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A hearing aid magnifies sound vibrations entering the ear. Surviving hair cells detect the larger vibrations and convert them into neural signals that are passed along to the brain. The greater the damage to a person’s hair cells, the more severe the hearing loss, and the greater the hearing aid amplification needed to make up the difference. However, there are practical limits to the amount of amplification a hearing aid can provide. In addition, if the inner ear is too damaged, even large vibrations will not be converted into neural signals. In this situation, a hearing aid would be ineffective.
Analog aids convert sound waves into electrical signals, which are amplified. Analog/adjustable hearing aids are custom built to meet the needs of each user. The aid is programmed by the manufacturer according to the specifications recommended by your hearing care professional. Analog/programmable hearing aids have more than one program or setting. A hearing care professional can program the aid using a computer, and the user can change the program for different listening environments…from a small, quiet room to a crowded restaurant to large, open areas, such as a theater or stadium. Analog/programmable circuitry can be used in all types of hearing aids. Analog aids usually are less expensive than digital aids.
Digital aids convert sound waves into numerical codes, similar to the binary code of a computer, before amplifying them. Because the code also includes information about a sound’s pitch or loudness, the aid can be specially programmed to amplify some frequencies more than others. Digital circuitry gives a hearing care professional more flexibility in adjusting the aid to a user’s needs and to certain listening environments. These aids also can be programmed to focus on sounds coming from a specific direction. Digital circuitry can be used in all types of hearing aids.
You and your hearing care professional should select a hearing aid that best suits your needs and lifestyle. Similar to other equipment purchases, style and features affect cost. However, don’t use price alone to determine the best hearing aid for you. Just because one hearing aid is more expensive than another does not necessarily mean that it will better suit your needs.
A hearing aid will not restore your normal hearing. With practice, however, a hearing aid will increase your awareness of sounds and their sources. You will want to wear your hearing aid regularly, so select one that is convenient and easy for you to use. Other features to consider include parts or services covered by the warranty, estimated schedule and costs for maintenance and repair, options and upgrade opportunities, and the hearing aid company’s reputation for quality and customer service.
Become familiar with your hearing aid’s features. With your hearing care professional present, practice putting in and taking out the aid, cleaning it, identifying right and left aids, and replacing the batteries. Learn to adjust the aid’s volume and to program it for sounds that are too loud or too soft. Work with your hearing care professional until you are comfortable and satisfied.
You may experience some of the following problems as you adjust to wearing your new aid.
In addition, researchers are investigating the use of computer-aided technology to design and manufacture better hearing aids. Researchers also are seeking ways to improve sound transmission and to reduce noise interference, feedback, and the occlusion effect. Additional studies focus on the best ways to select and fit hearing aids in children and other groups whose hearing ability is hard to test.
Another promising research focus is to use lessons learned from animal models to design better microphones for hearing aids. Scientists are studying the tiny fly Ormia ochracea because its ear structure allows the fly to determine the source of a sound easily. Scientists are using the fly’s ear structure as a model for designing miniature directional microphones for hearing aids.
These microphones amplify the sound coming from a particular direction (usually the direction a person is facing), but not the sounds that arrive from other directions. Directional microphones hold great promise for making it easier for people to hear a single conversation, even when surrounded by other noises and voices.