It was 1969, and in a suburban Chicago basement, the Sounds in Motion were practicing. I was on electric piano, my brother lead guitar. And our father, as usual, was hovering at the top of the stairs, shouting, "Turn that racket down, or we'll all go deaf!"

Twenty years later, I wish I'd listened.

I don't know when I first began to notice myself straining to make out conversations. Everyone, it seemed, was mumbling. Wherever I went -- bustling restaurants or crowded parties -- the background noise would drown out what my companions were saying.

And I was aware of something else, especially when the world was very quiet: a high-pitched buzzing in my ears, a steady whoosh of white noise.

But it wasn't until Pete Townshend and The Who returned last summer for one last tour that I began to worry. Townshend! The Duke of Decibels! He'd made loudness legendary, ending concerts by smashing his guitar in an ear-shattering explosion of amplified noise. Looking a little long in the tooth 20 years after his appearance at Woodstock, he was also -- yes, Dad -- a little hard of hearing.

At a press conference kicking off the tour, Townshend admitted his sacrifice to the years of rock and roll. "You wake up with a piece of your ears gone," he said. "I think it's worth saying that there is a price to pay for that: It's premature deafness and ringing and slotty hearing."

The guitar star's confession made me wonder about the toll of rock-and-roll in my own case. The high-pitched whistling in my ears -- was that what Townshend meant by ringing and "slotty" hearing? Varieties of Hearing Loss

In a soundproof booth at the University of California at San Francisco Medical Center, audiologist Toni Will slipped headphones over my ears and handed me a switch on the end of a long cord. Every time I heard a tone, she told me, I should push the button.

With Will hidden from view at a control panel outside the booth, the tones began -- some high-pitched, others so low I felt more than heard them. It was easy at first. Then I began to strain. Was that a tone? Or that? I could not tell. Finally, Will's voice came over the headphones. "Here's something you probably don't want to hear," she said.

The test indicated that, at age 39, I had a distinct hearing loss.

The bad news was charted on a form called an audiogram. The sequence of tones had been used to measure my hearing thresholds -- the softest sounds I could hear at various pitches. If my ears had been perfect, the audiogram would have shown a flat or somewhat wavy line. Mine looked more like a cross-section of the Grand Canyon -- flat on the left (the low-pitched sounds), flat on the far right (the highest pitches), with a deep V in the middle where my hearing dropped off. It was a classic "noise notch," a textbook example of noise-induced ear damage.

There are two main kinds of hearing loss, Will explained. One, called conductive loss (often caused by ear infections), tends to diminish reception of low-pitched sounds. If you've ever had your ears plugged with water, you know the sensation of conductive loss. The more common form, particularly in adults, is called sensorineural loss. Sensory cells in the inner ear, designed to convert sound waves to nerve signals, are damaged or destroyed.

"Ouch," I said. "And noise is enough to do that?"

"Probably not all at once," Will said. "Usually, the damage takes place over years of exposure to noise."

But if the exposure is haphazard -- at many volumes and many pitches -- its impact can be strangely specific, as my own test revealed. A healthy human ear responds to a wide range of frequencies, measured in units called hertz.

For reasons no one really understands, the damage first begins to show as a diminished sensitivity to frequencies of around 4,000 hertz -- roughly the pitch of the highest notes of a piano.

"Fortunately, most speech sounds are lower in frequency, around 2,000 hertz," Will reassured me. "So you probably don't have any trouble hearing when we're talking like this. But consonant sounds tend to be higher in frequency than vowel sounds. Sounds like 'th' and 'sh' and 't' become hard to distinguish. Children's and women's voices also may be harder to understand because of their higher pitch -- especially against background noise. People often say they can hear well enough, they just can't understand what people are saying."

And noise zaps hearing in other ways. While quiet sounds become too soft to hear, loud sounds may become irritatingly harsh. "Speak in a quiet voice," said Will, "and someone with sensorineural hearing loss will have trouble hearing. Raise your voice, and they're likely to say, 'You don't need to shout.' "

I wondered aloud if that's why the volume on television sets always seems either too loud or too soft.

