For many people, the term “free improvisation” probably conjures ferocious torrents of sound. The quartet Bolt takes a gentler path. The spontaneous collective improvisations of alto saxophonist and lyricon player Jorrit Dijkstra, guitarist Eric Hofbauer, cellist Junko Fujiwara, and drummer Eric Rosenthal invariably have a transparent texture that belies their open-ended method. And somehow, despite the lack of fixed meters, chord progressions, or tonality, the band is able to suggest a form for each piece: something post-serialist composers struggle to do with a lot of hard writing. Credit each player’s innate compositional sense, attentive ears, and quick reflexes. The mixture of jazz phrasing and seemingly random clicks, whirrs, squawks, pops, and plucks takes on a lyrical delicacy. (At times, Dijkstra and Hofbauer suggest Jimmy Giuffre with Jim Hall.) The CD presents 19 pieces in barely more than 47 minutes (the shortest at 37 seconds, the longest 8:09), most with rhyming (or slant-rhyming) one-syllable titles (“Lace,” Haze,” “Trace,” “Blaze”). As if to further randomize their approach, a note on the CD suggests that you play the CD in the mode of its title. (Out now.)
Bolt plays Third Life Studios, Somerville, Saturday at 8 p.m.