I've been listening to "Caravan" a lot lately, and its importance as a piece is becoming more clear to me with each spin. Written by the trombonist Juan Tizol, and brought to its current fame by Duke Ellington, the tune may be the one that started two major schools in jazz. First, with its Latin and Mideastern melodies and rhythms, it is very likely the one that made jazz international. Second, with its long sections built on unstable chords (dimished and dominant), it may have been the origin of modal jazz (although the blues were involved as well, of course). And to top it off, it's just a great piece of music. Here's a terrific version: http://www.youtube.com/watch?v=z4XKHkzDggk.

Since its inception, free jazz has been one of the most polarizing styles of music, and it's managed to remain so for over fifty years. Actually, it's an approach to music more than a style, because like certain schools of visual art, the process is meant to be out in the open and noted. It came into being, at least partially, because players were tired of being boxed in by the use of songs and chord changes as improvisational contexts. Theoretically, free jazz is meant to be played without chord changes and to be based on mutual composition in the moment. But what results can often alienate listeners, mostly because there isn't time for any kind of editing.

Ornette Coleman is the first name that comes to mind when the genre is mentioned, and deservedly, because he has dedicated more time to it than any other musician. And because free jazz as a concept is just as divisive among musicians as it is with fans, many of Coleman's peers have said negative things about his music. I think the fact that he's still at it, after over fifty years, speaks for itself. In any event, it's clear that controversy and the induction of thinking are necessary results of what he does, and he know it. As a listener, I find that his best recordings are the ones in which he's in the company of the great Charlie Haden on bass: The Shape of Jazz to Come (1959), Change of the Century (1959), This is Our Music (1960), and Song X (1986), which also features Pat Metheny. Here's the title track: http://www.youtube.com/watch?v=d66Ytt2g7ns

I really enjoy hearing experienced vocalists doing versions of songs by younger artists. This happened a lot in the seventies, when singers, with Frank Sinatra leading the way, began to cover artists such as the Beatles and Stevie Wonder, having realized that some of the best songwriters of that time were the ones working in rock and r&b groups. I think the same thing is happening now to some degree, as serious jazz musicians and singers continue to look to the modern rock repertoire for inspiring material. One of my favourite examples of the phenomenon is the great jazz singer Mark Murphy's version of Coldplay's "What If", from his 2007 masterpiece, Love Is What Stays: http://www.youtube.com/watch?v=EVVSlcMjAJo. It's wonderfully arranged and played, and, of course, sung with his usual combination of head and heart.

The title track from the Bad Plus' most recent release, Never Stop (2010), is a blast. A composition by their bassist Reid Anderson, it was originally written for a fashion show that the band was commissioned to score, and you can hear how its rhythms might have been inspired by imagined parades of models. The tune is straightforward in one way, but it's kind of tricky in another, because the beat gets turned around several times via the use of asymmetrical figures. Of course, this device is one of the secret weapons of Radiohead, a band that the Bad Plus have covered several times during their fascinating career, and it's not impossible that they picked up the idea as a result. But maybe not, because they have done tunes by a few other artists as well. In fact, I wonder if there's ever been a band that have covered such an eclectic list of sources, which includes Black Sabbath, Queen, Yes, The Pixies, Neil Young, Nirvana, Roger Miller, Blondie, Led Zeppelin, Heart, Burt Bacharach and Hal David, Ornette Coleman, Rush, David Bowie, Wilco, Pink Floyd, the Bee Gees, The Flaming Lips, and several others. It's quite amazing, really. Oh, and I didn't even mention the classical composers that they've covered - Stravinksy, Babbitt, Ligeti among them. But perhaps the most astonishing thing about the group is the fact that their most compelling music is found in their original compositions, which are contributed by all three members. We're talking about a great group here. Here's the link: http://www.youtube.com/watch?v=hfSEVk8f2Co

The great pianist Wray Downes (http://www.myspace.com/381846361/music/songs/For-You-3209961) uses the term "deep time" to describe the effect achieved by the very strongest players, rhythmically speaking. A musician who achieves it has a sound that seems to expand with every note played. It allows the listener to hear into the very structure of the instrument, right into the grain of the wood in the case of the guitar and upright bass. Two musicians who provide an excellent example of the phenomenon are Jim Hall and Ron Carter, who have made three albums as a duo: Alone Together (1972), Telephone (1985) and Live at the Village West (1995). The track linked below is one of my very favourite versions of "Autumn Leaves", from Alone Together. It's everything jazz should be, played with deep time: http://www.youtube.com/watch?v=wjfN5NKnJ90

George Shearing, the great pianist, composer and band leader died a little less than two weeks ago, at the age of 91. His story is an amazing one, and this site tells it better than I could, so have a look: (http://www.georgeshearing.net/). Known as a musician's musician, he was a brilliant pianist who made major innovations both vertically and horizontally (i.e. melodically and harmonically). A great writer as well, his most famous piece "Lullaby of Birdland" has become a staple of the jazz repertoire. But my personal favourite is "Conception", a tune I first heard on Bill Evans' debut album, New Jazz Conceptions (1956). It's the sort of tune known as a "minefield" among jazz players because of the extremely challenging nature of its chord changes. And, on top of that, it's usually played at a high tempo, as it is in this version, which features glittering solos from the magnificent guitarist, Chuck Wayne and Shearing, and great ensemble work from the whole group: http://www.youtube.com/watch?v=0KQCtE2t1kM.

Unusual guitar tunings can inspire some great songs. It was certainly the case with The English Beat's "Save it for Later" (http://www.youtube.com/watch?v=0bM0wVjU2-k) which was written as a result of the singer Dave Wakeling's experiments with the concept. Open tuning is a better name for it, actually, and it's been integral to the sound of artists as various as the Rolling Stones, Nick Drake and the Velvet Underground. One reason for it leading to creativity is that it can turn the guitar into a stranger, technically speaking, because the notes on some of the strings have changed places. Therefore the guitarist has almost no choice but to be creative, because all of his or her stock phrases, voicings, licks, and so forth are no longer accessible. (I remember hearing one guitarist say that a big danger for those who play the instrument is that by constantly going back to familiar places, "the guitar can end up playing you".) Another related idea is the fact that some writers compose using an instrument with which they're relatively unfamiliar to avoid the cliches that are the inevitable result of learning music. Perhaps cliches is too strong a term, maybe vocabulary is better, because I don't want to sound like I'm denigrating memorized patterns - serious playing is impossible without them, but for the purpose of writing, they can be, and usually are, counter-productive.

Back to the tune in question. I think it's safe to say that you'd know you'd written a good song when Pete Townshend wants to cover it, which was the case here, but apparently he had to phone Dave Wakeling to get help with the tuning first. (It's D-A-D-A-A-D, by the way.)