Influenced by the heavier-sounding blues-based rock bands such as Cream, Led Zeppelin, Deep Purple and Iron Butterfly, Black Sabbath put a ‘doomier’ spin on this sound to reflect the working class conditions of industrial Birmingham. This resulted in their eponymous debut album that is widely regarded as the starting point of metal music from which many subgenres spawned. In Britain, this developed into the New Wave of British Heavy Metal (NWOBHM) which was a retaliation to 70’s popular music such as Elton John and the Bee Gees. It infused the influence of heavy metal with the energy of punk and incorporated a greater emphasis on musicianship and technicality.