The paper analysis the three contextual layers of creating John Cage's Aria for solo voice performed by Cathy Berberia at the 'big stage' of musical neo-avant-garde in Darmstadt. The layers in question are: (1) the socio-political context of Germany after World War II, where the denazification process was started at the time, (2) the artistic context of neo-avant-garde musical milieu which was being formed in Darmstadt in that period, and (3) the context of a new epoch in the history of vocal art. The thesis presented here is that an encounter occurred between American experimental and European avant-garde musical practice during the accelerated denazification and liberalisation of German society and the establishment of the Cold War relationship between the East and the West. The piece Aria represents an example of a collaborative work between American and European artists, which turned to be an important step in the history of extended vocal techniques in musical performing and composing.