I know when people sing in clean voices, they practice singing in right pitches or in key. They practice getting there voices the same notes as the guitar by playing a note in a guitar or keyboard or piano and than trying to sing that same note. They make their voices the same note as the instrument. Or when chords are played, for example a Dm chord with notes (D F A) the singer tries to sing one of those note like F for instance. But it would sound crappy if his voice was flatter or sharper than F and even worse if it is a totally different note that isn't D F or A. That is why it is important to sing in key or pitch of the song. My question is does the same rule apply when people sing in black, death metal screatch and growls, like Norther, Children of Bodom, Dimmu Borgir, Cradle of Filth etc? Does anyone know of any tuners for voice so you can see the notes you sing?

when you sing (read: sing, and NOT just mumbling or uttering words), it kinda comes naturally that your voice tries to atune itself to the key, whether you're growling or singing clean.

__________________

Growling generally has only one note.