People who enjoy classical music often characterize it as "serious." I also enjoy the classical idiom, but can't accept the implication that theirs is the only serious style. Musicians who prefer jazz are as serious as any you'll ever meet. The difference is that for conservatories and symphonies, the central element is the composer -- for jazz, it's the performer. In fact, a jazz musician is a composer, instantly transforming a familiar tune right before our ears.

This takes strong chops and big ears -- and I'm delighted to report that the Hot Mustard Jazz Band has got 'em. For jazz musicians, skill on one's instrument is "chops" -- strong chops means good player. "Ears" is the ability to hear melodies and harmonies -- a guy with big ears can hear once and remember forever. You get chops by practice. "Woodshedding" on your "ax" is not something you should do, it's what you must do if you want to stay in the business.

I practice every day. Even so, strong chops is something I may never achieve. For one thing, I started much too late. The trombone was a present on my 30th birthday. I was assigned to our embassy in Bamako, Mali, and used to joke that the weird noises I made kept the cobras out of the garden. Ten years later, while assigned to our embassy in Algiers, I brushed the cobwebs off the horn and decided maybe it was time to learn how to play it, so I started studying at the conservatory there. I'm still studying. Fortunately for me, the trombone is usually not a solo instrument, and the virtuosos in my band carry me along.

There's no jazz without rhythm. As in life, if there's no pulse, baby, it's dead. But when the rhythm instruments work together and kick up energy and fire, jazz is the world's most exciting and joyful musical style. Dude Brown is a drummer who listens -- he constantly supports and lifts the ensemble. I think of his beat as "fluid drive." Larry Eanet on piano is the essence of swing. To me, he sounds like Teddy Wilson. Marty Erickson provides a solid and propulsive basic bottom. He makes the tuba dance and strut, and he's equally fine on string bass.

I've heard musicians put others down: "He's just a technician." What they mean is that technique is necessary, but not sufficient. For jazz, perfection may be the wrong goal -- if you never hit a wrong note, maybe you're not trying hard enough. You've got to tell a story and make the instrument sing, not just play notes. You don't have to be a musicologist to sense the difference between craft and art.

A sad truth about music is that frustration may be inevitable: The instrument will beat you every time. No matter how much you practice or how hard you work, there will always be things you want to communicate through music that you simply lack the ability to express. And there will always be another player, somewhere, who can do something on his ax better than you can.

But in striving for facility and technique, jazz players try not to lose their personal sound, a way of phrasing that is their own and no one else's. Slam Stewart's bowing and humming, Erroll Garner's lagging left-hand block chords, Vic Dickenson's amazing growls and slurs -- jazz players like these are instantly recognizable.

Jazz improvisation is based mainly on the repertory of American popular song. Those evergreen melodies by Gershwin and Harold Arlen and others provide the themes -- the jazz is in the endless variations. But you've got to know the themes before you can improvise around and off them. You're expected to be able to play any standard, in any key, any style, any tempo, and do it perfectly.

No combo could carry enough sheet music for that, and in any event paper shifts the emphasis from performer to arranger. That's why we avoid arrangements -- except "head" patterns and riffs we work out right on the spot. If you use written music, sooner or later the lights will go out, music stands will fall over, or you can't find your part. It's just easier to work with musicians who have big ears and lots of experience, who know all the tunes ("everything from Bunk to Monk"), and who can spin and weave new melodies right out of their soul.

But those instant improvisations are written on the wind. This is ephemera with a vengeance. You hear a guy blow his heart out, and no matter how lush the sound, how inspired the inventions, they're gone forever -- unless they're recorded. The recorded archive is the legacy of jazz. Malraux's Imaginary Museum becomes for jazz record collectors the Imaginary Concert. Which is why I'm so pleased we've been able to record the Hot Mustard Jazz Band. Guys like Sonny James on trumpet and Country Thomas on clarinet and tenor sax deserve to be heard -- often.

Practice is lonely, but music offers some unusual compensation. There is no other line of work where you get such an immediate reward -- the roar of an enthusiastic audience, the bows, the encores. A recent biography of Louis Armstrong said, "He lived for that applause." Musicians understand that.

People in other countries recognize jazz as America's most significant contribution to world music. I'll concede that Hot Mustard's brand of Dixieland and small-band swing is as much entertainment as art, but we've yet to see any audience fail to respond. There seems to be something about this style of music that just makes people happy. Let others define "serious" music. As long as people are happy hearing our jazz, we're happy playing it.