The UCL Ear Institute stands on Gray's Inn Road, one of the busiest thoroughfares in London. Outside, the din of modern life is relentless - revving motorcycles, idling lorries, honking taxis and the blaring of sirens. Inside, however, director Professor David McAlpine has just led me into what is possibly the quietest spot in our throbbing capital. We are in his anechoic chamber, a windowless room four metres square that could double as a set for Doctor Who. Angular wedges of thick grey foam jut from the walls and ceiling. As I step inside, my feet wobble precariously upon a suspended trampoline mesh because the same foam wedges, it turns out, are affixed to the floor beneath us. Their purpose: to absorb all sound waves. The chamber is, in effect, “dead space”. As the triple soundproofed door closes behind us, my head feels instantly muffled. When the lights are turned off, plunging us into pitch darkness, things get distinctly eerie. “In here,” McAlpine jokes, “no one can hear you scream.”

What I can hear, I realise after a couple of minutes, is that rare thing... nothing. Pure, unadulterated silence. What McAlpine hears, however, is a high-pitched tone, slightly more pronounced in his left ear than his right. That's because while I'm blessed with robust hearing, McAlpine is among Britain's five million tinnitus sufferers.

Often caused by prolonged or sudden exposure to loud noises, tinnitus is most commonly described as “ringing” in the ears. Symptoms can vary widely - from a low hum to a pinging and hissing that drives the sufferer to distraction. For 300,000 people with the condition, symptoms cause sleep deprivation and extreme anxiety, preventing them from leading a normal life.

The fear among auditory experts is that we are heading for a “tinnitus timebomb”. If you regularly spend several hours a week clubbing or going to gigs, or if you listen to your MP3 player at full volume, you will have almost certainly experienced some temporary tinnitus already. Prolonged exposure to excessive decibels can put your hearing in danger of permanent damage. And countless studies worldwide have now confirmed that an overload of noise levels is resulting in increased hearing loss among young people. According to some estimates, noise levels have increased tenfold in recent years - in shops and restaurants, in schools and at work, on trains and planes, on urban streets and in the countryside, the global hum is becoming a global howl.

Of course, tinnitus is not a modern phenomenon. McAlpine reminds me that Thomas Hardy's Jude the Obscure was often troubled by the “sound of fish frying” in his ears. However it has, until very recently, been a clinical enigma with various “trial and error” treatments on offer, but no cure. Advances in brain scanning over the past five years, combined with major pharmaceutical investment, are changing that. According to Vivienne Michael, chief executive of Deafness Research UK: “There is finally hope that tinnitus will not be a Cinderella area of medicine for much longer.”

McAlpine, an auditory neuroscientist and adviser to Deafness Research UK, is regarded as one of the world leaders in tinnitus research. He uses the anechoic chamber to provide rigorous test conditions for hearing and to support his studies into the brain-processing mechanisms underlying tinnitus.

For years, the big question that perplexed scientists was whether tinnitus was a ringing in the ears, or in the brain. “Our thinking now is that it emerges as you go from the ear to the central nervous system,” says McAlpine. “If you have some hearing loss with the ear, the brain tries to compensate by switching up its own amplifier. One theory is that when your brain turns up the dial, it doesn't just turn up the signal for frequency channels, it turns up the noise - so like with a shortwave radio, you hear more sound, but you hear more hiss as well.”

McAlpine is the first to admit that his personal experience gives an added impetus to his work. Now 40, he pinpoints his own condition to a single night, spent in a noisy Irish bar in Sheffield ten years ago, at a friend's engagement party. “It was low-ceilinged room with massively loud music - so loud I couldn't hear myself speak. I was there two or three hours, and remember cutting the evening short because of the noise. As I left, my ears were ringing.” He recovered, but two weeks later, while carrying out audio tests in a laboratory, he realised that he was having problems hearing higher frequencies. Since then, he has had recurring bouts of “mildly annoying” tinnitus, which worsens when he has to do any long-haul travel because of aircraft noise and air pressure. He no longer frequents loud bars, “and I don't know anyone in the auditory world who uses an iPod, except in a very limited way.”

Personal music players must, by law, be manufactured with a maximum volume of 100 decibels (although worryingly, according to Vivienne Michael there are adverts on the internet offering “unlocking” services so that they can be played at higher levels). Prolonged exposure to anything over 80 dBA (the decibel scale) will damage hearing. At clubs and rock concerts, noise levels can reach well over 110 dBA. Even classical concerts can exceed 100 dBA. (If you think the differences seem slight, you need first to remember that decibels are measured on a logarithmic scale, so a small increment can result in a large increase in perceived volume. For those who are not mathematically minded, an increase or decrease of three dBA represents a doubling or halve of intensity - the energy it contains. So, for example, 73 dBA is twice as intense as 70 dBA.)

“If you go to a club, you wouldn't allow someone to shine dangerous lasers in your eyes. And yet people regularly expose their hearing to damaging noise levels,” says McAlpline. “For many young and otherwise healthy people, tinnitus will be the first sign that they are not, after all, invincible.”

Dr David Baguley, Head of Audiology at Addenbrooke's Hospital, Cambridge, and adviser to the British Tinnitus Association, fears it is “imminently likely” that the number of tinnitus sufferers will rise as MP3 use increases. On the upside, however, he points to several breakthroughs that are bringing us closer to discovering the cause of the condition.

