Range is the span of pitches a voice or an instrument can produce, or the span used within a song. What matters is not only how wide it is from low to high, but also which part of it sounds effortless and beautiful.
The basic idea
Moving the same melody up an octave changes how singable it is and how the instrument sounds. Too low or too high, and the stability of the performance and its expressiveness can suffer.
Its role in writing and performing
Deciding the key for a vocal, separating the bass from the accompaniment, bringing the lead forward – arrangement requires designing the ranges.
How to check it in a DAW
Look at the keyboard in the piano roll and check which span each part uses. Change the octave and compare how singable it is and how it overlaps with the other parts.
How it differs from related terms
Range is the span of pitches available, and pitch is the height of a single note. Timbre differs by instrument even in the same range.
Rather than adding more high notes, choosing the spot where each part sounds comfortable makes a song easier to listen to.
