A broken upright piano, tilted like the sinking Titanic, stands part-buried in a garden at Glasgow’s Counterflows festival. Experimental composer Annea Lockwood swipes a hand across its exposed strings and beams at the metallic clang. “Great piano!” she says, inviting other musicians and the audience to make their own strange noises by scratching and tapping it with garden debris. It’s one of many pianos Lockwood, 86, has buried, burned or drowned since the 1960s, exploring their changing sounds as they are destroyed – though she says “transformed”. A pioneer of field recordings, her work has ranged from “sound maps” of entire rivers to music made with the peace walls demarcating areas of mid-Troubles Belfast. As she revisits two significant works at Counterflows and prepares a new release of 1975’s World Rhythms, she takes me through her radical career from the very start. Annea Lockwood in October 1968. In the background, a burning piano from which Lockwood is making a live recording. Photograph: C Maher/Getty Images In her hotel, she laughs as we watch a 1966 …