revving a note

When a musical note from a singer sounds like revving a car. It's mostly used in songs that lacks emotion. So the singer overcompensates by revving the note to get more emotion out of it.

Like in the song Soon by Leann Rimes, at the beginning where she sings "SooOOoooOOon" (Revving a note).
Like revving a car "RuUUuuUum RuuuUUuum"