The idea of deep or detailed listening is a useful one because it’s purposefully vague. That vagueness comes in part from being understandable without needing to route it through a definition. It’s also rich enough in connotation to suggest a whole lifestyle. The idea of detailed listening is not the same as Michaelangelo Matos’ slow listening movement, but they seem to share the same spirit of deliberateness and presence. Mountains, the Brooklyn duo of Koen Holtkamp and Brendon Anderegg, make music intended for undrifting attention, but their music has never had the built-in punishment that some, more academically oriented drone music employs to prevent their music from becoming furniture. So, if you’re intent on criticizing Choral, Mountains’ third LP and first for Thrill Jockey, you would probably take exception to the album’s prettiness. It’s easy to let these 51 minutes slip by without making much of an impression apart from an undulating, general warmth, like some kind of aural space heater. But then you’d have to be pretty skilled at exclusively peripheral listening; prettiness can’t prevent music this good from unexpectedly colonizing your attention. Not vulgar enough to make the coup with a shift in volume or tone or the abrupt introduction of a melody, Mountains proceed by stealthy, deliberate layering. The album opens with a drone that ebbs out to reveal lovely fingerpicked acoustic guitar harmonies that know well enough not to linger; “Telescope” reverses the syntax by establishing a gallant-sounding, square-jawed strum before fading in slightly dissonant, thrumming counterpoint, as effective a foil as vinegar in banana muffin batter or the detuned keyboards in “Single Ladies (Put a Ring on It).” But that’s among the album’s most obvious transitions. Subjected to real-deal deep listening, Choral is a very producerly album, with new elements constantly emerging, old patterns reducing down to a savory broth to accommodate fresh textures. It sounds like a protean stew, but the music is never busy, not quite. It’s just that when you get up close you can make out all these heretofore-unseen entrances and exits, each one totally unfussy and unselfconscious, as good TV actors performing a good script might do. The elements Holtkamp and Anderegg use on Choral seem touched by anonymity when compared with last year’s solo outing from Holtkamp, the much-beloved and late-blooming Field Rituals. The field recordings and instrumental passages (instrumental meaning not “without vocals” but “parts where a recognizable instrument is playing a riff”) on that album made for chunkier pairings, culminating in the sparkle-drone “Haus und Spirale im Regen.” Closer to a true drone than anything on Choral, “Haus” verged less on stasis than a mild but keen claustrophobia, a meditation that makes you keep forgetting to breathe. In collaboration with Anderegg, that intensity levels off, with the music itself coming perceptibly closer to folk, or more accurately, closer to an exploration of the sonic ingredients of folk, plus a healthy love of dub and melodicas and dosed with the breadth of The Well-Tuned Piano. The only thing that detracts from the accomplishment of Choral is its proximity to Field Rituals, but it’s nothing to do with one of the album’s superiority over the other, just a matter of each throwing the other into better relief. And, really, that’s only bad inasmuch as it’s the only thing that distracts from the involving, detailed beauty here. There are many musicians working in this vein, but Mountains spew a pitch-perfect combination of earthiness and abstract bliss with astonishing ease. Like good yoga, every second is different with this kind of drone. - By Brandon Bussolini