On Rendlesham Transmitter, UK sound art and research project Coagulant follows up their superb previous release Anamorphoses with another set of deeply immersive abstract soundscapes. The approach to sonic processing they adopt is once again pleasingly aggregate, with spacious room recordings and airflow drones melding with distant voices and clatter to create opaque, mysterious currents of sound—the elements all truly “coagulate” into something new. For me, Coagulant’s music is difficult to elucidate because it is so unavoidably holistic; just like the complex psychological processes it attempts to examine, each piece the project generates unfolds as an inseparable whole, the multitude of ingredients that constitute them always bound within a dense knot of relationships. This quality provides an explanation for why each track is able to draw so much from what is essentially stagnancy (on “DMT Entities” especially, not much changes throughout its nearly 24-minute duration, yet “boring” or “repetitive” are the absolute last words I would use to describe it); the listener spends their time constantly attempting to decipher that tangled web of inextricable relations, trying in vain to isolate each component in this congealed amalgam of auditory uncertainty. As background music, Rendlesham Transmitter is meditative, nocturnal, murky; as focused listening, it’s an impenetrable clump of sound that we’re constantly trying to break open, but all we can really do is perceive it from different angles and futilely try to convince ourselves that we have it all figured out.

Amazingly, it’s been over a decade since the last full-length release from Belgian improvisational group R.O.T., whose public and internet presence is as elusive and obscure as the music they create. Klein Eiland is an album heavily indebted to location; all ten pieces contained on the CD were recorded in a now-demolished Brussels building of the same name, and the quartet’s abstract textural interactions reverberate through its spacious rooms and halls before disappearing into the dark, spectral void that lurks just beneath our perception. Improvised music and documentation have always been locked in a knotty, even contradictory relationship; purists insist that the identity of an improvisation is hinged inextricably on its taking place in real time, and that recording it creates something entirely distinct. These issues are complicated even further on Klein Eiland—not only was the location where it was recorded demolished, but something entirely new now stands in its place (an apartment complex which is pictured on the back of the CD sleeve). But the skilled sound artists who perform as R.O.T. have somehow managed to evoke that profound reality of impermanence even in this timeless document: the ghostly electronic transmissions, sparse concrete interplay, and distant instruments are somber, elegiac, fleeting, breathtaking in how they fill these mysterious spaces yet dissipate just as quickly. I’m reminded of similarly environment-dependent improvisations like the Battus/Gauguet/La Casa Chantier series or Akio Suzuki and Aki Onda’s KE I TE KI, but Klein Eiland is singularly sublime and harrowing, and evokes something that’s at once material and completely intangible.