It's avant-jazz night at the Firefly, so what is the klezmer band Into the Freylakh doing on stage? Isn't klezmer, with its roots in medieval Eastern Europe, the music my great-grandparents probably danced to at their wedding in the old country? Doesn't the intricately ornamented melody spinning out of bandleader Bryan Pardo's clarinet echo the vocal improvisations cantors have chanted for ages in synagogues from Budapest to Brooklyn? Isn't "Rebbe Elimelech," the Yiddish equivalent of "Old King Cole," which Jennifer Goltz is gleefully belting out in her sparkling soprano, so old that only musicologists can trace its origins? This is cutting-edge music?

But listen some more. Even on the most familiar songs there are surprises — composed interludes when Into the Freylakh is no longer following the standard form of improvising over repeating choruses. And check out the complex jazz/classical influences in the long, look-Ma-only-two-hands! piano intro that Isaac Schankler fashions for the simple Israeli folk song "Ma Navu." Or listen to Pardo introduce one of his original tunes, titled after his favorite Star Wars character, by suggesting we repeat the phrase "Chewbacca wookie, Chewbacca wookie, wookie," over and over to stay in rhythm with the music. Then there is another Pardo original, "Spanakopita," also in an unusual meter. Klezmer in seven? Try dancing the kazatski to that!

But lest you think that this is academic, brain music, just tune into Gabe Bolkosky's deeply expressive solo on "Ma Navu." You find yourself leaning forward, almost expecting to understand the notes, as though the violin were calling to you in your mother tongue. And later you find yourself singing along with him on the "Der Audience Participation" song, finding that yes, you can scat sing in Yiddish! Then there are the dazzling exchanges between Pardo's clarinet and Bolkosky's violin, bringing to mind an imaginary 1930s jam session with Benny Goodman and Stephane Grappelli. If the Firefly had a dance floor, we'd all be on our feet, stomping out a grapevine to "Mayim." Lacking that, we sway in our seats, pounding our heels, rhythmically clapping with drummer Michael Gabelman and bassist Andrew Ktratzat's syncopated klezmer beats.

As eclectic as all this sounds, Into the Freylakh is, actually, solidly in the klezmer tradition. Klezmer has always traded with the musical cultures that surrounded it. The klezmorim of old listened to the folk and classical music of Eastern Europe. Immigrant klezmer musicians, transplanted to the New World in the early twentieth century, listened to Tin Pan Alley, Dixieland, and swing. Today's klezmer practitioners are often conservatory trained (all the members of Into the Freylakh are current or former U-M music students) and listen to modern classical composers and Coltrane.

Freylakh, in Yiddish, means "joy." Into the Freylakh, whatever it's playing, dives into that joy and invites you to join. The New York subways used to have bakery ads that read, "You don't have to be Jewish to love Levy's," and you don't have to speak a word of Yiddish, or have grandparents from Galicia, to be moved by this music.

Avant Tuesdays have been discontinued at the Firefly, but you can hear Into The Freylakh there on Thursday, March 6.