John Cage wanted to dissolve the boundaries between art and the ordinary world by blurring the differences between music and noise; an ideal that, as it is well known, was embraced also by his Fluxus pupils in other artforms. Yet, it is not clear to me what exactly Cage’s ultimate aim was: whether to reduce art to ordinary objects or to elevate everyday sounds to the status of music.
On the one hand, he maintained, music should not convey any meaning. Music must be pure sound. Moreover, music shouldn’t be melodic, for it is the resposability of the artist—he said—to hide beauty. In this sense, we might interpret, he wanted to reduce music to ordinary sounds/noises.
On the other hand, the way in which he called attention to the sounds of everyday life was by awarding them a place in rituals traditionally restricted to Music. Sound, then, we could think, should be as 'noble' as music, and it deserves to be heard as music currently is; we should be able to appreciate the richness and the (aesthetic?) interest of noise/sound.
It seems to me that Cage's real aim was the former, at least if we take his writings literally. Yet, what he really did was the latter. After all, placing an ordinary sound in an extra-ordinary context as the music theatre—as placing an ordinary object like a urinary in a museum—conveys certain meaning to the sound piece and certainly changes its character.
In any case, this doesn’t really matter much. You may think, as the audience that laughs in the video, that this is just a nonsensical whim of an eccentric artist. But, like it or not, Cage opened a place for sound and noise in music. Before, music, at the most, just imitated sounds, but after Cage—and the advent of electronic music—we hear everyday noises in all types of music from soundtracks to Manu Chao.