- Is it really necessary to wear two hearing aids, or can I get by with one?
- Why do your hearing aids cost so much?
- What should new hearing aid users really expect?
- Why does my voice sound so odd to me when wearing hearing aids?
- How much time is needed to adapt to hearing aids?
- What can I do about the whistling (feedback) produced by my hearing aids?
- How often must hearing aids be replaced?
1. Is it really necessary to wear two hearing aids, or can I get by with one?
There are four main reasons why binaural (two eared) listening is superior to monaural (one eared) listening. They are:
- Better Hearing in Noise: An individual’s hearing in noise can be improved if the signal reaching each ear arrives at a slightly different moment in time. This is technically referred to as phase. When the brain receives slightly different, yet still audible signals at the two ears, it has the ability to cross-correlate and process the primary signal (usually speech) better than if the signal is received monaurally.
- Improved Signal versus Noise Level from Optimizing Position: Sound loses intensity (loudness) when it travels across the head. This occurs mostly for the high frequencies which are the most important for understanding of consonants, such as /s/, /t/, /f/, and /sh/. If you have a hearing aid on only one ear, say the left one; and the person you wish to hear is speaking to you from the right side, the consonants may be decreased by nearly 20 decibels by the time it gets to your aided ear. Unfortunately, noise in the room may occur from any or all directions, so while the noise level is not decreased, the speech level is. Wearing two hearing aids ensures that the speech sounds will not be diminished any more than necessary because of your position in the room.
- Improved Localization Ability: We determine where a sound is coming from on the basis of the relative time in which the sound arrives at each ear, the relative difference in loudness at the two ears, and the relative difference in the pitch of the sound at the two ears. When there is a large difference in hearing between two ears (as might occur when a person with similar hearing in both ears only wears one hearing aid) the brain cannot make use of these subtle relative differences and their ability to locate sounds may suffer.
- Possible Deterioration of the Unaided Ear: We hear in our brain, not in our ears. The ultimate goal of hearing aids is not just to send sound into the ear. It is also essential to retrain the central auditory system in the brain. While it is uncertain whether hearing sensitivity (ability to hear soft sounds) will decrease if your ear is not stimulated adequately, research now suggests that there can be changes in the way in which your brain processes sound when it is “starved.” Thus, providing stimulation may be important in preserving your auditory potential.
2. Why do your hearing aids cost so much?
There are many factors that affect the cost of hearing aids:
- They are sold in relatively low volume per year (i.e. approximately 1.7 million hearing aids for some 30 million hearing impaired), as compared to several million stereos or televisions. Computers used to cost considerably more than they do now. The biggest reason they are relatively inexpensive now is that they are sold in greater volume.
- The amount of time and money spent by manufacturers on research and development is considerable. One manufacturer claims to have spent over twenty million dollars developing a single model. This is a considerable investment considering the sales volume that is typical for hearing aids.
- The amount of time spent by a provider with a patient is very significant. Data indicate that an average of five direct contact hours is spent during the first year a patient receives hearing aids. This time is critical for new users, particularly to assist during the acclimatization process. Without the assistance of a qualified and experienced professional who can adjust the technology to a patient’s individual needs and provide important advice and counseling in the first few months, new technology users often find themselves discontinuing use or even returning their technology because they do not perceive that their needs are met. The investment made in the discarded technology is wasted because the technology does not perform to expectations.
3. What should new hearing aid users realistically expect?
Remember that hearing aids do not fix hearing impairment, especially in the case of sensorineural hearing loss with poor speech discrimination. Keeping that in mind, you should see improvements. When wearing hearing aids, your hearing in quiet environments, such as during one-on-one communication or watching television, should be improved. Your hearing in moderate background noise should be improved. Your hearing in moderate background noise is NOT going to be as good as your hearing in quiet. Your hearing in loud background noise should be NO WORSE than without the hearing aids. Soft speech should be audible, average speech should be comfortable; loud speech should be loud, but never uncomfortable. The hearing aids or earmolds should fit comfortably in your ears. Your own voice should be “acceptable” to you. There should be no feedback when the hearing aids are properly seated in your ears. You may hear sounds you have not heard for a while, like footsteps or the refrigerator humming. This is not abnormal. Be patient. It requires time to adjust to hearing aids. Your listening skills should improve gradually as you become accustomed to amplification.
4. Why does my voice sound so odd to me when wearing hearing aids?
Some hearing aid users report that they feel as if they are in a barrel or experiencing an echo when talking. This is called the occlusion effect. Normally, when your ear is unblocked and you are speaking, you hear yourself both through the air traveling through your ear canal, (air conduction) and through vibrations that you create in your skull and ear canal (bone conduction). When your ear is occluded or blocked, however, air conduction transmission is reduced and bone conduction perception enhanced. Try this experiment. Hum aloud and then alternately plug and unplug one ear while humming. Notice how the sound changes pitch and loudness in your plugged ear? This happens because the vibrations are blocked from their usual escape route. Most patients adapt to this effect and it isn’t a problem. Some have more trouble and require further modification and adjustment of the hearing aid. The important thing to ask yourself is whether or not the sensation is bothersome enough that you may not be able to adapt to it.
5. How much time is needed to adapt to a hearing aid?
While each person’s experience will vary, hearing aids may allow a person to experience certain sounds they may not be used to hearing. Relearning takes place in the central auditory nervous system and not in the ear itself. Recent experiments suggest that a listener’s ability to comprehend speech may continue to increase over a period of several months when wearing a new amplification system. This process is termed acclimatization. In most studies, the initial acclimatization period is two months (60 days).
6. What can I do about the whistling (feedback) produced by hearing aids?
There are two types of acoustic feedback:
- That are produced internally from the hearing aid – indicating a device in need of repair; and
- The more common external feedback produced by a leakage of amplified sound out of the ear canal and back into the microphone of the hearing aid.
Feedback that occurs when the hearing aid is being inserted or removed or when your hand is cupped near the device is common, and does not necessarily signal the need for action. If however, you experience feedback when you speak, chew, yawn or change position, you need to consult your provider. Usually, external feedback can be corrected by properly reinserting the hearing aid or earmold, remaking the earmold (or in-the-ear shell), plugging or reducing the diameter of any vents, altering the sound by means of filters in the hearing aids, changes in the way the devices are programmed, or adding a canal lock to better hold hearing aids in place so they don’t work their way out of the ear canal as you chew. Most of the more recent technology has some kind of digital feedback reduction. With this technology, feedback is sensed and eliminated by the hearing aid’s computer chip.
7. How often must hearing aids be replaced?
Generally speaking, hearing aids should last for at least five years. But that is the individual patient’s decision to make. One reason to replace a hearing aid is that, as we continue to age, our ears continue to grow and change shape. While your hearing aid may have been a good, tight, comfortable fit five years ago, now it may be loose and no longer making a good seal against the ear. Another reason is that the ear is a very hostile environment for the electronic components in a hearing aid. Manufacturers have made advancements in recent years that have made these components more durable, but even these sturdier components will begin to break down and require frequent repair after prolonged exposure to the moisture and wax in the ear. In these cases, the investment in new technology might be worth eliminating the frustration of having to send your technology to a repair lab every 45-90 days. Another common cause for replacement is that hearing losses tend to progress, especially after several years. The most popular hearing aids sold are designed for mild to moderate losses and cannot produce the amplification needed for a severe or profound loss. Once a hearing aid is “maxed out,” the only way to get more volume is with a new hearing aid.