I know many musicians who, in the joy/stress of improvisation, sing along with the notes they're playing on their instrument. Down here, that's what is known as diddling. Back home in the Appalachians, it was usually known as chin music. In Jazz, it's sometimes called Scat Singing, isn't it? But none of the practices to which refer is performed without an accompanying instrument; so I reckon it isn't lilting.