According to the usual histories, the influence of African music on what became known as jazz was assimilated so thoroughly that only a few obvious "retentions" survive. Primitive drumming sessions by slaves in New Orleans' Congo square soon gave way to the civilised sounds of European brass band instruments, an excess of which had conveniently become available following the end of the Civil War. Before you knew it, the by now freed slaves were playing polkas and gavottes, converted by the addition of those African-ised blue notes into something approaching jazz. Yes, the rhythmic base of the new music might derive from Africa, or African-American slave culture, but the superstructure of melody and harmony - the real complex stuff - belonged to the United States and Europe. Or so the story goes.
But you try telling that to the guitarist Bill Frisell, who is touring the UK with the African guitar player Djelimady Tounkara, founder of the famous Super Rail Band of Mali. For Frisell, 52, who is perhaps the most important jazz musician of his generation, playing with World Music Award-winner Tounkara involves an immersion so deep it cannot be fathomed. "I've loved African music almost as long as I've been into jazz," he told me from his home in Seattle. "There was this record of kora music that I loved, with this real mystery about it, and later in England I heard a cassette of Ali Farka Toure. I feel lucky just to get the chance to play with Djelimady, but I still don't really understand it; or rather I understand little bits. He'll show me some kind of simple basic thing and then we start playing, but the level of invention that goes in on top of that is extraordinary to me. I don't think I can ever get very far into it."
Frisell laughs at the notion that jazz represents some kind of refined essence of Africa's raw material. "Over here, they have this simplified version of how jazz developed, but it's just not as one-dimensional as that. There's a lot more to and fro, and back and forth. Also, their music is so advanced, the levels on which they can keep some underlying thing going; it just keeps getting more and more complex. Even if your attention is all in one place, like it's simple, with maybe only one chord, you begin to realise how many levels there are. The more I find out about it, the more complicated it gets." Does that mean, I ask, that we are talking about different musical languages? "Not really. Music is sort of one big language," Frisell says. "All that stuff melts away when you start playing; it's possible to fit almost everything together in some way." Over the 30 years of Frisell's professional career, he's managed to fit most things together, from Hendrix-derived rock and squeaky-gate contemporary classical music, to pure-as-springwater bluegrass and country. His most lasting legacy, however, is not so much a type of music as a specific sound: the pedal-driven atmospherics that have become his personal signature, to be heard not only on his own peerless series of recordings for the Nonesuch label, but also on sessions for Elvis Costello, Marianne Faithfull and many others. Originally influenced by the "ambient" records of Brian Eno and Robert Fripp, Frisell's delicate textural effects - a kind of aural weathering - have now entered the standard vocabulary of jobbing guitarists everywhere.
Frisell's other great accomplishment is the way, like Picasso, he's managed to maintain a coherent artistic personality while continually changing styles and settings. Thus, in 1997, after more or less defining the left-field sound of New York's Lower East Side jazz avant-garde, he released the classic "Nashville" album, swapping his Klein electric guitar for a fat-bellied acoustic to pick bluegrass-influenced numbers with a band borrowed from Alison Krauss's Union Station. His latest project, prior to the current tour, is a new multi-cultural band, The Intercontinentals, which brings together musicians from Greece, Brazil and Mali. Pedal-steel guitarist Greg Leisz, violinist Jenny Scheinman and percussionist Sidiki Camara from The Intercontinentals also form the band for the Djelimady Tounkara tour.
"So far, I've not given up anything," Frisell says, when I ask him whether mixing musical registers involves a lot of compromise. "You've got to go out on a limb and see how far you can go; it's an incredible learning thing and that's how I grow. Maybe I change too much but I like to put myself in new contexts. To experience that feeling when you connect for the first time, is amazing. It's all good. Or maybe I change less than the context; I just do the same thing while everything around me is different." Frisell's success with collaborative projects must also have something to do with his personality. Born and brought up in Denver, Colorado, he has a westerner's open demeanour combined with a delightfully shambling, "Ah, shucks" air. When he speaks (and mostly, he doesn't), it's like Gary Cooper: slow and spare, the thoughts punctuated by quiet exclamations of "Gee" or "Oh boy". Asked about the experience of playing with Tounkara, with whom he performed at the Barbican last year, Frisell becomes unusually animated. "Oh boy. When we first met he asked me to play something. Someone said 'Wildwood Flower', this old folk song, and he nodded his head and we started to play. You think that it's American country music or whatever and he's playing ancient African music, but it was the same thing: it's all coming from the same place."
Bill Frisell plays the Barbican, London EC1 (020 7638 8891), tonight; CBSO Centre, Birmingham (0121 780 3333), Mon; Opera House , Newcastle (0191 232 0899), Wed; West Yorkshire Playhouse, Leeds, (0113 213 7700), Thurs; Corn Exchange, Cambridge (01223 357 85), Fri; Dome, Brighton (01273 709 709), Sat; Colston Hall, Bristol (0117 922 3686) 7 March