Tabadol is Arabic for “exchange.” That’s what bass clarinetist and former Chicagoan Gene Coleman had in mind last year when he arranged for members of Lebanon’s nascent free-improv scene to visit five U.S. cities and perform with local musicians and visiting Europeans in each. While the plan seemed potentially intriguing from a political and cultural angle, I was looking forward to hearing the music; bassist Raed Yassin, trumpeter Mazen Kerbaj, and saxophonist Christine Sehnaoui are all strong players whose use of extended techniques and preference for harsh textures owe little to either jazz or traditional Middle Eastern music. But just before the tour could start, Israeli planes bombed the Beirut airport, forcing the project’s postponement. Since then Kerbaj–whose label, Al Maslakh (“the slaughterhouse”), has released several impressive documents of the Beirut scene’s uncompromising approach–has taken to the Web to make powerful artistic statements against the war: on his blog he posts vivid, often brutal cartoons depicting the conflict’s ruinous effects and his attempts to cope with them, and elsewhere he’s put up an MP3 of “Starry Night,” in which he plays defiantly while bombs drop all around and car alarms sound in their wake. Tonight’s concert brings Kerbaj, Yassin, Sehnaoui, her guitar-playing husband Sharif, and oud player Ziad El Ahmadie together with Coleman, cellist Marina Peterson, and Italian percussionist Fabrizio Spera. See also Saturday and Sunday. a 8 PM, Renaissance Society, University of Chicago, 5811 S. Ellis, 773-702-8670. F A