Two years ago, at the nadir of the financial crisis, the urban sociologist Sudhir Venkatesh wondered aloud in the New York Times why no mass protests had arisen against what was clearly a criminal coup by the banks. Where were the pitchforks, the tar, the feathers? Where, more importantly, were the crowds? Venkatesh’s answer was the iPod: “In public spaces, serendipitous interaction is needed to create the ‘mob mentality.’ Most iPod-like devices separate citizens from one another; you can’t join someone in a movement if you can’t hear the participants. Congrats Mr. Jobs for impeding social change.” Venkatesh’s suggestion was glib, tossed off — yet it was also a rare reminder, from the quasi-left, of how urban life has been changed by recording technologies.

The concern that recorded music promotes solipsism and isolation isn’t new. Before the invention of the record and the gramophone (1887), the only form of listening people knew was social; the closest thing to a private musical experience was playing an instrument for yourself, or silently looking over a score. More often, if you had the means, you got to sit in the panopticon of the concert hall, seeing and being seen to the accompaniment of Verdi — an experience most fully described by Edith Wharton in the opening scene of The Age of Innocence (1920), just as it was going out of style. With mechanical reproduction came the hitherto unimaginable phenomenon of listening to multi-instrumental music by yourself. How, a contributor to Gramophone magazine asked in 1923, would you react if you stumbled upon somebody in the midst of this private rapture? It would be “as if you had discovered your friend sniffing cocaine, emptying a bottle of whisky, or plaiting straws in his hair. People, we think, should not do things ‘to themselves,’ however much they may enjoy doing them in company.”

If solitary listening suggested to some people a scandalous analogy with other forms of self-pleasure, it led others to proclaim the emancipation of music from the vagaries of performance and the distractions of the visual. Even stodgy Adorno praised liberation by vinyl: “Shorn of phony hoopla, the LP . . . frees itself from the capriciousness of fake opera festivals.” Lighting a joint, the narrator of Invisible Man (1952) discovered a “new analytic way of listening to music,” which revealed to him the layers of racial meaning embedded in the melodic flights of Louis Armstrong’s cornet. (Jazz, though principally an art of live improvisation, fed on its own recordings, which captured nuances of rhythm and timbre, pitch and dynamics, better than notation ever could, such that Max Roach would later declare records to be the “textbooks” of jazz.)

But it wasn’t only solitary hyper-listening that recording facilitated. By 1960, recorded popular music had begun, in mysterious ways, to promote new social movements. Former Black Panther Bobby Seale recounts in his memoir how Huey Newton developed an elaborate reading of Dylan’s “Ballad of a Thin Man” as an allegory of race: “This song Bobby Dylan was singing became a very big part of that whole publishing operation of the Black Panther paper. And in the background, while we were putting this paper out, this record came up and I guess a number of papers were published, and many times we would play that record.” The song wasn’t overtly political but its mood of stately menace seems to have insinuated itself into the politics of the Panthers.