"Probably. You've damaged the sensory nerves' ability to respond clearly to a wide range of volume levels. It's like trying to turn the volume up on a cheap transistor radio. The sound is either clear but too faint, or loud and distorted."

Another common symptom of sensorineural hearing loss, I learned, was the ringing I'd noticed in my ears. Will called it tinnitus.

Again, researchers don't know exactly why, but damaged nerves often begin to relay faulty messages, perceived as ringing, buzzing or whistling. If you've ever left a loud concert or put in a few hours behind a chain saw and noticed your ears ringing, that's tinnitus.

"Tinnitus is an early sign of hearing loss," Will said. "At first, it's usually temporary. Given a rest, ears can recover, up to a point. But if noise damage continues, the ringing becomes permanent."

"It never goes away?"

"I hate to say never. But in your case, after this much time, I have to say probably not. You won't recover the hearing you've lost, either. Sensory cells in the ear can't regenerate. Once they're gone, they're gone."

"Will it get any worse?"

"If you don't protect your ears, I'd say almost certainly. Besides, some amount of hearing loss is normal with age -- at least among people living in industrialized countries."

In the 1950s, audiologist Samuel Rosen tested the hearing of an African tribe tucked away in quiet isolation on the Sudanese-Ethiopian border, untouched by the roar of traffic or amplified music. Men well into their seventies, he found, could routinely hear sounds as faint as a murmur across a distance the length of a football field.

Few of us will be so lucky. By age 65, one in three Americans suffers hearing loss serious enough to interfere with communication. In one recent study, researchers found that some symptoms commonly blamed on Alzheimer's disease -- unresponsiveness and confusion, for instance -- can actually be the effects of hearing loss.

Among those fortunate enough to reach their nineties, nine out of ten will have impaired hearing.

And it looks like many of us won't have to wait that long. The Woodstock Generation

Back in 1969, the summer of Woodstock, audiologist David Lipscomb set about testing the ears of incoming freshmen at the University of Tennessee. Eighteen-year-olds are past the age of childhood ear infections that can dampen hearing but are still too young to be suffering the effects of aging. They should have the most consistently sharp ears around.

Researchers in the 1930s and 1950s had tested 18-year-olds to set the standard for what the human ear can hear. Lipscomb found that, by comparison, the Woodstock generation was in deep trouble. Nearly a third of the students tested showed signs of hearing loss. Among the male students, one in eight had damage severe enough to interfere with communication.

Rock-and-roll, most audiologists suspected, was to blame. Live concerts commonly reached sound levels above 120 decibels -- louder than a jackhammer or the roar of a chain saw. Until the 1960s, most hearing loss was associated with workplace noise -- an occupational hazard. Now, it seemed, people were going deaf just for fun.

And the fun kept getting riskier. In the early 1980s, audiologist Maurice H. Miller of New York's Lenox Hill Hospital was alarmed to hear the noise pouring out of his kids' Walkman-style stereo tape players. So he donned his white lab coat, grabbed a sound-level meter and set off into the streets of New York. Stopping anyone carrying a personal stereo, he measured sounds of 115 decibels and higher pouring out of tiny earpieces directly into vulnerable ears.

"Imagine you're riding a New York subway," Miller told me. "The sound level is about 100 decibels -- loud enough to have to shout over. The decibel scale, like the Richter scale for earthquakes, is logarithmic. So 110 decibels is 10 times as loud as that; 120 decibels is one hundred times louder than a subway car. That's enough to do permanent damage."

Miller is even more worried about customized car stereos that boast several speakers -- and sound levels that reach 130 decibels. "That's roughly the sound of a jet engine at takeoff. And believe me, we see the casualties in our clinic all the time -- people in their thirties and forties with the kind of hearing loss we used to see only in people past retirement."

Of course, noise-induced hearing loss occurs gradually over time, and few people are willing to admit they're growing hard of hearing -- a traditional hallmark of old age. Eyeglasses are stylish; hearing aids are not. The Exquisitely Sensitive Ear

A pin drops. The sound energy reaching our ears may equal no more than one-quadrillionth of a watt of power -- enough to move the eardrum less than the diameter of a hydrogen molecule. Yet if our ears are sharp, we hear it. Not only that, we can identify exactly what the sound is and precisely where it's located.

