Voicing is the idea of which register you place a chord’s notes in, and in what order. Even for the same C chord, a low C, E, G and a higher E, G, C share the chord name but differ in brightness and density.
The basic idea
Packing too many notes into the low range muddies the sound, while spreading them upward tends to sound light and transparent. Which tone you emphasize, the root, the third, the fifth or the seventh, is also part of voicing.
Its role in writing and performing
When the accompaniment gets in the way of the vocal or the melody, changing the voicing often solves it before you start removing notes. It is the basis for separating the registers of each part in an arrangement.
How to try it in your DAW
In the piano roll, compare the same chord packed within one octave against a version spread out above and below. If there is a bass part, dropping the low root from the accompaniment makes things easier to organize.
How it differs from related terms
An inversion changes which note is lowest, while voicing covers the placement of all the chord tones more broadly. The choice of voicing also affects arpeggios.
When adding notes only makes things muddier, revisit the voicing before you change the chord.
