Two veteran free-jazz improv musicians from Switzerland, pianist Irene Schweizer and drummer Pierre Favre, are each headliners in their own right. Their concert together at Reduta this week offers a rare chance to see the art of improvisation in an intimate setting.

Often surrounding himself with dozens of cymbals, Favre is among the most respected jazz drummers in Europe. He returns to Prague after headlining the First Annual Free Jazz Festival here last spring, when he appeared in a duo with Chinese lute (pipa) player Yang Ying.

Schweizer is an overlooked pianist from the European free jazz scene. Both she and Favre have paired off with many other musicians over the years, but they share a unique bond as an improv duo that goes back 40 years.

In a recent documentary about her life, titled Irene Schweizer, she says, "Yes, ... Pierre Favre is certainly my oldest music partner." She first met him in the mid-'60s, when he asked her to work as a secretary at a company where he was employed testing cymbals. They began practicing together after work — sometimes both on drums or he on drums and she on piano.

Schweizer's style began to change in the early '60s, when a contingent of exiled jazz musicians from South Africa's apartheid regime, including pianist Dollar Brand (who later changed his name to Abdullah Ibrahim), based themselves in Zurich. Many young Swiss jazz musicians were profoundly influenced by these players.

Caught up in the influence of the free jazz movement, student riots on the streets of Zurich at the end of the '60s and then the Swiss women's emancipation movement, Schweizer became radicalized both politically (as a feminist activist) and musically (as a reborn avant-garde jazz player).

Schweizer and Favre's last recording together, Ulrichsberg, was recorded live at a jazz festival in Ulrichsberg in 2003, and their current concerts are usually just as intense. Favre is a powerful source of energy on drums and percussion; he's neither an experimenter nor a showman. Schweizer, in her distinctive style, meanders around or along with his driving force, which seems more influenced by ethno-African or Japanese drumming or even hard rock, like Led Zeppelin's John Bonham, than bebop or avant-garde jazz.

Asked in the documentary why she prefers drummers as duo partners, Schweizer says, "I play with drummers because I myself am a drummer. I play the piano in a very percussionist way." When she's asked to describe her music, Schweizer responds, "What is music for me? Sound ... that's it. Why should we explain music with words? Music is music."