"Our ears are natural amplifiers, ingeniously constructed to boost incoming sounds as they're conveyed toward the inner ear," said Peter Dallos, neuroscientist at Northwestern University's Auditory Physiology Laboratory. I called him to learn why our ears are so vulnerable.

"In part it's because of the ear's exquisite sensitivity," he said. By the time a sound has passed through the tiny trio of bones in the middle ear, it has been intensified as much as 30 times. Then, in the inner ear's fluid-filled spiral chamber, called the cochlea, sound waves surge out across a springy membrane, like ripples across a pond. The membrane is lined with rows of sensory cells called hair cells. Depending on their position, they respond to different wave frequencies rippling through. Each hair cell acts like a switch, responding to movement by releasing chemicals that trigger nerves to send electrical signals racing to the brain.

"The outer row of hair cells seems to be especially vulnerable to noise damage," Dallos said. "Inner hair cells have about 90 percent of the nerve connections from the brain, so it's obvious that their job is simply to transmit sound signals. But those outer hair cells actually behave less like sensory cells than muscle cells." Indeed, in much the same way that your knee kicks out at the tap of a rubber mallet, these outer hair cells appear to give a little kick when they're stimulated by sound impulses, increasing the sound energy reaching the inner hair cells by as much as 40 decibels -- enough to make a faint whisper fully audible.

"We think outer hair cells may be the first to go. Exposing them to excessive sound energy is like exposing young trees to a gale-force wind. The force of the energy is enough to shake them apart. Eventually, the cells die and are replaced by scar tissue. The result," said Dallos, "is gradual, irreversible hearing loss."

What exasperates most audiologists is that it doesn't have to happen. As Maurice Miller told me, "We know how to prevent most forms of hearing loss. I can talk myself hoarse about it. But tell me, who's listening?"

I am -- or at least I'm trying to. Ever since that graph traced the notch in my hearing, I've been listening more than ever to the chatter of birds in the morning, the plink of distant pianos, the murmur of voices at a table nearby. I don't want to lose those sounds. Turn Down That Walkman

What's the best way to save your ears? It's ridiculously simple: Avoid loud noises. "If you have to shout to converse over background noise, it's too loud," Miller said. "And the sound is too loud if someone sitting next to you can hear the music coming out of your Walkman-style stereo." The biggest danger occurs when people turn up the volume in the headsets to drown out the background noise of a subway or airplane. Most have volume settings from one to 10. Four, according to Miller, is as loud as you should ever go.

Noise becomes more damaging the longer it lasts. A food processor spins out about 85 decibels -- nothing to worry about for a minute or two. But according to standards set by the Occupational Safety and Health Administration, exposure to sound levels of 85 decibels eight hours a day, five days a week, will eventually cause permanent damage in the most people. And each time you add five decibels of loudness, the time it takes to cause lasting injury drops by half. At 120 decibels -- rock concert volume -- the damage is done in less than half an hour.

Luckily, the ear can protect itself against some loud sounds: A membrane at the entrance to the inner ear tightens, dampening sound. But short bursts of loud noise, like an exploding firecracker, can take the ear by surprise -- causing more damage than continuous noise.

What's more, some ears do seem better able to withstand assault than others. In studies of factory workers exposed to uniform noise levels, some showed significant hearing loss over time, others none at all. Your susceptibility to ear damage, like so many other things, may be programmed into your genes. Hearing loss does seem to be handed down in families, but there's no sure way to tell if you're the next one in line.

Unfortunately, avoiding noise isn't always easy. If you're handy around the house, the whine of a power saw exposes you to sound levels of more than 90 decibels. Driving home with the windows rolled down and the radio turned up can be even louder. And if you're a sports fan, the sound of a cheering ballpark crowd can reach 120 decibels.

When you can't get away from noise, earmuffs or earplugs are your best bet. Earmuffs cover the ears completely and are routinely worn by airport runway personnel. They offer full protection.

