Power metal is more upbeat than most metal genres, taking heavy influence from heavy metal and speed metal. Power metal often emphasizes clean, melodic, high-pitched vocals, fast pacing that is mostly driven by double bass drumming and melodic lead guitar. The rhythm guitar is defined by straight power chord progressions. Sometimes, screamed vocals or gang vocals are used, but usually only as backing vocals. Power metal leans toward the positive, happy side of life, seeking to empower the listener and inspire joy and courage. Power metal lyrics usually involve fantasy or science fiction themes. Examples of power metal bands include Sonata Arctica, Helloween, Dragonforce, Iced Earth, Firewind, and Blind Guardian.