“Typewriter jazz” is an accurate description of both the content and the form of Allen Ginsburg’s Howl.
As an integral part of the Beat generation, Allen Ginsburg’s approach to writing poetry and the ideas he discusses are greatly influenced by the by the likes of Jack Kerouac, William S. Burroughs, and Lawrence Ferlinghetti (among others). All of these Beat generation writers explored spontaneity and an open flow of emotion much like that of an improvisational Jazz artist. In fact, Jazz is often cited as a primary influence on the Beat generation.
The form and structure of Howl could also be described by the phrase “typewriter jazz.” Early criticism lead Ginsburg to attempt to write with more spontaneity and emotion as well, as though he was literally sitting down at a typewriter and allowing the ideas just to wash over him. We see this in the poem’s long, run-on sentence type lines that spill over from line onto the next. The structure of the poem suggests a hurried, frantic pace that if we imagine coming from an old manual typewriter might indeed sound like jazz.