 Following a largely organic and uncalculated impulse , many of these new bands infused classic heavy metal with the immediacy of pub rock and the intensity of punk rock , implementing to various degrees the crossover of genres started by Motörhead ; in general they shunned ballads , de @-@ emphasised harmonies and produced shorter songs with fast tempos and a very aggressive sound based on riffs and power chords , featuring vocals ranging from high pitched wails to gruff and low growls . Iron Maiden , Angel Witch , Saxon , Holocaust , Tygers of Pan Tang , Girlschool , Tank and More are notable performers of this style , which bands such as Atomkraft , Jaguar , Raven and Venom stretched to produce even more extreme results . Critics consider this new approach to heavy metal the greatest musical accomplishment of the NWOBHM and an important evolutionary step for the genre . 
