Chorus, in the sense of backing vocals, means layering other voices over the lead vocal to add thickness and width, or the part that does so. Several people may sing the same melody, or notes may be added above and below.
The basic idea
With backing vocals, it is important to choose a register and a level that do not get in the way of the lead. Use unison on the same note, harmony on different notes, and short answering phrases as the situation calls for.
Its role in writing and performing
Adding backing vocals in the chorus increases the power and the sense of unity of the vocal. Using fewer of them in the verse and more in the chorus helps build the song.
How to check it in a DAW
Record or program the lead melody, then first layer the same melody and listen. Next add a note above or below it and check whether it sounds natural as harmony.
How it differs from related terms
In Japanese, the word chorus usually means layered vocals, while in English chorus can also mean the hook section of a song. Harmony vocals refers to adding a different pitch to the lead melody.
Layering a short backing vocal on just part of the chorus first makes the effect easy to hear.
