Ten years ago, a weekend devoted to Helmut Lachenmann’s music at the Southbank would have been unthinkable. Lachenmann was deemed a bovver-boy composer – one of the awkward-squad whose music had a tendency to pose unpalatable questions that the classical mainstream wished would go away; a composer best left to the Huddersfield Contemporary Music Festival, or to an already devoted New Music audience at one of London’s smaller venues.

So what’s changed? Certainly the Southbank has done nothing to sweeten the Lachenmann pill. The opening concert (Saturday October 23rd) features Lachenmann’s breakthrough quartet Gran Torso (1972) and the more recent Grido (2001) played by the Arditti Quartet; then, after an onstage interview, there’s a selection of chamber pieces performed by Clio Gould, Sarah Leonard, Olivier Coates, Rolf Hind and Lachenmann himself. On Sunday October 24: Lachenmann’s omnivorous orchestral Schreiben (2003) and Ausklang (1984-85) for piano and orchestra, played by Hind and the London Sinfonietta under Brad Lubman.

In one sense nothing much has changed. Lachenmann’s upending of lazy expressive affectation, and determination to make audiences think "whither music" by querying the borders of music and noise has remained his constant preoccupation. String players no longer bow and pizzicato, plain and simple – Lachenmann requires them to play along a spectrum of sounds, some pitched, others not, with different parts of the bow and fingers, and with plectrums. Continuing this relentless quest for primary sound-sources, brass and woodwind players blow on, against and into reeds and mouthpieces while Lachenmann’s rethought musical notation instructs them when to rattle and shake instrument keys and valves.

And why? Because he believes that bringing music spluttering back to life involves reverse-engineering conventional technique, breaking down musical protocol, cutting the umbilical chord as a way of giving birth to new sounds, of each piece feeding off the past as a newborn autonomous being – because, as Lachenmann points out, the most traditional thing about tradition is its radicalism.

But the world has changed around Lachenmann. In June, the London Symphony Orchestra performed an orchestral redux of Grido, alongside a performance of Brahms’ First Piano Concerto played by his friend Maurizio Pollini, and Lachenmann has reached an age – 75 in November – where he’s talked up as "Germany’s senior composer". Any recording you want, including two of his mid-90s opera Das Mädchen mit den Schwefelhölzern, is but a click away.

And the Southbank has been commendably conscientious in building an audience for music that uses the apparatus of "classical music", while issuing probing questions about its practises; this Lachenmann weekend follows recent festivals built around Karlheinz Stockhausen, Edgard Varèse and Luigi Nono, music that hooks in audiences from the parallel universes of experimental rock, electronics and improvisation. But will Lachemann appeal to the same audience who come to MacMillan and Turnage? My honest view is that there’s only minimal overlap. After all, you’d never catch one of them threatening to bring the whole house tumbling down by asking: “My music might not be music, but what is it? That’s the crucial question: what is music today?”

Philip Clark

For more information, visit the South Bank's website