You should remember that technically it wasn’t very difficult to do this stuff with tape recorders. Pulling a tape through any reel to reel while the transport was stopped would let you manually move the tape or reels any way you wanted. “rocking the reels” this was way how you found splice points. Of course Laurie Anderson made it theatrical by putting the tape on a violin bow and the playback head on a violin body - totally cool idea, but same basic thing Frederik was doing with his tape of his dog.
Splicing tape was something that “everyone” did. Eno, Czukay, and TG were famous for using it creatively, but any recording engineer or adventurous home recordist could splice tape. I remember seeing punk rock band “mission of burma” and noticing that they had a “fourth member” mixing sound but also making live tape loops as they played and mixing it back into the songs. I can tell you he was thrilled when I noticed what he was doing!