The scene was familiar, yet somehow diconcertingly different, as in a dream. I was sitting in my usual seat in my favourite concert venue - the Wigmore Hall in London - listening to fine musicians playing pieces I'd heard dozens of times. All should have been pleasurable, calming and reassuring. It was anything but.

A horrible high-pitched whistling filled my ears, souring the glowing harmonies of Brahms with jangly overtones and obscuring the sinuous beauty of Bach's melodic lines. Some chords, painfully distorted, leapt out like ogres from behind creaky doors. Others were so muffled that they disappeared. I had no sense of the Wigmore's glorious acoustics, only of disembodied sounds. It was like listening to the drifting signal of some Algerian radio station through the crackling static of an old wireless. Only much more distressing.

For any musician or music critic, the prospect of not hearing properly - indeed, of finding that listening to music is agonising - is an ultimate nightmare. It must be on a par with the footballer's fear of breaking a leg. Coping with daily life becomes hard enough. But on top of that is the double-trauma of having your living snatched away and your prime joy destroyed.

On Monday I was given an insight into that dark, desolate half-life. I had been saddened - as many readers must have been - by the story in The Times last week about the large numbers of British soldiers returning from Iraq with permanently damaged hearing, caused by the colossal thunder of warfare. I had also been struck by the degree of deafness now apparent among civilians in comparatively early middle-age.

The ear has always been a delicate, easily damaged and all too temporal organ. As Professor David McAlpine, the head of the UCL Ear Institute, told me: “It was never designed to last as long as we now live.” But the din of modern life has greatly increased the risks to our hearing. It's not just the constant roar of traffic or of machinery in many workplaces. It's also the racket we voluntarily inflict on ourselves.

Kids in ear-splitting dance clubs or gigs think that the temporary deafness they experience the following day won't have any lasting effect. Tragically, that isn't true. And just as damaging is the earphones culture that entices millions to spend hours each day pumping high-decibel music straight into their lug'oles. Experts say that two out of three youngsters - two out of three! - will have hearing problems as a result.

Already nearly nine million people in Britain suffer from significantly impaired hearing. Deafness comes in many forms. But one of the most upsetting is tinnitus, the phenomenon of “hearing” unexplained noises - whistling, whining, ringing, whatever - that somehow emanate from inside the body, not outside. This was the condition that afflicted Van Gogh, Hitler and Michelangelo, and today affects five million people in Britain. That's a huge number, and the effect on their lives can be devastating. The incessant sound inside their heads can stop them from concentrating, having normal conversations, doing their jobs well, or sleeping. It means that they may never enjoy silence for the rest of their lives (for there is no cure, only palliatives). And it can ruin musical enjoyment - which only increases one's respect for performers such as Eric Clapton, Barbra Streisand and Moby who have battled through it.

Some of this I experienced, for three disorientating hours, on Monday. All this year the Royal Philharmonic Society is running a project called “Hear Here!” (www.hearhere.org.uk is its fascinating website) intended to remind us of the vital role that listening plays in our increasingly visual-obsessed world. One of the starkest ways of reminding anybody about anything is to deprive them of it - and that is what I agreed to have done to me.

At the UCL Ear Institute a researcher called Bradford Backus rigged up a gadget - a transmitter with earphones inside ear-mufflers - that simulates tinnitus and loss of high-pitched frequency hearing. This I wore while walking round London, and then at the Wigmore concert. I wish everyone with good hearing could have the same experience. We would all take more care of our ears, and show a lot more sympathy for those who seem distracted or slow on the uptake (but are too proud to say why).

London sounded as if it was under water. As I discovered dramatically, when I almost stepped in front of a bus, traffic noises were reduced to a gurgle - and one, moreover, that was hard to pinpoint directionally. And without high frequencies, sibilants tended to disappear from people's speech. As Professor McAlpine had warned me: “You might find it difficult to tell if women are telling you that you're s**t or fit.”

But the worst aspect was the feeling of isolation. Because the loudest sounds hitting my brain seemed to be inside my body, I felt a surreal sense that the outside world was exactly that: something alien that I couldn't access or communicate with. As Helen Keller said, blindness separates people from things, but deafness separates people from people. No wonder that tinnitus sufferers sometimes feel so lonely.

And then there was the music. The Czech composer Smetana once wrote a string quartet to evoke the shattering effect of his tinnitus. In the last movement, whatever the harmony, the first violin keeps playing a high, piercing E. It's a heartbreaking work. But at least Smetana (like Beethoven) had the genius to turn his agony into a masterpiece. For the vast majority of people with impaired hearing, there is no such consolation, no sense of a “blessing in disguise”.

Halfway through the Brahms on Monday I could stand the whistling no longer. I ripped Dr Backus's gadget from my ears, and experienced pure bliss. The harmonies were pure once more, the instrumental timbres wonderfully untainted. But for millions of people, some far too young, there is no respite. The loss of hearing on such a mass scale is one of the unspoken - or perhaps unheard - tragedies of our time.

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