This article originally appeared in April 1982 in Science 80, the consumer sister of the journal Science. It helped Science 80 win that year's National Magazine Award for General Excellence. Ten years later, I updated the article for Reader's Digest, which published it in more than a dozen languages on six continents.

The Sound of Silence

The strange noise we hear in a quiet room is a medical warning.

By Terry Dunkle

One morning when my office was unusually quiet, I noticed a high-pitched tone, like the rarefied whistle of a TV set warming up, only fainter and higher. I had heard that sound before, in other quiet places, and wondered what it was.

It wasn't the lights. When I switched them off, their monotonous hum fell silent and the whistle seemed even louder.

I stepped into the closet, shut the door, and waited for the tingle and clang of the coat hangers to fade. The whistle was still there. Evidently it was inside my head.

"That's your tinnitus," Jack Vernon told me on the phone. (He pronounced it "tuh-NIGH-tuss.") "Almost everyone hears it at times. Have you had a lot of coffee this morning? Aspirin? Are you taking antibiotics?"


"Then your tinnitus may be naturally loud. Be careful—your chances are about one in five of eventually hearing it all the time. I have a clinic full of people desperate to get rid of it."

Vernon, who runs the University of Oregon's Hearing Research Center in Portland, has treated 4000 victims of severe tinnitus. They come to him from almost every country. He described a typical case: a 42-year-old factory worker wakes up one morning with a noise in his left ear like screeching subway brakes. He tries aspirin, Valium, exercise; the screeching won't stop. Within days, his blood pressure and adrenalin rise to panic levels. He feels like running away, but can't.

At Vernon's clinic the man is fitted with a "masker," worn like a hearing aid, which plays noise into the ear as a distraction. Masking gives partial relief to some, depending on the pitch and loudness of their tinnitus. (Many victims hear pure tones, whose pitch varies with the individual. Others hear complex mixtures that resemble sirens, train whistles or grease sizzling in a pan.) Some patients can be helped by drugs, biofeedback or hypnosis. Still others must learn to live with the noise. A few are driven to suicide.

Those are only the worst cases. Regular doctors and hospitals handle millions more. "Out of an adult population of 40 million Britons," Dr. Ross Coles of the M.R.C. Institute of Hearing Research in Nottingham, England, told me, "more than 2 million have seen a doctor about tinnitus, and nearly 1 million more have been hospitalized with it."

The same figures, more or less, prevail in every industrialized country. Besides the United States and the United Kingdom, hotbeds of tinnitus research include Germany, Sweden and Japan.

Fully 20 percent of the adult population in such countries is occasionally annoyed by tinnitus. Newspaper items about the affliction often draw floods of letters—many from readers who feared their sound was a sign of insanity. A tiny item in London's Sunday Mirror, for example, brought the British Tinnitus Association 2000 letters.

Tinnitus, like fever, can arise from many things: ear infection, anemia, a tumor pressing on the auditory nerve, blood whooshing through arteries near the inner ear, a hair resting against the eardrum. But only one case in 20 can be traced to something specific.

"The rest," said Vernon, "happen because in our noisy modern world the ear is too sensitive for its own good." A child with undamaged ears can detect a buzzing mosquito delivering only a quadrillionth of a watt to the eardrum. Some African tribesmen can hear a whisper across a clearing the size of a football field.

To understand tinnitus, Vernon said, you have to know how the ear works: Vibrations of the eardrum are relayed mechanically to a piston-like bone, smaller than a grain of rice. The bone's size concentrates the force of the vibrations on the inner ear in the same way spike heels concentrate a woman's weight on a floor. The force is applied to the cochlea, an inch-log fluid-filled chamber containing thousands of "hair cells" lined up like teeth on a comb. Each vibration causes a few hairs to bend, which in some mysterious way generates an electrical signal that the brain interprets as a tone. Its pitch depends on the hairs' position along the cochlea.

"The strange paradox," said Vernon, "is that hair cells at exactly the pitch of your tinnitus often turn out to be broken. This should make you deaf to sounds of that pitch. So how can you be hearing a tone that isn't even there?"

