While both artists could well be filed under drone or ambient music Biosphere is perhaps more recognisable under those headings. Helge Sten's work under his Deathprod moniker might better be described as textural music. That's not to say records such as Treetop Drive or Morals and Dogma lack the wide panoramas of the best ambient music but to my ears Sten's work has always been more directly material, working with sound at the most basic raw level and building it up, often into quite oppressive and dissonant structures.

Fans of Biosphere's catalogue will find much to like with album opener Muses-C. The familiar electronic loops and gracefully shifting tones which made Substrata and Dropsonde classics of their type are revived here with no less pleasing results. Things get more interesting though with the appropriately titled Shimmer/Flicker, the first half of which bares the signature of Sten's subterranean drones drenched in reverb which here sound as if they are emanating from the centre of the earth. Vaguely metallic sounding, as if vast metal strings were being bowed,  they usher in the "flicker" part  of the piece where sudden bursts of sound dart in and out of the sonic gloom, illuminating briefly the void which was evoked during the first part.

Polychromatic and Disk are both shorter tracks where the collaborators signature styles are expressed most concisely. The latter is a particularly effective exercise in glacial drone and minimal glitching electronics. The tone pallet and sparse arrangements recall Biosphere's "arctic ambient" style, but with the intervention of Sten the elegiac mood is pulled into darker territory. It's still glacial in that somewhat clichéd fashion, but also haunted by a more human melancholy that prevents this music ever being described as meditative. Space is Fizzy is another aptly titled piece which pits more of Biosphere's chiming loops and subtle rhythms against the hiss and murky black texture of Sten's atmospheres. Probably the most lively track on an album which often evokes the cold metal stasis suggested by its title.

Optical is the last and longest track on the record. Here the sound is thoroughly stripped back leaving only the vast form of Deathprod's drone which builds out of the silence to slowly envelop the sound field like some huge planetary body passing by, sucking everything into its gravitational field. After the delicate combinations of the previous tracks this suffocating atmosphere and omnivorous tone is a little disappointingly predictable. Sten does this sort of stuff better than most, but with the possible counterpoint of Biosphere's sound world to hand finishing the album with a big slab of dense audio isolationism seems a poor choice. It signals a mixed record which while holding great promise and some stand out moments doesn't succeed in moving either artist out of their comfort zone.