Fred Frith: "In 1957, Lukas Foss founded the Improvisation Chamber Ensemble, a quartet devoted to what he described as 'un-notated music'" (208)
disbanded 1962
Pauline Oliveros is doing improvisation around the same time with Terry Riley and Loren Rush:
"Terry, Loren, and I had been doing these improvisations, and we were kind of excited about it. And when Lukas Foss came to town, he was supposed to come and do improvisation. We were very excited to hear another group doing improvisation, So we went to the concert. But we were all kind of looking at each other and wondering, because they all had music stands. [Laughs.] They were doing 'guided' improvisation, And afterwards we asked the question, 'What would happen if you didn't use music stands?' And Lukas Foss said 'It would be utter chaos.' So what we understood was improvisation was not what he understood was improvisation." (98)
see their 1958 KPFA tapes
Frith notes that these tapes are "experimental music in the purest sense of the word [...] [It] doesn't seem to be situating itself self-consciously in relationship to jazz* or anything else" (209)
*Frith has previously (208) noted that composers of this era were fundamentally trying to figure out "how to distance [improvisational] practice from jazz," and he notes that George Lewis has "addressed the subtle and not so subtle racist attitudes" that may have emerged from practitioners who took this as a primary objective