Compression, Mastering Stage

Compression is another tool the mastering engineer uses to bring out the flavor of audio. Used effectively, compression can smooth out the piece. It raises the volume of the softer sounds and reduces the level of the louder ones, to make them all more uniform to the ear. Setting the attack and release of the compressor can yield a pleasing sense of dynamics that can set the whole mix in motion where all the instruments sound like they are on the beat and surging forward in the groove (even when they may not be). The loudest element of the mix that the attack segment "captures" will trigger the subsequent gain reduction. The decay will determine how long that reduction will last and the audio will rise again in volume till the next loud trigger comes through and starts the cycle all over gain. Mastering engineers tend to love compressors as each has a different sonic imprint on material.

Another type of compression used at the mastering phase is a multi-band compressor. This is a processor that works to both tonally balance the piece by breaking up the audio bandwidth into 3 or more bands and having a separate compressor for each.