Review / Escaping from behind bars: Nick Kimberley on improvisation from Shiva Nova

ARE there intrinsic differences between what is improvised and what is notated? The ensemble Shiva Nova has consistently attempted to extend contemporary composition by bringing together performers from European and Asian traditions. Looking further afield, Shiva Nova's latest series of London concerts has embraced African music and jazz. In the Purcell Room, the final concert of the series began with two short marimba improvisations by Orphy Robinson, the London jazzman.

With a sound that unites Indonesia, Africa and Latin America, the marimba already achieves a kind of fusion. Robinson inflects it with yet another musical language, that of jazz. Using both ends of his mallets, and striking parts of the instrument not usually considered musical, Robinson built up a dense and fiercely rhythmic wall of resonating sound. He was then joined by the sitar player Dharambir Singh and the tabla player Sarwar Sabri. While tabla and marimba fed rhythms to each other, the sitar rode around and across them. Joe Harriott and John Coltrane were suggesting possibilities for Indo- jazz fusion in the 1960s, long before 'fusion' became a dirty word. What we heard here extended those possibilities, with the sitar picking a careful way between the two musics.

Intentionally or not, there was the feeling that all this was a curtain-raiser for the premiere of Priti Paintal's Polygamy, for sextet divided into two 'teams' - improvising marimba, tabla and sitar; flute and piano playing from notation; and the cello as moderator, moving between improvisation and notation. In true jazz style, Polygamy began with a rudimentary theme from which the piece could grow. As Helen Crayford pounded out the piano chords, it seemed as though Paintal's theme might be mere parody. Then the improvisers picked up the baton, the rhythm loosened, and the playing developed a suppleness that the work's opening had not promised. What was most startling was the way in which each instrument's sound-world inflected the instruments around it, so that it was possible momentarily to lose track of the source of individual sounds - a virtue, not a fault. Crayford's playing took on the joyous assertiveness of the great stride pianists, the timorous flute - ably played by Nancy Ruffer - came into its own, while the cellist Neil Heyde studiously ensured that everyone knew where the piece was going.

In a performing process such as this, composer and musicians must trust each other if the music is not to become tentative or perfunctory. Polygamy worked because that trust had been firmly established, proving that improvisation can be one of the composer's most potent weapons.