Earplugs block out somewhat less sound, but they're much more wearable and more portable. The most popular over-the-counter version, made of soft foam that expands to fill the ear canal, costs about $2. For about $50, an audiologist can fit you with plugs specially molded out of plastic to match the shape of your ear canal. Earplugs are rated by how many decibels they cut. The custom-made plugs do the best job, lowering noise by about 35 decibels -- enough to turn even the loudest rock concert from dangerous to dulcet.

Some models are even stylish. A San Francisco organization called HEAR -- Hearing Education and Awareness for Rockers -- recommends ear protectors such as "Earshades," custom earplugs that come in 20 colors and can be decorated with feathers or dangling earrings. Last year, the outfit got a big boost from none other than Pete Townshend, who donated $10,000 to support HEAR's free screening clinic.

"There's a real need to get the message out loud and clear," explained Rebecca Meredith, an audiologist who works with HEAR. "Almost every musician I've tested over the past year shows some degree of hearing loss."

You don't have to be a rock-and-roller to be at risk. Sound levels in the percussion section of a symphony orchestra can be louder than a roaring subway train, peaking at more than 105 decibels. "More and more classically trained musicians are tucking earplugs in before the conductor raises the baton," said Meredith.

She keeps her own set of earplugs handy; her teenage daughter recently took up the drums. "You can imagine what my house sounds like when she's practicing," said Meredith.

I can. It has been two decades since my father shouted from the top of the stairs, but I remember. For now, I keep the stereo down to a volume that I can be heard over. I stay out of noisy clubs and loud restaurants. I've given up my Walkman-style headphones for a set of earplugs whenever I ride the subway or an airplane. And when my nephews visited recently with their newest toys -- portable boom boxes -- I gave them an earful. Sure, they nodded as my lips moved, but I wouldn't bet they really


Devices Are Getting Better

Only one in four people who could benefit from a hearing aid actually wears one, according to the National Hearing Aid Society. Vanity is one reason. But even people who give hearing aids a try may find themselves irritated by the tinny sound or background roar of the miniature devices. Hearing aids keep getting better, however. Here's what's available:

Behind-the-ear aids consist of a small microphone and amplifier unit that slips behind the ear. The units are about the size and shape of a prawn, so they're often called "shrimp" aids. Sound is conveyed through a clear plastic tube into a small earpiece tucked into the ear canal. Because they're big enough to hold a lot of circuitry, these aids tend to offer better sound than do smaller versions. Also, there's room for a larger, longer-lasting battery and a bigger volume control. One drawback: The microphone is outside the ear, where it can sometimes amplify wind noise. Children with hearing loss almost always receive behind-the-ear models, which account for 21 percent of all hearing aids sold. Cost: $600 to $750.

In-the-ear aids pack microphone and amplifier into a single crescent-shaped unit that fits snugly into the curved hollow at the opening of the ear canal. Because the microphone is right in the ear, there's less likely to be a problem with wind interference. Conspicuous but fairly easy to adjust and service, these aids usually cost between $550 and $800. Batteries must be changed every three weeks.

In-the-canal aids are even smaller -- so tiny that they fit into the ear canal itself, where they're nearly invisible. About 77 percent of all hearing aids are either in-the-ear or in-the-canal models. All use customized electronic circuits to shape the amplification to match individual hearing loss. That's important, since noise-induced loss usually affects only certain frequencies. However, the miniature controls and batteries of in-the-canal aids can make trouble for any but the most nimble fingers -- and the units are comparatively expensive: $700 to $800.

Programmable hearing aids go a step further, offering from two to eight different settings, each designed to shape the amplification for a specific situation -- the sound of conversation at a noisy party, for instance, or a single voice in a quiet room. Cost: $1,200 to $1,500.

Smart hearing aids use computer chips to sort through the incoming sounds and automatically boost only the ones that need boosting. These use digital technology, which converts sound waves to numerical values -- giving audiologists extreme flexibility in setting the aid for just those frequencies the ear has lost. Like digital compact discs, the sound can be cleaner. The only fully digital aid now on the market is the size of a cigarette pack and must be carried in a pocket. It costs about $2,500.

Can You Hear This?

Are your ears as sharp as they once were? Do you have trouble following conversations in noisy rooms? Do you feel that other people set the volume of televisions and stereos too low?

