How does hearing work?

Sound travels to your outer ear and is then funneled into the ear canal. The sound strikes the eardrum, which then vibrates. That vibration forces three bones in the middle ear to begin rocking, one after another, transmitting the motion to the inner ear. There, tiny hair cells become stimulated and arouse the auditory nerve. That nerve then delivers a signal to the brain, which recognizes the signal as sound. Pictured here (above, left) is a hearing aid that fits inside the ear canal. Also pictured is a hearing aid that is worn outside the ear.

What are my choices when buying a hearing aid?

Shopping for a hearing aid can be bewildering. Digital vs. analog? Behind-the-ear vs. in-the-ear? It isn't even clear where you should buy a hearing aid — from an audiologist, a hearing-aid dispenser, a Web site?

Hearing aids also can be expensive. Medicare and most insurance carriers do not cover hearing aids. A deluxe model with digital components can cost more than $3,000.

It is impossible to illuminate every nook and cranny of the hearing-aid world. But if you are shopping for a hearing aid, here are some of the questions you'll probably ask as you make your purchase.

Do I even need a hearing aid?

The choice is yours on whether to get a hearing aid. But a hearing test can help you make an informed decision. Unfortunately, many people are in such strong denial about their hearing loss or worry that a hearing aid will make them look too old that they avoid getting the test. Without really recognizing it, these people may cut themselves off from the world because they can't hear normal speech properly. Normal conversation becomes a strain. These people avoid going out to restaurants. And parties can become intimidating jumbles of noises.

Hearing loss is common, especially as people get older. About one-third of Americans aged 65 to 75 have some hearing loss. The fraction only gets larger as people get into their 70s and 80s. Yet studies estimate that only 20 percent of people who would benefit from a hearing aid wear one.

The medical term for this age-related hearing loss is presbycusis (pronounced prez-bee-ah-CUE-sis) from the Greek presbys for old man and akousis for hearing. Presbycusis most often starts with an inability to hear high-frequency sounds. Because of the way English is spoken, English speakers with a loss of high-frequency hearing can find it extremely difficult to understand conversation, especially when there is background noise.

Admittedly, it's more complicated than this. After all, some people do mumble. But a telltale sign of people struggling with diminished hearing is the frequent complaint that although they can hear people just fine, they can't make out what they're saying.

Hearing Tests

If you suspect you have a hearing problem, you should see a physician. You can go either to an otolaryngologist — a doctor who specializes in ear, nose and throat problems — or to an otologist, a doctor who specializes just in ears. The doctor will examine your ears and ask you about the pattern of your hearing. After ruling out some sort of obvious obstruction or major ear infection, most doctors will use a tuning fork to make a preliminary assessment.

Tuning-fork tests help doctors figure out whether you have the same amount of hearing loss in each ear and if that hearing loss is conductive or sensorineural. Conductive hearing loss means that there is some kind of physical blockage in the ear: It might a chunk of earwax, a cyst or a birth defect. Sensorineural hearing loss is far more common and is most often the result of damage to the tiny hairs in the inner ear that translate the energy from sound waves into a nerve impulse.

If a physician confirms that you have a hearing problem, he or she should refer you to an audiologist for a full battery of tests, called an audiogram. Essentially, the audiogram charts how soft (measured in decibels) a sound you can hear at range of different pitches (measured in hertz). It also measures how accurately you understand spoken words (discrimination).
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High-Frequency Hearing Loss

Sound is complicated, but the two basic components are volume (measured in decibels) and pitch (measured in hertz). Age-related hearing loss most often results in an inability to hear high-pitched sound. That can interfere with a person's ability to make out everyday spoken English. Here is why.

Most people say sounds formed by "f," "s" and "sh" at a fairly high pitch (4,000 hertz). They say sounds formed by vowels and consonants such as "m," "n" and "z" at a fairly low pitch (300 hertz or so). Sounds formed by "p" and "h" fall in the middle (about 1,000 hertz). When people lose their ability to hear high-pitched sounds, they miss or have to guess at what is said. Tests would measure this loss as a decrease in discrimination. For these people, common talk turns into a garbled mess.
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Do I need to buy one hearing aid or two?

Because hearing aids are expensive, one of the first questions that novice buyers have is whether they need a hearing aid for both ears, according to Jeffrey S. Martin, M.A., CCC-A, an audiologist at Brigham and Women's Hospital in Boston. The degree of hearing loss in each ear can vary greatly, especially in cases when the loss is the result of a birth defect or an accident. Of course, people with hearing loss affecting only one ear generally need only one hearing aid.

But, as Martin notes, most people with age-related hearing loss experience it in both ears. For them, it is usually better to get an aid for each ear. Two aids create a balanced sound. They also help people figure out where a sound is coming from — what hearing specialists call "localization."

What size and style hearing aid should I buy?

Trying to make a decision about size and style is where the real confusion about hearing aids starts to set in. This is an area in which vanity can steer people astray, according to Bonnie Forman-Franco, M.A., F.A.A., CCC-A, an audiologist and owner of Plainview Hearing Center in Plainview, Long Island, New York. "They get drawn into the emotional and cosmetic appeal, when a different style, such as a behind-the-ear model, would have been more appropriate," she says.

On the other hand, no one would deny that how the hearing aid looks and feels is legitimately important.

One good way to inject some clarity into this area is to separate size and shape from the circuitry of the hearing aid. The circuitry is the machinery within the hearing aid that processes sound. There are two basic choices in circuitry: digital and analog. The size and shape of the hearing aid are independent of the circuitry inside. Put another way, hearing-aid manufacturers can fit any kind of circuitry into almost any size hearing aid.

Martin says one of the big misconceptions among new hearing-aid purchasers is that a small hearing aid means a digital hearing aid. But small does not necessarily mean digital.

