Natural Information Society's fifth album since forming in 2010 – and its second double-album, following 2015's equally expansive Magnetoception – finds the Chicagoan outfit convened as an all-acoustic eight-piece, pursuing more deeply than ever its signature brand of spiritually charged ecstatic minimalism. It's possible to view percussionist Hamid Drake as a totemic figure within this band, representing a link to Don Cherry's Organic Music Society, with whom he played in the early 1970s. The two central jams on the new album – the 24-minute ‘In Memory's Prism’ and the 40-minute ‘Finite’ – are both based around deep guimbri trance riffs that slowly unfurl like soporific dream cousins to Cherry's ‘Brown Rice’, borne along by basic hand percussion and twinkling harmonium drones. On the former, sustained horn notes waft in and out of focus, while the latter unfolds to reveal flecks of piano, allowing mellow horn solos to emerge gently. These long, unhurried explorations more closely resemble Natural Information Society's live shows – but the two shorter tracks allow them briefly to explore other moods: the 12-minute ‘Shadow Conductor’ is a contusion of juddering eighth-notes, while on ‘Agree’ every member of the band takes up a wooden flute for six minutes of fluttering jungle collage. Sincere, serious and deeply transporting in equal measure, Mandatory Reality deserves your attention.