 Since the mid @-@ 1950s , Stockhausen had been developing concepts of spatialization in his works , not only in electronic music , such as the 5 @-@ channel Gesang der Jünglinge ( 1955 – 56 ) and Telemusik ( 1966 ) , and 4 @-@ channel Kontakte ( 1958 – 60 ) and Hymnen ( 1966 – 67 ) . Instrumental / vocal works like Gruppen for three orchestras ( 1955 – 57 ) and Carré for four orchestras and four choirs ( 1959 – 60 ) also exhibit this trait ( Stockhausen Texte 2 : 71 – 72 , 49 – 50 , 102 – 103 ; Stockhausen 1989 , 105 – 108 ; Cott 1973 , 200 – 201 ) . In lectures such as " Music in Space " from 1958 ( Stockhausen Texte , 1 : 152 – 75 ) , he called for new kinds of concert halls to be built , " suited to the requirements of spatial music " . His idea was 
