AUN is definitely the work of Christian Fennesz, but it does have a distinctly different sensibility compared to the work he normally puts out under his surname. Rather than a suite of complex, evolving compositions, this feels more like a series of sketches, a rough draft for other works, that function just fine on their own (and obviously work well in a soundtrack context).
A quick look at the track listing makes this rather quickly apparent: 15 tracks, many of which clock in at under three minutes. While Fennesz is not as prone to sprawling, epic length compositions, his work usually consists of longer pieces than this. Some of the exceptions are the three tracks carried over from his recent collaborative album with Ryuichi Sakamoto, Cendre ("Aware," "Haru," and "Trace").
It also makes sense to have these shorter, barer pieces as part of a soundtrack rather than his usual rich, nuanced compositions. There is no doubt who is responsible for this material, from the gauzy, shimmering noise of opener "Kae" to "AUN40", the latter of which's ghostly melody and fragmented tones bear his unmistakable mark, although the closing half stretches into darker, bleak lands that are a bit out of character.
That sun-faded, nostalgic sensibility of Fennesz's best work also shows up on "Nemuru," which, especially due to its building complexity in the second half of the track, would not be out of place on a traditional LP from him. The same goes for "Nympha," which balances delicate synthetic textures and untreated guitar playing. Albeit sparse, the heavily processed, bitcrushed guitar and unidentifiable sounds on the brief "Mori" sound like a brief fragment of a longer purely album-oriented Fennesz work.
It is on pieces like "Sekai" and "Himitsu" where the disc feels less like finished work. The stuttering acoustic guitar on the former song and the digitized textures on the latter are quite compelling on their own, but make up the bulk of mostly threadbare, short tracks. "AUN80" is the only time where this feels like a problem: the erratic guitar and dissonant bass noises feed into an ugly, messier sound that I have not heard from him too often, and thus I would like to hear more of this approach, but alas the piece is limited to only a few minutes.
I would not be comfortable calling this a new Fennesz album, given the structure of this disc, but it is not being marketed as such. It lacks the lush complexity of an Endless Summer or Black Sea, but for those works to be used in a soundtrack capacity, I think they would draw too much attention away from the film, which should never happen. Instead this album is one that compliments visuals, but also manages work well on its own. It still comes across as more of a series of demos and sketches, but it remains a quality work nonetheless.