Improvisation is a tricky subject in hooks study because it can be taken as opposing the whole hook premise of wanting to hear a certain bit of music again and again. That’s so reifying, and tame! Improvisation is free and adventurous and has to be appreciated in the moment. The sense of it is “Oh! Look what we’ve found!” Once that’s happened, can you go back to being free and surprised that way again?
Sometimes, yes. Maybe.
Let’s be clear that we might be talking about improvisation on any of three different levels. How deep a freedom do you want? Or what combination of freedoms? (For there can be activity on any level at almost any time—or feints toward it.) Do you want it to be freshly decided (1) what one of a song’s parts is to be, like its melody? Or (2) what the song itself is to be? Or (3) what music itself is to be?
Improvisation-1 is free playing where it’s understood that we don’t know just which notes will be played or how. Freedom at this level pervades all live-performed music, even when it’s closely controlled (Charles Mingus told his band members to play every note on his score as if they had just thought of it themselves). But sometimes the music is organized to highlight someone’s relatively freer playing. The variable is often the phrasing or notes of the melody. Even though we know in general which notes are likely to be heard, a great improviser-1 can give us surprising jolts. Listen to Jimi Hendrix at Woodstock improvising beyond the normal bounds of a guitar solo in the instrumental break of “Purple Haze” and then playing some unexpected notes within the main theme when it returns:
At the next level, Improvisation-2 is free playing where, for the moment at least, no one knows what the song structure is. For example, a long Grateful Dead improvisation can put us in a state of relaxed expectations so that when a salient event occurs, like the intense tutti around 4:15 in the 2/27/69 “Dark Star,” we can’t say how it came about—and it has this quality every time we hear it. For a quite different level 2 experience, listen to Hendrix quickly flitting from one possible song to another in his “Woodstock Improvisation”:
All the way down, Improvisation-3 is free playing at the level of deciding what constitutes music itself at that moment. You can’t assume there will be any familiar song structure. There will probably (though not necessarily) be unmistakeable markers of “outsideness” like atonality or suspension of regular rhythm. There may be a vivid sense of primary sound-making actions that aren’t inherently musical but are being claimed for music.
I would say that Hendrix is exploring new versions of music on level 3 in the midst of his “Star Spangled Banner” improvisation, especially between 1:23 and 2:40.
Don’t settle for commentary that treats these sounds as music-painting of the Vietnam War or American social chaos, even if they are rather overwhelming in that aspect. They are Ur-music. The best hooks for me include the passage between 2:13 and 2:25, maybe because it comes so close to a simulation of warfare. Its own swooping shape is so musically beautiful that it can be snatched from the jaws of description. This quality is wonderfully confirmed in 2:30 to 2:40.
It’s unfortunate in a way that the whole improvisation-rich Hendrix performance at Woodstock is burdened with being emblematic of the Woodstock moment in American history. We use it as a reminder of “what was going on.” And Hendrix himself was not unwilling to talk about his playing as a reflection of his world. But the freshness of the improvised music, heard as such, pulls it free from anything else. It’s the soundtrack primarily of itself.
I must admit that right now the temptation is very strong to conclude by loading up Hendrix’s improvisation with cultural baggage all over again. You can see it coming. “This is our democracy, this is the paradigm of public action: seeing what we can come up with! This is what it is to live in the home of the brave and the land of the free: creative adventure (as opposed to holing up with guns)!”
No, I won’t do it. Just listen to the music, as it comes pluming out of that vent in the center of being.
Improvisation on drums is an interesting test case for the three-level model. In the ordinary course of things a drummer is free to improvise like mad all the time at level 1, because the drums have their own nontonal sounds that don’t interfere with anyone else’s notes or chords. At the same time the drummer is required to maintain a song’s rhythm and tempo and hit its beats very precisely. Almost the only way to free the drummer from this slavery is to make the rest of the band stand down for a drum solo.
A drum solo in a rock context is almost sure to involve improvisation at level 2, since the drummer has been freed from playing a particular song. The drummer will compose fresh song-equivalents and show virtuosity and taste by improvising-1 in those improvisation-2 structures. It is hard to imagine entering level 3, though, because a drummer is always heard as composing with very gettable rhythm patterns. To play “outside” (or “all the way down,” using my depth metaphor) would require more weirdness of sound or use of silence than is likely to be acceptable in a rock context.
Consider the most celebrated of all drum improvisations in rock, John Bonham’s solo in “Moby Dick” in Led Zeppelin’s Royal Albert Hall concert of 1970. It is definitely virtuosic improvisation-1 while exploring a series of fresh structures on level 2. But what do you think about level 3? How about when he comes to a profound pause at 5:12 and starts playing with his hands? Isn’t he quite radically deciding what music will be? Are such moments comparable to the most radical parts of “Star Spangled Banner”?
 “[Dennis Smalley in Spectromorphology points to] a primary level of sound-making gestures that are not yet musical – such as scratching at a piece of wood or rubbing two stones together. This is so tactile, so visual, and so proprioceptive – as if one’s own muscles were making the movements – that it becomes, in my view, part of a continuum of human gesture that is not limited to sound-making activities, but is defined, rather, by its quality of eliciting a spontaneous response in us in whatever sensory mode. Because these primary gestures are not specifically sonic, and to distinguish them from those that are, I shall call them non-sonic”—Tim Hodgkinson, “Does Free Improvisation Have a Future?” (2010).
 Al Aronowitz claimed that Hendrix’s “Star Spangled Banner” “was the most electrifying moment of Woodstock, and it was probably the single greatest moment of the sixties. You finally heard what that song was about, that you can love your country, but hate the government.” Quoted in Charles R. Cross, Room Full of Mirrors (New York: Hyperion, 2005), p. 271.
 “We play it [‘Star Spangled Banner’] the way the air is in America today. The air is slightly static, isn’t it?”—United Block Association press conference, September 3, 1969.