Hearing that fades with age does not announce itself. It usually starts with the softer, higher sounds of speech, the s, f and th that tell one word from another. Voices stay loud enough, but words start to blur, and the natural conclusion is that other people have started to mumble.

It is also far more common than most people think. The National Institute on Deafness and Other Communication Disorders (NIDCD) reports that about one in three people between 65 and 74 has hearing loss, and nearly half of people older than 75 have difficulty hearing. Because it creeps in over years, family members are often the first to notice: the TV is louder, questions get repeated and phone calls get shorter.

There are now two ways to get a hearing aid in the United States. The FDA allows adults 18 and older with perceived mild to moderate hearing loss to buy over-the-counter hearing aids in stores and online, with no exam, prescription or fitting appointment. You set them up yourself, often with a phone app.

The other way is a prescription hearing aid, chosen and programmed by a licensed professional after a hearing test. It suits people with more severe hearing loss, people who want hands-on help with fitting and follow-up, and anyone with a warning sign. A simple rule of thumb: if quiet one-on-one conversations are still clear and the trouble is mostly in noise, the OTC range is worth a look; if even quiet talk is hard, start with an evaluation.

Some changes should not be handled with a device bought off the shelf. The FDA lists warning signs that call for a licensed health care professional first, including hearing loss that came on suddenly or got worse quickly, hearing loss or ringing in only one ear, pain or discomfort in the ear, fluid or blood coming from the ear, and dizziness or vertigo together with hearing changes.

Sudden hearing loss is treated as urgent by doctors. If it happens, contact a health professional the same day rather than waiting to see whether it improves on its own.

Most hearing aids sit either behind the ear, with a small tube or wire into the ear canal, or inside the ear itself. Behind-the-ear models are easier to handle; the smallest in-the-canal models are harder to see but also harder to adjust with stiff fingers. The NIDCD hearing aid page shows the main styles side by side.

Beyond style, the differences people notice day to day are rechargeable batteries versus small disposable ones, how well the device handles background noise, whether it streams phone calls, and whether it has a telecoil for the loop systems used in some theaters and places of worship.

According to Medicare.gov, Original Medicare does not cover hearing aids or the exams for fitting them. Part B can cover a diagnostic hearing exam in certain situations, such as when a doctor orders it to find out whether you need medical treatment.

Some Medicare Advantage plans include hearing benefits, and the details vary a lot from plan to plan: an allowance per ear, a provider network, routine exams or none of these. The only reliable answer is the one your plan gives you in writing.

Medicaid coverage for adult hearing aids depends on the state. Veterans enrolled in VA health care may be able to get hearing aids through the VA. If you have a health savings account or a flexible spending account, IRS Publication 502 lists hearing aids, and the batteries and repairs that keep them working, among medical expenses.

When you compare prices, compare the whole package: the device, the testing and fitting, follow-up visits, the trial period, the warranty and the cost of batteries. The lowest number on the box is not always the lowest total cost.

The first days can be surprising. Footsteps, rustling paper and the hum of the fridge come back, and your own voice may sound odd. That is normal: the brain is relearning sounds it has not processed clearly for a while. Wear the devices at home for a few hours a day first, then add quieter outings, and leave the noisiest places for last.

Use the trial period on purpose. Keep the return deadline where you can see it, and if a device hurts or you still struggle after a few weeks, talk to a hearing professional before the window closes.