Sonic space is the frequency range that an instrument or a vocal sound takes up when it is played. That’s the short definition but it’s like saying paint is red or green in color without talking at all about what happens when you paint one color over another when the paints are still wet.
If we had a bass player, a tenor singer, and a piccolo on the stage and we had to mix these instruments, we could do it without worry of the sonic space each instrument takes. I’m not saying those three together would sound good but as far as frequencies in use, they are not going to overlap.
Kick that grunge band off the stage and bring up two guitarists and a pianist. Gulp. Now there are three instruments in the mix that take up the same fundamental frequencies. When it comes to mixing these instruments, you’re going to have a tough time separating those sounds so they give the appearance as three distinct instruments. The problem is they are sharing the same sonic space, especially if they are all playing around the same octaves.
When too many sounds occupy a given frequency range, then the entire mix can sound fuzzy and certain elements can begin to disappear. Therefore, sonic space must be respected by both the sound operator and the band.
First, musicians must realize that when multiple instruments that have common fundamental frequencies play in / across the same octaves those sounds are occupying the same sonic space. The more instruments that do this, the fuzzier the overall sound and less distinct each individual instrument. By moving to different octaves, they can identify each other in that sonic space even if they do still share some frequencies. This isn’t to say they can’t share a sonic space, after all, there is a lot that can be done with music and layering and the sound operator.
Second, you (the sound operator) must recognize what you can do to highlight instruments that share a common sonic space. For example, if you have two acoustic guitars, EQ each one differently so that each one is highlighting different frequencies. Perhaps you give one a bassy warm feeling and you give the other a brighter sound. This requires a lot of ear work because you still want to EQ the guitar so you bring out its best tone. If you are running in stereo, you can pan the instruments a little left and right. This enables you to give the music a three-dimensional effect.
Understanding sonic space will help you put paintbrush to that next audio painting. Your tools for painting are EQ, panning, effects, and musical instruments. Now let’s add in some happy trees.