Purely electronic music (dance in particular) is quite a different beast to mix compared to its electric and acoustic cousins. The lack of uneven “human factors” in the instrumental tracks makes the use of regular compression less crucial, while effects like filters, delays and… whatever’s weird, garner the front stage, together with kick and bass!
These two sounds of course share many frequencies at the bottom end of the spectrum, and also can’t really be separated with panning, because you want both of them to drive the song from the dead, deep center of the mix. Hence getting kick and bass to “live” together – without a trick – can be quite challenging.
The trick in question is called “Sidechain Compression” (also referred to as “ducking”). This process – in a few words – uses the level of the kick to control inversely the level of the bass (or anything else – lead synths for example), so that at its most extreme setting, when the kick sound reaches its peak volume, the bass will be muted, therefore letting the kick shine in all its glory while creating the famous signature “pumping” sound shared by many dance tracks.
Even though abused in electronic music, ducking can be used in any genre, also in creative ways by “chaining” two different sounds to each other.
