The misconception about foam being soundproof exists mostly because people lack the understanding of the differences between sound absorption and soundproofing.

It is natural to assume that if products like foam absorb sound, there will be none that is left to escape the room.

Unfortunately, sound is not like a fluid that gets absorbed and trapped in something like a sponge. The way sound behaves needs to be understood clearly here.

Sound waves are nothing but vibrations and when they strike a surface, they tend to vibrate it.

Sound does not ‘pass’ through a wall or ceiling but merely vibrates it. These vibrations are further transferred to the other side and that is how sound transfer takes place through walls, ceilings, and other surfaces.

1. Walls and Ceilings

The most common myth is that panels made of foam can be stuck on walls and will reduce the amount of sound from entering or leaving a room.

The foam that you see stuck on the walls of studios is not meant for soundproofing but is meant for sound absorption. The products that do the actual soundproofing in a studio are something else.

What You Should Be Doing Instead

You should first of all try to make your walls heavier. You can add mass to your wall by:-

Extra Drywall

Installing an additional layer or two of drywall will help to reduce sound transfer. A 5/8” thick drywall sheet weighs 2.31 pounds per square foot. That’s some serious mass and is a great substance for reducing sound transfer.

Coming back to foam, there are many varieties available and their densities vary depending on the type and grade. However, the foam would have to be several inches thick to match the mass of drywall.

Pros

• Low cost.
• Lots of mass.

Cons

• Effort and workmanship required to install.
• Involves modification of structures, so not an option for rented apartments.

Floors

• Impact Noise
• Airborne Noise

Impact noise is the noise caused as a result of footsteps or furniture being moved on the floor.

Airborne noise is the sound that is normally transmitted through the air and these include traffic noise, dog barking, neighbors yelling, and everything else.