Air Museum is the fifth album by Mountains, a band that consist of two "sonic explorers" - their words not mine. Brendon Anderegg and Koen Holtkamp are prolific creators of challenging electronic musics both together as Mountains and on solo projects. They make leaps and bounds with each album and this one, more than the previous.

Air Museum is only seven tracks long, all clocking between 5 and 3 minutes long, and all are entirely instrumental. Mountains seek to explore texture and tone with their music, don't expect verse-chorus-verse, or even any discernible structure at all, other than linear progression. Think Fuck Buttons meets Jónsi & Alex; long swells of electronic processed sounds and pulsating bass, are covered in layer after layer of sonic excess, creating shifting and diverging soundscapes.

This album has one more thing in common with Jónsi & Alex's album Riceboy Sleeps; despite the synthetic seeming sounds that populate Air Museum, in fact they are predominately from acoustic instruments the processed through analog modulators and other external processing, before being recorded in the studio. Up till now, the duo had been creating entirely synthetic sounds with laptops for live shows, and recording these at home for LP releases, but this time we get real instruments and a real studio. This gives the tracks an organic feel despite the unnatural sounds. It feels grounded, purposeful and not just experimentation. One could imagine these songs not feeling out of place soundtracking David Attenborough-esque nature footage.

There isn't much variation over the course of the album, but at 43 minutes this isn't a problem. The attention to detail that is evident in every reverb drenched drone keeps your ears pricked, waiting to be taken in to Mountains' world. I can completely understand how most people could only appreciate this kind of music in the context of a soundtrack; not everyone can sit down and listen to music that is this abstract. But if you do fall into the category of people who can let go of expectations from an album and just listen, whatever comes out of the speaker-cones at you, this I think there is a really enjoyable experience travelling through Air Museum.