What is a person called who sings alone?

Answer 1

A soloist.

Answer 2

It is called an Aria.

That depends. If the song is part of an Opera, it is an aria. If it is not part of an opera, it is called an art song. Art songs in different languages have different name; for example, if you're singing in German, you are singing a lied.

Answer 3

Accapella is when voices sing without instrumental accompaniment.

Answer 4

A song sung alone by one person is called a solo

Answer 5

With music, a solo. With no music, acapella.

Answer 6

Background or accompanying music. Or an instrumental work.

Answer 7

Soloist