You may have hearing loss and not know it. Here’s what it sounds like.

Hearing loss can be gradual and difficult to notice, but experts say hearing checks should be a routine part of health care.

The problem with identifying hearing loss is that many people don’t know what they are missing.

One study found that about 24 percent of people between the ages of 20 and 69 who think they have excellent hearing actually have measurable hearing damage.

To keep track of hearing health, audiologists say people should take hearing tests annually, like any other regular health checkup.

After a hearing test, you may be given a chart called an audiogram, which gives you detailed information about the status of your hearing in both ears.

Audiograms show how well — or poorly — you hear sounds at different frequencies, or pitches, providing a visual representation of how you hear the world.

The horizontal axis of an audiogram maps the pitches that are audible to your ears, from low-pitched sounds, shown on the left, to high-pitched sounds, shown on the right.

Water dripping from a faucet into a sink would represent a low-pitched sound on the left of the chart. A small chirping bird would register as a high-pitched sound on the right.

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The vertical axis on your audiogram shows how loud a sound needs to be for you to hear it well. Sounds at the top of the chart are quiet, while sounds at the bottom are very loud.

A blaring ambulance siren would appear at the bottom of the chart.

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When a person is speaking, the frequency and loudness of the sounds they make typically fall in a “U” shape in the center of the audiogram.

The audiogram of a person with normal hearing might look like this, showing that they can hear soft sounds that fall between 0 and 20 decibels.

The area in blue shows the frequencies and decibel levels a person can hear. The area above indicates the range of sounds they can’t hear.

Press play to hear how these hard-to-distinguish words sound with normal hearing.

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Two people with the same level of hearing loss can hear the world in very different ways, depending on which frequencies they are struggling to hear. This animation shows how hearing can move from normal to a mild, moderate or profound high-frequency hearing loss.

Someone with a moderate level of high-frequency hearing loss has more trouble with higher-frequency sounds, such as “s” or “th” sounds. Certain words may sound less clear to them.

Press play to hear how these hard-to-distinguish words sound with high-frequency hearing loss.

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Someone with a moderate level of low-frequency hearing loss would have the opposite problem — they struggle to hear lower-pitched sounds. Some words may sound tinny or harsh.

Press play to hear how these hard-to-distinguish words sound with low-frequency hearing loss.

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Some people experience hearing loss at middle frequencies. They might have trouble with hearing certain speech sounds that fall into this range. This is called a “cookie bite” hearing loss and might make words sound muffled.

Press play to hear how these hard-to-distinguish words sound with ‘cookie bite’ hearing loss.

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Hearing aids work by amplifying sounds at specific frequency channels, with the aim of giving wearers the ability to hear a more normal range of sound.

Once you know your audiogram profile, you can shop for a hearing aid that will optimize sound for the specific type of hearing loss you have.

An in-person hearing test with an audiologist gives the most accurate results, said Sarah A. Sydlowski, an audiologist with the Cleveland Clinic. An audiologist also can diagnose the source of a hearing loss, which, in some cases, could be fixable, she said. Health insurance doesn’t always cover this service, which typically costs around $100-$150 out-of-pocket.

Another option is to try a hearing center run by hearing aid specialists, such as at Costco or Sam’s Club, which often offer a free or discounted hearing test, but may try to persuade people to buy their products afterward. Hearing aid specialists can’t offer a full medical or diagnostic exam but can run hearing tests for the purpose of fitting hearing aids.

If an in-person or telehealth test is not an option, there are some online tests that can give fairly accurate results and could be used as screeners, according to experts.

Anyone with a hearing loss should treat it, experts said. Untreated hearing loss can result in changes in the brain that make it harder to hear even after getting hearing aids, said Heidi Hill, an audiologist with Hearing Health Clinic in Osseo, Minn.

“The parts of their brain that process sound slow down and go a bit dormant,” she said.

Research also shows that untreated hearing loss is associated with increased risks for falling, dementia and heart attacks, and has been linked with more hospitalizations, emergency room visits and higher medical bills.

Someone with a mild or moderate hearing loss may be able to buy hearing aids over the counter. Here’s a guide to help you choose the right one. For people with more significant hearing loss, experts recommend going to see an audiologist because they will probably need more powerful, complex hearing aids that are required to be professionally fit.

Garland Potts and Ariel Plotnick contributed to this report.

Laura Sinnott, audiologist and head of devices at Tuned, a hearing health company, provided audio and consulting for this story.

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