The three-letter term IDM, for “intelligent dance music,” is used often enough to describe a broad array of music, from Aphex Twin’s jerky ambience to Kid606’s digital acts of agitation. Another three-letter word, ECM, as is the estimable label ECM Records, run by producer Manfred Eicher, might lend itself to a more precise subset of electronic-oriented recordings — music that is compositionally open-ended, and whose deeply sedative aspirations are not technologically dependent. Drummers as fit as Joey Baron and Tony Allen likely couldn’t play two-hour equivalents of drum’n’bass if their lives depended on it; the music, with its high-wire feats of metrical aggression, pretty much requires a machine to make it happen — not that there’s anything wrong with that. However, there is a brew of quietness, of soulfulness, that is as sure to echo from Bill Frisell’s deeply digitized guitar as it is from Arvo Part’s a cappella chorus. The band Rothko makes this sort of music, and its new album, A Continual Search for Origins, with a mix of softly intoned instrumentation and documentarian field recordings, evokes a spirit of profound reflection. The field recordings were made by Rothko leader Mark Beazley, who taped various background sounds during a trip to Switzerland. In the album’s brief liner note he explains that those raw tapes became the “starting point” for a variety of instrumental settings, including percussion, sleigh bells, trumpet, guitar and much more. The first and last track feature prominent vocals by Caroline Ross, who sings plaintively over the slow tide of music. Nine tracks in between overlay delicate compositions on top of sounds of rain, wind and, again, according to Beazley’s note, “the sound of just sitting quietly.” The album was released on the label Too Pure on June 4, 2002.