Most hearing-aid purchases go off without a hitch. But some don’t. It’s not easy to get things right because each patient’s hearing loss is unique, and every patient has different expectations. Even two patients who have the same hearing loss on paper may have very different rehabilitative needs.

Also tricky: Since most hearing aids sold by local hearing specialists are custom-molded, patients can’t feel exactly how various makes and models would fit in their ears. But it is possible to try different technologies. Many BTE models with disposable earpieces can be fitted with special pliable earpieces and then set up for tests. The sound quality in the test should be fairly close to what you’ll get with your own customized device. But ultimately, time and experience with a particular hearing aid are the only ways to determine how well it works for you.

For aids bought from hearing specialists, Delaware and Pennsylvania law protect consumers from being locked into hearing-aid purchases that do not meet their needs.

According to Delaware law, for 30 days after selling a hearing aid the dispenser is required to adjust, repair, or replace it—without charge—if requested to do so by the buyer. During this 30-day period, if requested to do so, the seller is also obligated to accept the hearing aid as a return and refund the total amount paid for the product and service, including the cost of an exam, fitting, or other services connected to the sale of the hearing aid.

In Pennsylvania, if requested to do so, all hearing aid dispensers are obligated to accept a hearing aid as a return within 30 days of purchase and refund the charges for the hearing aid. Dispensers are not obligated to refund the cost of an exam, fitting, or other services connected to the sale of the hearing aid, and are also allowed to charge a reasonable restocking fee; if a dispenser considers these fees nonrefundable, it must clearly state so on the original bill of sale.

New Jersey did not at the time of this writing have a law requiring hearing-aid dispensers to accept hearing aids as returns for refunds, but many dispensers do nonetheless offer at least 30-day trial periods. Be sure to get the refund policy in writing.

It’s unclear whether these laws will apply to OTC models; they probably won’t.

Some specialists offer trial periods more generous than 30 days. Some allow 60 days or more for wearers who have special needs or who have bought particularly complicated hearing aids. If you feel you might need extra time to decide, ask the dispenser if an extension is possible and get the dispenser’s promise in writing. But keep in mind you’ll likely face a time limit: The FDA considers hearing aids “used” 90 days after they’re sold, and few sellers will take them back at that point.

Hearing-aid specialists usually offer a free adjustment period during which they’ll provide assistance. This period varies, with some sellers offering free adjustments for six months and others for the life of the aid. If you are buying a hearing aid for the first time, or trying a new type of aid, find out about the dispenser’s policy regarding follow-up appointments.

Also, find out whether your return period will be extended if adjustments are necessary; if so, get this promise in writing. You don’t want to lose your right to return an aid simply because you’ve spent weeks trying to get it adjusted to meet your needs before concluding that it just doesn’t suit you.

To back up newly purchased aids, most manufacturers provide warranties of one or two years. In most instances, you can buy an extended warranty too.

You can also buy hearing-aid insurance to cover damage or loss, either as a manufacturer’s warranty add-on or as a separate policy. A hearing-aid dispenser should have insurance information; also check with your homeowners insurance carrier—you may be able to add a personal articles floater for hearing aids to your policy. Before buying any insurance, compare its premiums to the price of the aid. Usually, it’s not a good value.

With luck and effort, you won’t need to buy new hearing aids that often—the average lifespan of new models is five years. By keeping yours clean and maintained, it will likely last longer.