As a professional dance critic, and a self-confessed ballet nut, I have spent my life in thrall to Tchaikovsky. I love the sound of a big orchestra in a big lyric theatre blasting out one of his big ballet scores. The louder the better, and The Sleeping Beauty best of all. So when I had the chance to sit in the orchestra pit during a performance of Sleeping Beauty at the Royal Opera House it was a fantasy come true. How better to experience the lustrous wonder of that majestic music than to sit beside the musicians who play it?

I knew the sound was going to be fantastic, and it was – Valeriy Ovsyanikov and 75 musicians of the ROH Orchestra saw to that – and it was indeed thrilling to be down there in the middle of it. But as the Rose Adagio unfolded, and Tchaikovsky’s writing grew ever grander, another sensation began to worm its way into my consciousness – pain. My ears started to hurt, thanks to the short sharp shrieks of the flutes, the crash of the cymbals and the blare of the French horns.

Imagine, therefore, how you would feel if you were a professional musician and you were playing Sleeping Beauty every night, or indeed Strauss’s Salome or any part of Wagner’s Ring cycle? A wall of sound may be exciting for audiences, but it can also mean exposure to damaging levels of noise for musicians trapped in a pit like goldfish in a bowl.

Which is why, just to my left on Saturday night, a microphone and a nifty little digital meter were busy recording the impact of Tchaikovsky in the pit. This is now standard procedure at the Opera House, where every ballet and opera carries a meter reading so that management can assess how much noise musicians are exposed to every week. Sleeping Beauty, it transpires, is rated at 87 decibels. The allowable daily limit is 85, averaged out over the course of a week.

Along with other opera and ballet companies in the UK, Covent Garden is preparing itself for amendments to EU legislation relating to noise in the workplace. For most industries the regulations came into effect two years ago, but music and entertainment were granted an extra two years to find ways to adapt to the limits. That extension expires on Sunday, and orchestral managers have been thrown into a tailspin. They are spending tens of thousands of pounds consulting acoustic engineers and compiling complex databases, installing noise-reducing screens and buying earplugs for their players. They are metering their shows and rearranging their performance schedules accordingly, so that noisier productions are shared with quieter ones during the working week. And all without leaving audiences feeling that their musical night out has been compromised as a result.

The regulations are designed to protect factory workers and other employees forced to carry out their jobs against a backdrop of loudly humming machinery. The irony is that for orchestras noise is their business, which makes it doubly tricky for them to function within the EU directive, especially when a Swan Lake clocks in at 90 decibels.

“Industry is trying to block out the hazard of noise altogether,” says Chris Clark, orchestra operations manager at the ROH and a musician himself. “But the hazard is what we are here to produce. Still, some of the noise in the pit can be somewhere between a pneumatic drill and a jet plane taking off. We are dealing with very real noise levels; these regulations are not a joke.”

After years of campaigning to protect its members’ hearing, the Musicians’ Union has welcomed the revised guidelines and has even come up with “hearing passports” to help freelance members to calculate their daily or weekly noise exposure. “Let’s be realistic,” says Pauline Dalby, the union’s safety and learning officer. “Most musicians will have to resort to wearing earplugs at some time during their playing, but there are lots of other combinations of noise control.” Which is just as well since, unlike rock stars who routinely use them, many orchestral musicians are reluctant to wear earplugs because they dull the nuances of their sound.

Rock and pop artists have been well aware of the threat to their hearing for years. Stars such as Sting and Pete Townshend have spoken openly about their hearing loss, and it’s not uncommon to see acoustic baffles separating band members at arena gigs. Classical musicians, though, have been slower to wake up to the threat. Those most at risk are the ones whose careers are spent in the orchestra pit, where more than 100 players can be crammed into a confined space with sound reverberating around them in a kind of sonic trench. It’s why employers such as the ROH are taking the legislation so seriously, even if it means a mountain of administrative paperwork to monitor each player’s average weekly decibel exposure.

Covent Garden is well aware that some musicians have harmed their hearing through playing for ballet and opera. William Morton, who retired in 2000 after 40 years in the ROH Orchestra, is a case in point. He suffered so much hearing loss during his career that he had to wear a hearing aid. He played the flute and the piccolo; the latter, surprisingly, is potentially one of the most damaging instruments.

“I lost quite a bit of high-frequency hearing, although it was hard to prove that it was entirely due to working conditions in the pit,” Morton says. “But looking back I realise I knew quite a lot of musicians who suffered from hearing loss. And I saw quite a few who were playing out of tune and getting lost in their own little world because they couldn’t hear properly. I tell my students to go easy when playing high notes. It’s very easy to get carried away, but it’s dangerous. The damaged hair cells in your inner ear do not regenerate.”

