When Swiss conductor Baldur Brönnimann was a student 25 years ago, "if you had more than 30 people at a concert it was a failure because it was populist crap". Today, there are growing signs that contemporary classical music is shrugging off its elitist reputation, with audiences flocking to work previously regarded as austere and impenetrable.
"It's the weirdest pieces which get the strongest reaction," says Brönnimann. "Prometeo by Nono is an extremely difficult piece to listen to – two hours long with no break, either extremely soft or extremely loud, and with the audience in darkness surrounded by the performers – but it gets an amazing response. People are looking for something to get their teeth into."
Programmers are working hard to meet this appetite for sonic adventure. Last week, the Southbank Centre in London announced a year-long festival which will bring to life The Rest is Noise, Alex Ross's 250,000-selling history of 20th-century classical music, accompanied by a series on BBC4.
Before that starts in 2013, a plethora of "difficult" works will be performed in UK concert halls. From next month, the English National Opera (ENO) is staging four operas written in the past 30 years, including John Adams's The Death of Klinghoffer, about the 1985 hijacking of an ocean liner by the Palestine Liberation Front, conducted by Brönnimann and staged by War Horse director Tom Morris.
In March, there are festivals of minimalist music in Glasgow and north-east England, and a John Cage-inspired "happening" called Musicircus will be staged at the ENO, involving audience members, with musicians including John Paul Jones, formerly of Led Zeppelin.
In April, a festival devoted to Conlon Nancarrow hits the Southbank. Nancarrow, whose fans include Stephen Fry, composed music which is impossible to play except by a mechanical piano. "It makes you laugh out loud," says the centre's head of classical music, Gillian Moore. "You've got two or three completely different time signatures going on. You think there must be a third hand, they must have three brains, and then you realise it's a machine – but it's music of amazing accessibility."
In May, Philip Glass and Robert Wilson's opera Einstein on the Beach – five hours long, with no plot or interval – will make its UK debut at the Barbican in London. Last weekend, the venue offered "total immersion" in the work of British composer Jonathan Harvey, who melds orchestras and electronics.
Moore says the increased audience for these works is the result of a campaign to reach people interested in the cutting edge of other contemporary art forms, rather than those who prefer to hear Beethoven. In 2003, when artistic director of the London Sinfonietta, Moore inaugurated a series of concerts which programmed avant garde classical works alongside music by artists on Warp records. "We were hugely nervous but we wanted to make the connections between Aphex Twin and John Cage, Squarepusher and Stockhausen."
The concerts were a success, and Moore found the people who attended had "an almost unlimited appetite for music of richness and complexity". Better still, they kept coming back. "Immediately afterwards we did a weekend of Xenakis and it sold out. A lot of the people had been at the Warp project, including a lot of the artists themselves. I remember picking the Aphex Twin out of the returns queue for tickets because it was so mobbed, and that was wall to wall Xenakis – no frills."
Brönnimann confirms that many people arrive at the avant garde of contemporary music via the wilder shores of pop. "I did a tour with Joanna Newsom, 15-minute songs arranged by Van Dyke Parks, and the audience who came are the ones who look at contemporary music. They look for something that goes deeper, to undiscovered worlds – the bottom of the sea."
Such audiences have a hunger for the new, says Esa-Pekka Salonen, principal conductor of the Philharmonia. "There's a trend in our culture to be constantly up to date because we're connected through the internet, and an art form that would be entirely backward-looking and museum-like would make no sense. People are interested in what's happening right now."
Some also clearly enjoy the challenge of pitting themselves against some of the most forbidding art works in the world – an attitude encouraged by soprano Barbara Hannigan, whose performance of Boulez's Pli Selon Pli at the Southbank last year had, she says, even musician colleagues in the audience "saying 'I was scared.' But afterwards, they said 'My God, I was touched.' "
Hannigan cites a 2010 Guardian piece by Alex Ross bemoaning that modern classical music is not widely enjoyed in the same way as modern art or architecture. "He said that audiences expect classical music to be 'a spa treatment for tired souls'. I was thinking, maybe the public needs to think of it as a deep tissue massage. It's almost violent – but you know you're going to come out of it feeling a sense of release. If they go in knowing it's going to be intense and heavy, they come out with a feeling of being changed, of accomplishment, of going through something which was quite good for them."
The composer George Benjamin, whose opera Written on the Skin will debut in July, points out that modern classical music relies on individuals to champion it, like Salonen and Vladimir Jurowski, principal conductor of the London Philharmonic. "I came out of Pli Selon Pli very deeply fired up and inspired by it, but it only gets played once or twice a decade in the UK. Even more so than film or visual arts, we have to have not only promoters but performers who are willing to pay the extra expense of rehearsing new pieces and of taking a risk and knowing how to conduct these very difficult works – it's not only the public that are part of this equation."
Cellist and music curator Oliver Coates says that while contemporary classical music has lost the academic air which made it so off-putting, it still requires effort. "I don't think classical music should be put on in bars and clubs – people shouldn't drink or talk over it, they need to be immersed in it. It remains quite serious music."
Moore recommends listening first on Spotify (see her picks below), adding that some awareness of context is required. "That's why The Rest is Noise festival is going to be great, because it shows why certain music was made at certain times, like Stockhausen after the war saying he couldn't write four beats in a bar because it reminded him of jackboots.
"So he exploded everything and created rhythms which were like stars and harmonies – constellations of sounds from the scientific world."
Brönnimann and Salonen agree that the shock of the new has worn off some works, making them more accessible to modern audiences. "So many of these sounds have become more daily for us," says Brönnimann. "Just as contemporary art has filitered into fashion or design, if you listen to film music or video game music, people are getting used to expecting sounds not to be straightforward but to have a life of their own."
Nevertheless, works like Role Player by Christian Lindberg, in which Brönnimann was "shot" by the soloist, then carried offstage while the piece finished without him, are clearly not for everyone. "The great thing about contemporary music is that no one walks out and can't remember what they heard," says Brönnimann. "Some people hate it, some love it, but they all talk about it. That's the response you want from art."
Curious?
Gillian Moore picks five modern classical piece to get you started
Shimmering clouds of orchestral sound, the soundtrack to Kubrick's 2001
Conlon Nancarrow, Player Piano Studies
Superhuman piano music, hilariously impossible, crazy rhythms
Jonathan Harvey Mortuos Plango Vivos Voco
The sounds of a boy's voice and a bell morph into each other through computer magic
Gorgeous, exquisite Japanese modernism tinged with impressionistic harmonies
Louis Andriessen, De Staat
Hardcore Dutch minimalism: brass, voices, electric guitars
Listen on Spotify: http://spoti.fi/Ao9Fbm
• Corrected on 31/1/12 Gillian Moore is no longer head of contemporary culture at the Southbank centre but head of classical music. Einstein on the Beach should also be credited to Philip Glass and Robert Wilson, rather than just Glass. This has been corrected.
