CHARLESTON, W.Va. -- Indian classical music dates back more than 3,500 years. Even if you have no clear notion of what the music sounds like, you probably can conjure images of the sitar, a guitar-like instrument with many more strings and a gourd-shaped body, or the tabla, a pair of drums (one made of clay, the other of wood) that are played with intricate finger strokes.You would not expect to hear a saxophone in such an ensemble.But saxophonist George Brooks has been playing with Indian classical musicians for more than 30 years. You can hear how that unlikely combination works when he joins bamboo flute player Ronu Majumdar and tabla player Ramdas Palsule for a concert at the India Center at 7:30 p.m. Sunday.Brooks is a jazz musician and composer who has collaborated with the avant-garde American composer Terry Riley many times. I talked with Brooks by telephone when he stopped at a coffee shop in Berkeley, Calif., to take a break from driving to a performance.I wanted to know how he approached playing a Western instrument in a non-Western musical group.He said, "You have to be familiar with Indian classical music. I have been studying it for over 30 years now. But, like any improvisation, it requires a lot of listening."Indian classical music is derived from melodic cycles (ragas) and rhythmic cycles (talas). Brooks says understanding them is a requirement to play with other musicians.Ragas are vaguely like Western scales, whether tonal or modal, but he says ragas have a lot more pitch hierarchy than a scale."In a scale, you have the tonic, which is the most important note. But in a raga, certain notes have to be emphasized along the way before you move to other notes that are emphasized."Those emphases must be done in the proper order at the proper time. And when you play in a different raga, things change."Certain melodic movements are required depending on a raga," he said.So as an improvising jazz musician, who would be used to trying anything he wanted to try, well, that wouldn't work. He adjusts to the style of Indian music.Another problem is of source. Western music is based on an intricate interplay of harmony, melody, dynamics, timbre and rhythm that yield texture and form. You can write these things down on paper, hand them to another musician and they will understand what you want.Brooks says Indian classical music is more of a language-based art. So, you literally learn how to play by speaking the sounds that you are going to play on your instrument. (If you have ever listened to a couple of percussionists singing rhythms back and forth, you have a simple notion of the idea of language-based music)."Working with high-level Indian musicians requires an immersion in that language," he said.When asked about rhythm, he said, "In rhythm, talas, the idea is cycles -- moving towards one in the cycle. Say in a seven-beat cycle, everything is moving toward one. There is a lot of rhythmic interplay among the instrumentalists."The thing that sounds so different about Indian classical music to Western ears is its harmony. Or the apparent lack of it.Indian classical music doesn't have the functional or coloristic biases of Western music. You don't have a bass that grounds the music in a key, then forces it in new directions through modulation to a new one. Nor do you have the colorful, non-functional harmonic shifts of modernism (think Debussy).Brooks says harmony is there nonetheless. "Harmony is implied or described over a series of tones. They might not resolve them in the way we are used to. With the popular music of Bollywood, [Western] harmony might be creeping in more. Things just don't resolve as fast as we expect them to."I wanted to know how the form of a piece might work."There is a flow to a piece," he said. "We start with the exposition of melody, then exposition of rhythm, then of rhythm and melody together. There are a lot of targets one is going for.""Pieces in Indian classical music can be long -- an hour and fifteen minutes. For this concert, in the first half we play a longer piece, and then some shorter works in the second half."(If you listen to American popular music, that is long. There are plenty of pieces in concert music at that length, though, like Mahler's Fifth Symphony, for instance.)Finally, Brooks said that the music isn't always about him fitting into the Indian traditions. His experience as a jazz musician rubs off on the others. "I like to keep it fresh on stage. I like a little monkey wrench in the works now and then. My approach isn't as strict, so it loosens them up a bit."