Is Morton in favour of the new regulations? “I’m very much in favour of anything that reduces damage to hearing. But we should also ask ourselves: does the music have to be as loud as it is? Perhaps it’s time to blow the whistle – gently – and say this has got out of hand. Perhaps the best method of noise reduction is to play more softly.”

Which isn’t as easy as it sounds. Put simply, live classical music is more fortissimo than it used to be, and I’m not talking about the kind of electronic amplification that West End musicals and rock gigs rely upon. “There is no question that orchestras have got louder in the past century,” says the conductor Barry Wordsworth, music director of the Royal Ballet. “The amount of sound Henry Wood would have been expected to produce in 1900 is nothing compared with today. Cymbals are twice as big now, flutes are metal instead of wooden, violin strings are metal too instead of gut, all brass instruments are bigger bore, which means that they need more puff and they produce more noise.”

We the audience are also to blame. Thanks to our iPods and surround-sound speakers we have come to equate volume with musical virtue, and conductors are not immune to our preferences. “There are conductors who are guilty of encouraging people to play too loudly because they think it’s more exciting,” Wordsworth says. “And orchestras generally play louder than they need to. But louder doesn’t necessarily mean more beautiful. Conductors need to learn that if the whole level of sound comes down, but the contrast between piano and fortissimo is as big as it can be, then it will still be as exciting for the audience.”

Composers, too, are having to come on board. “Harrison Birtwistle told me that he was very, very aware of the noise at work regulations,” Hazel Province, orchestra director at the Opera House, says. “And that he had been aware of them while he was writing The Minotaur.” Birtwistle’s new opera opens at Covent Garden on April 15, shortly after the new regulations come into effect.

At the Royal Opera House, Chris Clark is the person charged with implementing the antinoise measures. “What we’ve understood from the enforcement agencies is that we do not need to be operating at all times under the weekly average,” Clark says. “But at all times we do need to do everything we can to lower a musician’s exposure to noise when we go over it. We have a whole range of solutions. We have changed the orchestra’s layout to spread out the noise; we rotate players so that someone is not always sitting at the back; sometimes seats are taken out at the extreme sides of the auditorium to let the sound escape from the pit. We have large acoustic baffles between the wind and percussion. We are able to do a lot with screens that absorb sound and reflect it into the audience.”

Is the audience going to feel shortchanged? Clark claims not. “It may be softer at the ear of the musicians but it’s actually louder in the auditorium because we are getting the sound out.”

Controlling noise levels is a complex and costly business. “Over the past couple of years we have spent well over £50,000 on noise reduction at Covent Garden,” Province says. “Treating the pit acoustically cost just over £30,000. Personally moulded earplugs cost £200 a pop and there are more than 100 musicians in this orchestra. For some of the smaller chamber orchestras such expenditure is not an option.”

At Welsh National Opera, it’s much the same story. “I wouldn’t be surprised if we spent between £30,000 and £40,000 on research and implementation,” says Peter Harrap, WNO chorus and orchestra director. “But last season we did an enormously loud piece, James MacMillan’s The Sacrifice, and we had loads of screens as it was a very big orchestra. We have to be aware that if a piece like that is in the programme in the future we have to be careful for the rest of the week.”

Birmingham Royal Ballet, which is spending up to £100,000 on noise reduction, is also reconsidering its programming. “The legislation is making us think about how many matinees we do in a week,” says John Beadle, orchestra director for the Royal Ballet Sinfonia, BRB’s orchestra. “If we’re doing certain loud pieces such as Romeo and Juliet or Sleeping Beauty for half the week, then we’ll be looking at doing another work that’s not so loud for the other half.”

For Craig Hassall, managing director of English National Ballet, “ballet without a full orchestra is unimaginable”, but he admits that the company still hasn’t quite worked out what the regulations will mean. “Health and safety has to be the priority, of course,” Hassall says. “But at the same time look at ballet: if it hadn’t existed until now and someone came along and said: ‘Here’s a new dance form. I want the girls to wear these shoes and dance on their tiptoes’, I’d be surprised if it would get through on safety grounds.

“With symphony orchestras it’s very similar. If you didn’t have one, and someone said: ‘I want everyone to play these loud instruments really close together in a pit’, I think people would say you were crazy.”

Like it or not, though, ballet and opera companies are determined to play by the rules. “Unless we treat this legislation seriously the impact on the profession is mind-blowingly scary,” Wordsworth says. “We could all be out of a job if it’s not handled properly because orchestras will be illegal places to work.”

Additional reporting by Louise Cohen

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