You may have heard it said that there are three dimensions in music: width, height, and depth. By taking advantage of all three dimensions you can create clarity and space in your mix. Width is represented by the stereo spectrum, panning things left, right and in between. Height can be represented by volume; quiet parts seem buried while louder parts sore to the top of a mix.
And then there is the third dimension, depth, usually represented by how dry or wet a signal is. More reverb or delay “places” the signal far back from the listener, while a dry sound keeps the track in your face. But did you know that reverbs and delays are not the only way to create depth in your mix? That’s right, you can easily affect a signal’s depth by using EQ!
Via Jared Tarbell Flickr
Mixing Is Just An Illusion
Since mixing music is truly all smoke and mirrors, an illusion, our job as audio engineers is to use the tools at our disposal to trick the listener into hearing something intentional. We want the final result to sound like a real band playing in real space, with every musician being heard equally. This is hard to do because there are no visual cues like at a live concert.
At a show, I can quickly see the band and have a visual indicator of when (or if) they are playing and how intense they are performing. That helps tell my brain what to focus on in the live mix. With a recording, however, we need to create space and depth so that the listener perceives the same thing. We typically reach for things like reverb to place a sound a bit further back in the mix, which in turn keeps something else (lead vocal, guitar solo, etc) right up front as the focus.
Look Mom, No Reverb!
But think about this for a moment. Sound that is close to us in physical space usually sounds bright and clear. Whereas sound that is coming from farther away tends to sound a tad bit duller. In other words, we perceive sound from far away as having less high frequency information than sounds that are close to us. We can still hear things from farther away, we just lose some of the clarity. Knowing this phenomenon means we can take advantage of it in our mixes.
If we want to place an instrument or track farther back in our mix, than instead of reaching for a reverb, we could simply place a low pass filter (LPF) via an EQ plugin on the track and roll off some of the high frequencies. An LPF is the exact opposite of a high pass filter, in that it let’s the lows pass, but cuts the highs. The more high end you roll off, the less present and “up front” that instrument will sound. Consequently the unaffected tracks (the ones with no LPF) will sound closer and more “up front”. See how this works?
Every Track Can’t Hog The Spotlight
At the end of the day, we can’t assume that a mix will sound balanced and clear if every track is pushing to be up front in the mix. Our ears will be bombarded with sound and won’t know where to focus. Good mixes are the ones where each track has its place, and one way to help this is with depth, either through the use of reverb or EQ. So go ahead, be confident, and commit to your most important sounds in a mix by pointing out the less important (i.e. supporting role) sounds and placing them farther back in the mix.