Try this do-it-yourself test suggested by one ear specialist: Hold your hand up next to your shoulder as if you're taking a courtroom oath, then rub your thumb and forefinger together. If you don't clearly hear a high-pitched scratching sound, you may have some hearing loss in that ear.

Then again, you may not. Unfortunately, the only truly reliable hearing test is one given by an audiologist or other ear specialist -- though if your hearing isn't now bothering you, it's probably not worth the trouble. A quick way to find out if you should consider a real audiology exam is to take this simple telephone screening test.

Dial 1-800-222-EARS between 9 a.m. and 6 p.m. eastern time to reach a national operator who'll give you a number in your region. (Exceptions: In Pennsylvania, dial 1-800-345-EARS; in Canada, 1-215-359-1144.) The call to the operator is free (in the United States). The regional call for the test itself (two minutes) may be long distance and will be charged at standard rates.

{In the District, call 296-8378. Within 30 miles of Columbia, Md., call 995-1959. A Virginia number will be set up by the end of the year.}

An answering machine runs the test. It's crucial that you call from a quiet place, away from the TV, stereo, air conditioner or voices. You'll be told to listen for four faint tones in each ear.

If you fail to hear all eight tones, don't worry. Try the test again in a day or two -- even perfectly normal ears vary in sensitivity from day to day. What's more, noise nearby or static on the line may interfere with the recording, masking tones you could otherwise hear. Don't call from a cordless or cellular phone.

The test isn't perfect. It's best at identifying people with significant hearing loss at middle and low frequencies, below 3,000 hertz. If you hear all the tones but still think you're showing some signs of a hearing problem, see a doctor.

It's Not Just Noise Everything from earwax to common childhood diseases can endanger hearing. Here are some of the hazards and what can be done about them:

Wax buildup. Earwax is there for a good reason -- to keep water, bacteria and viruses away from the delicate skin of the ear canal. But if too much collects in the canal, it can muffle hearing. Kits with a rubber syringe and solution to flush out excess earwax are available at drugstores. But be extremely careful. Many specialists recommend against do-it-yourself treatments, which can force wax deeper into the ear. If you think accumulated wax might be dulling your hearing, see your doctor.

Eardrum injury. Cotton-tipped swabs have caused so many accidental eardrum punctures that most experts say they should never be used for ear cleaning. A hard blow to the head also can rupture the eardrum or disrupt the middle-ear bones that conduct sound to the inner ear. Likewise, scuba diving can burst the eardrum or other ear membranes if the diver has an allergy, cold or infection that swells shut the eustachian tube (the middle ear's ventilation duct), allowing pressure outside the ear to greatly exceed that inside.

Ear infections. Middle-ear infections in children are a leading cause of temporary hearing loss. In serious cases, inflammation closes the eustachian tube, permitting fluid and pressure to dampen sensitivity of the paper-thin eardrum. Hearing usually returns to normal when an infection clears. But severe infections can rupture the drum and, if they recur repeatedly, may cause scarring and permanent hearing loss. Many conditions, ranging from mumps and measles to diphtheria, also can cause damage.

Adults who swim regularly also are prone to infections, dubbed "swimmer's ear." Doctors suggest special earplugs, which cost about $3 at sporting-goods stores.)

Antibiotics. Some prescription drugs can be ototoxic -- poisonous to the ear. In strong doses, they may destroy the inner ear's sensory cells. Among the most common ototoxic drugs are the antibiotics streptomycin, gentamicin and tobramycin, as well as several compounds used in cancer chemotherapy. Doctors prescribing these treatments should carefully watch for early signs of hearing loss. Aspirin is also ototoxic, although far less so. It can cause temporary tinnitus and may temporarily worsen the ringing in people with permanent tinnitus. If your ears ring after taking aspirin, try acetaminophen. Caffeine and nicotine also seem to worsen tinnitus.

Clogged arteries. By choking off blood flow to the inner ear's sensory cells, blood vessel constriction, such as that caused by a diet high in fat and cholesterol, may aggravate noise-induced damage. So can the artery constriction often associated with high blood pressure.

Peter Jaret is a contributing editor for In Health magazine, from which this article is excerpted.

1990 Hippocrates Partners.