http://www.invisibleoranges.com/2010/07/ask-a-real-musician-5-classic-male-metal-singers/

Excerpt concerning Bruce Dickinson of Iron Maiden:

“I have nothing but admiration for this singer. Listen how he starts off with a soft growl, then moves seamlessly into a well-supported, sustained high full-voice sound that then evolves into an effortless long scream! His diction is easily intelligible, regardless of the range he’s singing in or the effect he’s going for. He achieves an intensely rhythmic delivery of the lyrics without losing legato and musical momentum, something a lot of classical singers struggle with, especially when interpreting the many staccato and accent markings that crowd scores by Bellini, Donizetti, etc.”