By the time Jon Hassell became a revered figure – the kind of determinedly non-commercial, avant-garde artist whose ideas are so strong and so forward-thinking they end up influencing the mainstream regardless – he was already middle-aged, but had crammed a lifetime’s worth of musical experience into his 40 years. He had begun his career as a trumpet player in the swing era – tellingly, his own tastes leaned towards Stan Kenton, among the most progressive and experimental of the big band leaders – before becoming immersed in the cutting edge of modern classical music and moving to Cologne to study under Karlheinz Stockhausen: his fellow pupils included Irmin Schmidt and Holger Czukay, both later of Can. In an early example of his lifelong desire to meld differing musical forms, he began attempting to apply Stockhausen’s tape experiments to recordings of jazz vocal quartet the Hi-Los. On returning to America, he collaborated with synthesiser pioneer Robert Moog, minimalist composer Terry Riley and La Monte Young, becoming a member of the latter’s Theatre of Eternal Music, best-known in rock circles for acting as a kind of drone music boot camp that helped shape the Velvet Underground’s John Cale and Sterling Morrison. Hassell then moved to India to study raga under the classical singer Pandit Pran Nath. Again, Hassell became immersed in attempting to draw together two different musical traditions, applying the ornamentation of his teacher’s vocals to his trumpet playing, connecting Indian music with jazz, American film soundtracks, Yma Sumac and Ravel. One result of his study was his debut solo album, 1978’s Vernal Equinox, on which he fed his trumpet through electronic effects and adapted his playing so it frequently sounded more like a flute or a voice than a horn: you could detect echoes of raga, Young’s drone experiments and electric-era Miles Davis on its sound, but the result – calming, meditative, thick with the non-western influences suggested by track titles that included Blues Nile, Toucan Ocean and Caracas Night – ultimately sounded like nothing else at the time. It was the first flowering of what Hassell called ”fourth world” music, where a plethora of global sounds collided with technology to conjure what Brian Eno – who encountered the album while living New York, and quickly became Hassell’s most famous advocate and collaborator – later called “a globalised world, constantly integrating and hybridising, where differences were celebrated and dignified”. In time, and particularly with the advent of sampling, it would become a very pervasive idea indeed. Hassell’s early 80s work with Eno and with Talking Heads was not without its tumultuous side: he quit the project that became Eno and David Byrne’s lauded 1981 album My Life in the Bush of Ghosts early on, unimpressed, he said, by the music that was emerging. Nevertheless, he and Eno remained close friends and regular collaborators for the rest of Hassell’s life: those are Hassell’s effects-laden trumpet moans over the eerie soundscape of Shadow from Eno’s solo album Ambient 4: On Land; his extraordinary, haunting solos on Houses in Motion, from Talking Heads’ 1980 album Remain in Light, and on Fourth World 1: Possible Musics, a Hassell and Eno album also released in 1980, where African hand drums, drifting electronics and Hassell’s playing combined to create a heady, humid, utterly seductive mood. Their best-known work together led to Hassell becoming a session musician of choice for a certain breed of artistically adventurous 80s pop star: he played with Peter Gabriel, David Sylvian and Tears for Fears, among others, and became a regular contributor to Ry Cooder’s soundtrack work (Cooder reciprocated by regularly performing on Hassell’s albums). He kept developing his notion of fourth world music – the dense polyrhythms of 1986’s Power Spot, produced by Eno and Daniel Lanois, is a particularly compelling listen – as well as expanding his sound in different stylistic directions. From 1990, City: Works of Fiction was influenced by hip-hop and sample-heavy dance music. Dressing for Pleasure, from 1994, boasted an impossibly eclectic supporting cast – Red Hot Chili Peppers bassist Flea, celebrated jazz saxophonist Kenny Garrett, sometime Guns N’ Roses guitarist Buckethead and Greg Kurstin, later to become a pop super-producer – and almost qualified as trip-hop. It said more about Hassell’s influence on the more exploratory aspects of dance music than it did about any desire on his part to chase trends. While he had obviously presaged the atmospherics of “chill-out” music and sample culture’s kaleidoscopic melding of disparate music influences, rather than capitalise on his influence, he headed deeper into jazz territory, interpreting standards including Nature Boy and Duke Ellington’s Caravan on 1999’s Fascinoma. Hassell seemed equivocal at best about his impact on pop. Contemporary producers were clearly inspired by him – you could hear echoes of his sound in the Aphex Twin’s Selected Ambient Works Volume II; he was lauded by everyone from Björk to Bono, sampled by minimal techno hero Ricardo Villalobos and avant-garde auteur Arca alike and was eventually given his own record label by pioneering electronica imprint Warp. He worked with DJs Howie B and Carl Craig, but decried what he called “the banalisation of the exotic … the herd trampling through the campsites where I delicately and respectfully visited 15 or 20 years ago”. When asked by a website to list his favourite music, Hassell declined to include any “ethnic favourites” as a result of “Deep Forest-like appropriation”. “I feel,” he protested, “like a mother bird whose babies have been touched by humans and don’t want to have anything to do with them any more.” It was a complaint with a serious point at its core. Cultural appropriation became a hot topic, but Hassell avoided such accusations. He gave lavish credit to his sources and collaborators; as Eno put it, “one overriding principle in Jon’s work [was] that of respect – he looks at the world with all its momentary and evanescent moods with respect and that shows in his music”. Last summer, I interviewed Hassell for the Guardian. He was, by his own admission, in a depleted state. He was 83, he had broken his leg after a fall in his studio, and spent four months convalescing in hospital without visitors, as a result of the coronavirus pandemic, “so I only had my cellphone to retain contact with the outside world”. It seemed a cruel fate for someone who had spent their life immersed in the world’s music and culture in all its multifarious forms. He didn’t know whether he would be able to play the trumpet again, but, for all his travails, he remained filled with ideas. He explained his self-devised concept of musical “pentimento”, which had informed his last two albums: dense shifting sound collages, where “layers of corrections are used to effloresce out something”. He talked about a theory that underpinned an unpublished book he had written, concerning the battle between the intellectual and the Dionysian impulses in music. “I have plans,” he laughed, but then, Jon Hassell always did have plans: he planted seeds, Eno once said, “whose fruits are still being gathered”.