- The smooth, bluesy tones which kick off Sparrow Nights could be mistaken for a jazz standard, but what comes next is anything but. Peter Brötzmann is at the tail end of a fifty year career, one that has taken him to the outer edges of improvised music. But during this final chapter, he seems to be coming back down to earth, eschewing large, noisy ensembles in favour of close and intimate collaboration. Intimate really is the word here, as Brötz is joined by steel pedal guitarist Heather Leigh for a collection of tracks which toe the boundaries between ambient and abrasive.

For most of Sparrow Nights, Heather takes a firm backseat role, weaving majestic ambient backdrops for Brötzmann to slowly unravel. The textural scope and depth Leigh manages to bring out of her instrument is remarkable, moving from glimmering sheets of sound on River Of Sorrow, to intensely oscillating harmonics on At First Sight. The simple chord progressions which underpin most songs feel like they could disperse at any instant, falling in and out of hypnotic cycles to craft an unstable yet compelling atmosphere.

The project's fluidity makes it hard to pinpoint standout moments, but a good starting place would be This Time Around. The piece opens with a pattern of strained guitar tones landing somewhere between shoegaze and harsh noise. Brötzmann enters with overpowering shards of sound, stretching Heather's backdrop as the duo drive each other forward. Sax stabs become increasingly manic, riffs distorted further still and things start to collapse. Peter's impassioned cries soundtrack an apocalypse, slowing tempo to a tortured crawl. Each piece is a constant push and pull between the duo, progressing ever forward as they gracefully evolve harmony and texture.

This is only the latest in a series of collaborations between Brötzmann and Leigh, but it already feels like their most complete. The duo's previous live releases were fascinating explorations of sound, but Sparrow Nights is more varied, focused, and full of ideas than any of them. Each track makes an effort to differentiate itself, go somewhere new, or explore yet another facet of the duo's endless interplay. This is best shown on long cuts, where these ideas are given adequate time to naturally unfold across ten or more minutes.

Heather and Peter take turns soloing on It's Almost Dark, while their performances collide in the track's middle. It's a great showing of what each member brings individually; Leigh showing her folk roots with meditative and subtle progressions while Brötzmann channels Eric Dolphy in his off-kilter melodies. I'm starting to understand what Peter sees in Leigh as a improv partner, as her style takes him somewhere new. While the man is no stranger to one-on-one collaborations, his past work with Hamid Drake or even the late Sonny Sharrock has seen the pairs forcing each other further into chaos. With Heather it's almost the opposite, the two provide ample space to explore the calmer side of their playing, and it works wonders.

Sparrow Nights isn't going to be for everyone. It's a horrible place to start with jazz, and there are probably better options for Peter and Heather's respective catalogues. But if you know your way around improvised music and want to hear two masters of their craft engage in a series of fascinating musical conversations, then there's a lot to be found here. You can hear the imperfections in Peter's breath technique, feel Heather's sudden impromptu chord shifts. Simply put, it's a record that sounds alive.

- Boddhi Farmer.