In the past five years, researchers in America and also at the University of Nottingham have, with the help of functional magnetic resonance imaging, detected brain activity related to tinnitus. They've found it in the auditory cortex and also the limbic system - the part of the brain that governs anxiety and emotion. “This is hugely significant,” says Baguley. “The suggestion is not that tinnitus is stress-induced, but that stress could be a factor because in people who complain of the condition, the part of the brain that produces fearful emotions is exceptionally active.”

Elsewhere, in Belgium and Germany, studies into repetitive magnetic transcranial stimulation have shown promise for some sufferers. The treatment involves holding a magnetic plate just above the ear where the auditory cortex is. Electromagnetic pulses then alleviate symptoms by disrupting, and possibly resetting faulty brain signals. Sessions last between five and 30 minutes. The treatment is painless and does not require anaesthesia. The downside is that it is highly specialised, and requires the use of expensive equipment found only in major neurology centres.

Among the most potentially exciting developments, according to Baguley, are those within the pharmaceutical industry. Within the past two years, it has been established that injecting the anaesthetic lidocaine into the bloodstream of someone with tinnitus will bring about a complete absence of symptoms for five minutes. “It is actually a very dangerous thing to do, because it has heart and breathing implications, but what it tells us is that somewhere in the brain there is a lock that can be unpicked,” he explains. At least three major pharmaceutical companies are now actively researching a drug solution to tinnitus. “This is a huge step forward in solving the last great mystery of the auditory system,” says Baguley. “Many goals are now in sight in terms of deafness and balance but for too long, tinnitus has remained a heart-sinker of a condition. I'm more and more convinced now that a drug solution will be possible within our lifetime.”

Case study: The ringing never stops

Tom Wilkinson, 29, works in IT development and lives in Topsham, Devon. His tinnitus was triggered by going to rock concerts while he was at university in Birmingham.

“I would always have a buzzing in my ears for a day or two after seeing a band. Then one day, the ringing didn't go away. I got used to it, but tinnitus is exacerbated by anxiety, and during a stressful period a couple of years after I graduated, I sought help. A sound generator under my pillow helped me at nights, and I have invested in specialist earplugs, which I wear if I go to the cinema or a gig now. Tinnitus is a unacknowledged danger among young people because ear problems are associated with middle and old age. I think it is vital that we increase awareness of the dangers.”

How to treat it

Three years ago, a study by the charity Deafness Research UK showed that millions of tinnitus patients were being badly let down by the NHS. The research found that many GPs were unsympathetic and unwilling to refer sufferers to a specialist. More than 50 per cent of patients were being told: “There is no cure. You'll have to live with it.”

Since then the Department of Heath has produced a “tinnitus patient pathway”. Dr David Baguley, a member of the DoH committee, says: “The aim is that all patients receive timely attention and the same standard of care.”

For those seeking treatment, options include:

Sound generators. Tinnitus can be more of a problem during quiet times, such as before sleep, when there are no everyday sounds to mask symptoms. Sound generators are available on the NHS. There are under-the-pillow machines and also a behind-the-ear version.

Digital hearing aids. Conventional aids can aggravate tinnitus symptoms because they block the ear with an ear mould. With a new design, the canal is left open as the hearing aid is connected into the ear by a thin tube.

Cognitive behavioural therapy has been found to improve patients' quality of life, even when the volume of noise from the tinnitus remains the same. It works by helping to change people's attitudes and behaviour.

Tinnitus Retraining Therapy is a specific form of counselling combined with sound therapy.

Some sound advice

A survey in 2006 showed that more than a third of all 16 to 34-year-olds admitted listening to their MP3 player for more than an hour a day and 14 per cent listened for more than 28 hours as week. The Deafness Research UK/Specsavers survey also showed that 54 per cent of people did not realise that listening to loud music on an MP3 player in a nightclub or at a concert could damage their hearing.

The World Health Organisation recommends the 60/60 rule: that you listen to your personal music player for no longer than 60 minutes at a time and at no more than 60 per cent of its volume.

Apple has produced an update that allows people to set the maximum volume on their iPods. It also comes with a code, so parents can stop their children from undoing it. For more information on the patch and installation help visit:

http://docs.info.apple.com/ article.html?artnum=303414

Cinemas and clubs regularly reach volumes of more than 100 dBA. For every two hours of exposure at such levels, your ears need 16 hours of rest to avoid permanent damage.

As a rule of thumb, if you can't make yourself heard easily to someone standing a metre away, the noise level is too high.

Dehydration exacerbates inner ear function. Make sure you drink plenty of fluids if you are in a noisy environment.

Cheap, effective earplugs are unobstructive and can protect the ear from higher volumes in clubs or at concerts without blocking out the sound of music or conversation.

On a plane, noise cancellation headphones will enable you to enjoy listening to music without raising the volume unnecessarily.

Sounds above 80 dBA can damage your hearing:

Nightclub: 80-110 dBA

Pneumatic drill: 110 dBA

Rock concert: 110-120 dBA

Plane taking off 100 metres away: 130 dBA

140 dBA is the threshold of pain for many people

Source: www.dontlosethemusic.com

Deafness Research UK has information and factsheets on tinnitus at www.deafnessresearch.org.uk

British Tinnitus Association has helpline on 0800 0180527 or visit BTA at www.tinnitus.org.uk

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