 Although almost entirely instrumental, the album marks Kraftwerk's first use of the vocoder, which became one of its musical signatures.According to English music journalist Simon Reynolds, Kraftwerk were influenced by what he called the "adrenalized insurgency" of Detroit artists of the late '60s MC5 and the Stooges.The input, expertise, and influence of producer and engineer Konrad "Conny" Plank was highly significant in the early years of Kraftwerk.