Acoustic Treatment – Whats the big deal?
May 13, 2011
Why do I have to acoustically treat my mixing room?
The music you are listen to was most likely mixed in an acoustically treated room. Rooms designed for mixing sound extremely balanced through the whole audible spectrum, 20hz – 20khz. In an untreated room, reflections from walls and solid surfaces will overlap other existing sound waves. This results in positive and negative interference. Positive interference results in an increase in amplitude relative to the source amplitude. A negative interference means the sound wave in question has less than the initial source amplitude, or even an amplitude or zero. If you try and mix in an untreated room you will overcompensate and under compensate equalization and volume levels at particular frequencies due to this interference phenomenon. When your mix sounds great (balanced) in your untreated room you will bounce the file and burn your CD. You go out to your car or living room stereo and take a listen. Now your hearing what you really have saved to CD, an unbalanced mix, the bass may be too loud or too quiet, the high end may be piercing or missing all together.
So, by treating your room acoustically, you give yourself a better starting point for creating a balanced sounding mix. Cover drywall in a combination of 2” foam and wood paneling. Place broadband absorbers in corners and above your mixing position. Put a rug or two down on hardwood flooring. Parallel walls are your enemy, this includes floor and ceiling. Some 4” acoustic foam placed here and there on the ceiling, along with rugs on the floor, will help to diminish reflections between the floor and the ceiling, thus lowering the amount of overlapping waves (positive and negative interference).
The same interference problems exist when tracking. Things get more complicated when using two or more microphones simultaneously (phasing – interference tracked to tape). So its just as important to have a well balanced tracking room/isolation booth. In general, tracking in a balanced room will give you more control over your source sounds and give you higher quality tracks to work with. Mixing in an acoustically treated room allow you to balance all these great tracks into a professional sounding 2-mix.