A death growl (or simply a growl) is a vocal style (an extended vocal technique) usually employed by death metal singers but also used in other heavy metal styles, such as metalcore. Death growls are sometimes criticized for their “ugliness”. However, the harshness of death growls is in keeping with death metal’s abrasive music style and often dark and obscene subject matter. The progressively more forceful enunciation of metal vocals has been noted from heavy metal to thrash metal to death metal.

Was reading this during an Eluveitie concert. I did not know unclean vocals have a scientific definition.