference you need a lot of mass. Adding mass to all surfaces after sound isolation will easily block most of mid and high frequencies. Again this low cost solution is available by adding just one more layer of drywall.

Absorption
Insulation in the wall or ceiling cavities will increase your isolation by removing some of the sound. This is ineffective at lower frequencies. However, very beneficial with mid and upper frequencies when used with the decoupling technique. Standard common fiberglass used in construction is effective.

Resonance
Resonances in a room will hurt you with the above three items and vibrate walls, ceilings and even floors. If a train passes, even decoupled walls with insulation will vibrate causing air on the other side to transmit. The easiest solution is to use visco-elastic damping compounds or predamped drywall and flooring.

Conduction
Noise that travels from one room to another by an indirect method must be eliminated. To eliminate vibrations or sound that can become structure born you must treat the surfaces on the source side. Some easy solutions are to not flank your electrical outlets back to back in the wall.  As well, reduce the amount. Have a sacrificial false ceiling so light fixtures do not allow sound to transmit.

There are other ideas, but these are the most inexpensive. By creating a quiet environment inside the room, you will ultimately enjoy the real sound that your system produces.

About the Author:
John Baumeister - President, Baumeister Electronic Architects

As a renowned industry expert, John Baumeister has been educating Chicago's leading architects and designers on lifestyle technologies for years. His mantra of providing world-class service for world-class clients has empowered Baumeister to become the area's most trusted system integrator.