One theory is that while the site of injury is in the ear, the real problem lies in the brain. Vernon explained: "We know that hair cells produce electrical static, even when no sound is coming in. Like a sophisticated music amplifier, the brain recognizes this static and cancels it out with an equal but opposite signal. Now, suppose you wreck a few hair cells. No static from that region anymore. But your brain still supplies the canceling signals, and because there's no longer anything there to balance them, you hear them. In other words, your tinnitus may literally be the sound of silence."

That sounded plausible, I said, but I didn't see how I could have damaged my hair cells.

"Hair cells are as thin as cobwebs," said Vernon. "Almost anything can damage them. Drugs, for instance—especially antibiotics. Some of the mycins can give you tinnitus overnight if you take them during a kidney infection; the kidneys can't filter them out fast enough. But the biggest killer is noise."

Hair cells, he explained, wear like blades of grass. "You can walk on them a little and they spring back, but if you trample them too often, they die. Hair cells simply aren't designed for the racket of modern civilization."

By age 40 most of us have lost some hearing in our top two octaves, just off the high end of the piano. The damage zone creeps downward over the years. We don't notice it until we begin having trouble separating voices in a crowd, making out radio lyrics, or understanding voices of children. By then we are prime candidates for severe tinnitus. A little more noise and the faint whistle most of us hear may turn into a piercing, interminable scream.

I asked Vernon what kinds of noise are harmful.

"All kinds. Ask David Lipscomb at the University of Tennessee. He's an expert on noise pollution."

I rang up Lipscomb.

Ever ridden a motorcycle or a power mower?" Lipscomb asked. "That's around 105 decibels—enough to damage some people's hearing in an hour. Rock concerts and stereo headsets can reach 135 decibels—same as a jet engine. Those levels can destroy hair cells in two minutes. Street noise is 90 in some places. It can harm you in an afternoon. In fact, given enough time, any noise over 80 decibels can do it. That's about as loud as a vacuum cleaner."

Lipscomb said I might be able to trace my tinnitus to a single event. "Ever fired a gun?"

"Once or twice."

"That could have done it. A shotgun blast is 156 decibels—100 times as loud as a rock concert. Did your ears ring afterward? That's always a bad sign."

I couldn't remember.

"It might've been something else. A slap on the ear, even a cap pistol going off."

"Caps!" Suddenly I remembered something from my childhood.

I am kneeling on the back porch, raising a hammer over a roll of caps I have set on the concrete. I swing with all my might. The explosion sounds like thunder, only louder—a lot louder. For hours afterward my hearing is muffled and my ears feel warm and full, as though they've been boxed.

"That could've been 165 decibels, easy," said Lipscomb. "Enough to rip off hair cells instantly."

When I caled Vernon back and told him about the caps, he said, "You're lucky you didn't break your eardrums. The blast might've peaked before your guard muscles could react."

He explained that our ears can defend themselves, to some extent, by flexing tiny muscles that yank the piston away from the cochlea and tighten the eardrums. The same muscles are involved when we wince at a flash of lightning—we're preparing for the thunderclap.

However, the muscles can't react in less than 63-thousandths of a second. A gunshot, the backfire of a passing truck or the pow! of a sneakily lit cherry bomb may plink off hair cells before we know what's happening. Guard muscles tire easily, too, becoming useless after one minute. And they never work well on the treble end of the scale, where man-made noise is concentrated.

"Don't rely on your guard muscles," said Vernon. "If you have the chance, plug your ears."

Fingers are still best for this, he said, although most people use them incorrectly. "Don't jam them in. Put them on that little flap of cartilage in front of your earhole and bend it tightly over the hole. That'll knock off 20 decibels. It works well—unless you need your hands for something else. Then you should wear earplugs or a pair of those muffs worn by airport tarmac workers. Hey, can you hold on a second?"

There was a click on the line, then silence. All I could hear was my tinnitus.

"They tell me I have a patient waiting," he said when he came back. "Are you clear on this now? That tone in your head, quite simply, is a warning: Avoid loud noises. Steer clear of jackhammers, sirens—anything painful. Turn your Walkman down a notch. And for God's sake don't play with caps anymore. I have a sneaking suspicion you're still hearing the scar from that explosion."