Regarding the size and shape of a hearing aid, people need to first decide between a behind-the-ear model and an in-the-ear model.

With today's technology, behind-the-ear aids are small, powerful and easy to handle for cleaning, changing the battery and adjusting the volume controls. So although they are more noticeable than in-the-ear aids, behind-the-ear aids are user-friendly and can provide more volume when needed.

Forman-Franco also thinks that behind-the-ear models are more durable than in-the-ear models, partly because they aren't exposed to the ear's wax and moisture. To make behind-the-ear aids last even longer, some people put little rubber covers on them that are jokingly referred to as condoms for hearing aids.

The in-the-ear models come in a variety of shapes and sizes. Some are plainly visible and fill the entire, bowl-shaped part of the outer ear. Others can hardly be seen and fit almost completely in the ear canal. However, these completely in-the-canal models don't have manual volume controls or a feature that allows the wearer to push a button to adjust the hearing aid to avoid feedback from the telephone.

Martin says a person's dexterity must be factored into the choice of an aid's size and shape. Consider the fact that hearing aids must be taken out at night. It would be a mistake, he says, to buy a small hearing aid if it's a struggle getting it in and out of the ear.

The price of a hearing aid varies with the circuitry inside, but as a rule, the smaller the hearing aid, the more expensive it will be. The most expensive behind-the-ear model will run you about $2,500, whereas the smallest completely in-the-canal model with digital circuitry can cost about $3,500.

Is digital circuitry worth the money?

Type Of Circuitry	Price Per Hearing Aid
Analog	$600-1,300
Programmable Analog	$1,300-1,800
Digital	$2,200-3,300

Digital circuitry adds about $1,000 to the cost of a hearing aid. What are you getting for that money?

Basically, the digital aids contain a tiny computer that chops up sound into bits of information and then manipulates that information in numerous ways. Analog circuitry conveys sound without "digitizing" it into bits of information. Even the most basic analog models, however, can be adjusted to boost certain frequencies such as the high-pitched sounds that people with age-related hearing loss tend not to hear well.

Midway between basic analog hearing aids and digital models are programmable analog hearing aids. Many people mistake these aids for digital hearing aids because some of the controls are adjusted with the help of a computer. But sound itself is not processed digitally. Yet these hearing aids have different programs that adjust the aid to the telephone, noisy environments, and so on. Sometimes the wearer can switch from program to program with a push of a button on the hearing aid itself. Other models come with a remote control similar to a TV remote.

Some audiologists believe that digital aids are easier to fine-tune to an individual than the analog aids because the digital circuitry allows for very small adjustments. These adjustments result in "sound comfort." And because some aspects of the digital aids are automatic, such as volume control, some people find them very easy to use.

Keep in mind, however, that some of those same automatic adjustments are part of programmable analog hearing aids. Some hearing-aid researchers say patients need to be wary of the "it's digital, it must be better" mindset. Although these experts are optimistic about the potential of digital technology and the promise of "real-time" processing of sound, they don't believe that digital sound processing, as currently applied, holds any proven advantage over analog sound processing. Lynn Luethke, Ph.D., a program director at the National Institute on Deafness and Other Communication Disorders, notes that a panel of experts recently convened by the institute did not believe that a clinical trial of digital hearing aids was warranted.

But preferences in hearing aids are individual. Some people like digital hearing aids perhaps, in part, because they have a preconceived notion that digital sound processing is more up-to-date. Yet for many people, analog hearing aids are just fine and a good deal cheaper. In addition, people who have worn analog hearing aids sometimes find they don't hear as well when they switch to the more expensive digital models.

What else should I consider when buying a hearing aid?

Russell Janus, 48, an accountant who lives in Pembroke Pines, Fla., has worn hearing aids for more than 30 years. When it comes to hearing aids, he's tried them all: "You name them, I've had them." What he really likes about his current set of hearing aids are the directional microphones, combined with a feature called sound compression. "I love them," says Janus. So do many other people. Dual-microphone hearing aids usually have one microphone that collects sound from all around and another that points forward to collect sound that is coming from in front of the wearer.

Where should I buy my hearing aid?

In most states, two kinds of specialists are licensed to fit you for a hearing aid: audiologists and hearing-aid dispensers, who are sometimes called hearing-instrument specialists. Audiologists must have a master's degree and are licensed to evaluate hearing, as well as to fit people with hearing aids; many are affiliated with hospitals and schools. Hearing-aid dispensers usually are licensed only to sell and fit hearing aids.

You also should consider the business arrangements that some audiologists and dispensers have with hearing-aid manufacturers. Some have very tight ties with certain companies. They may work on commission or get rewarded in other ways for selling a certain number of a particular brand of hearing aid. Others are more independent.

Usually, these business arrangements aren't disclosed. And it can be awkward asking about them. You may not get a straight answer even if you were to ask. Perhaps the best approach is just to be aware of salesmanship. Most of us can tell when someone is selling us something. There is also no harm in asking a few pointed questions.

Some chains opened up recently that are the hearing-aid equivalent of a large home-improvement store: low prices in exchange for, perhaps, less service and less personalized attention. Several hearing-aid Web sites are operating on the same basic premise. Understandably, audiologists and hearing-aid dispensers operating as small businesses aren't happy about this competition.

The value of good service and personalized attention provided by conventional audiologists and dispensers is high, particularly for the new hearing-aid wearer. The value may very well be a whole lot less important to someone who already knows a great deal about hearing aids — someone like Russell Janus, the Florida accountant, who says he bought his last pair of aids from one of the new chains and is doing well with them. Buying locally can be a benefit, though, when something goes wrong with the aid. Many problems can be solved with a quick trip to the audiologist, rather than mailing the aid back to the Internet company.