JAZZ is metal.

Well, of course it isn’t, really. They don’t sound alike on their outer layers. And their audiences don’t overlap. From the evidence of hundreds of jazz shows I’ve seen all over the country this past decade, a whole lot of Americans over 60 feel a tremendous fondness for jazz and help it survive. Most of those same people, I’d guess, would feel a virulent loathing for metal, if they ever were forced to encounter it.

Currently, making it in jazz means playing a circuit of sit-down supper clubs and comfortable midsize theaters booked by nonprofit arts presenters, and, in summer, at European festivals. If you make it in metal, you play a circuit of decent-to-horrible stand-up clubs. (And, in summer, at European festivals.) The aesthetic ideals couldn’t be more different: jazz is about subtlety and, one wants to say, beauty; metal is about intimidation, alienation and assault.

But then again, over the last decade jazz and metal have become harder to reduce and easier to like, in a sum-total kind of way. And in the process they’ve generated more and more points of comparison.

Jazz stages and metal stages are places where a certain kind of experimentation happens: brainy and cabalistic, with a hint of a smile. Both increasingly depend on educated virtuosos. In both genres you can develop curious harmonic worlds, warp the tempos, brush against folkloric or conservatory music, play many notes very speedily and engage sturdy American grooves or a more studied system of fitting odd-number beats into even-number meters. Pat Metheny, jazz guitarist, meet Paul Masvidal of Cynic; Jeff (Tain) Watts, jazz drummer, meet Tomas Haake of Meshuggah. Both forms seem to have a neatly divided audience: maybe two-thirds respectfully fixated on the music’s past, one-third concerned about building paradigms for the future.