Timbre is the quality of sound that lets you tell instruments and voices apart even at the same pitch and the same volume. A piano and a guitar sound different, and so do two presets on the same synth, because their timbre differs.
The basic idea
Timbre changes with the combination of harmonics, attack, decay, and noise. Impressions such as bright or dark, hard or soft, and near or far also relate to the choice of timbre.
Its role in writing and performing
Timbre has a huge influence on the genre and the world of a song. Choosing sounds that fit their roles, making the lead stand out or pushing the accompaniment back, is part of arranging.
How to check it in a DAW
Play the same MIDI phrase through several instruments and compare them at matched levels. Move the filter, the envelope, and the effects one at a time and listen to what changed.
How it differs from related terms
Timbre is the character of a sound, pitch is its height, and volume is its size. Separating the three makes synth and mix controls easier to understand.
The timbre that fits a song is not necessarily the one that sounds flashy on its own. Choose it while layering it with the other parts.
