Tips on Soundproofing

Every sound engineer knows what a headache it can be to try and get rid of that annoying buzz or hum, which makes to best of us want to burn our speakers to ashes. One of the most common culprits for this problem is poor soundproofing.

As a whole, soundproofing is quite an involved science, but at its core it boils down to a few basic concepts: Room shapes and sizes, isolation, what materials to consider and acoustic treatments.

As far as the shape of any recording space is concerned, the biggest problem to consider is parallel walls. When two walls are exactly opposite each other, sound bounces directly between the two parallel surfaces, which causes a phenomenon known as standing waves. The result is a resonance in the room at specific frequencies. This is the reason why we notice low frequency bass sounds to be louder along the walls and corners of rectangular rooms.

The best solution for evening out the sound in your room is to place bass-traps in the corners of the room to effectively absorb the excess low frequency resonance in the room.

The next thing to look at is the size of the room and how it relates to the room’s reverberation time. The bigger the room, the bigger its reverberation time. Typically the room in which you plan to mix music should be more on the dead side, i.e. have very little reverberation. In essence the main idea is to use acoustic panels made from either Rockwool or acoustic foam, to absorb sound in the room until the reverb is reduced to the point where the sound of the room you’re in no longer affects the sound coming from your speakers. This allows you to make better mixing decisions, because you’re not compensating for the sound of the room.

Isolation is probably the biggest part of acoustic treatment. The reason is simple: It’s better to avoid noise rather than to try and get rid of it in your mix. The most common techniques is to build specially treated walls that are decoupled from the main walls and floor, which effectively stops sound vibrations from traveling along the outside walls and along the floor and into your microphone. Other techniques include thicker, acoustic-grade glass windows, heavier and thicker doors and to acoustically isolate the HVAC (Heating, Ventilation and Air Conditioning) system to make as little noise as possible.

It’s worth noting that soundproofing is one of the most expensive parts of creating a recording space, but is well worth the costs and trouble and goes a long way to aid in achieving a professional, quality sound that we as sound engineers strive for.