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How Do Hearing Aids Work?


Even if you are already certain that you need a hearing aid, or need to purchase one for a loved one, you may be unsure of how exactly hearing aids work. Here we break down exactly what a hearing aid is, how they work, and what different types and technologies are available to you.

Hearing aids are small electronic devices worn in or behind the ear. These devices ​make some sounds louder so that a person with hearing loss can listen, communicate, and participate more fully in daily activities. A hearing aid can help people hear more in both quiet and noisy situations.

Hearing aids have three basic parts: a microphone, amplifier, and speaker. The hearing aid receives sound through a microphone, which converts the sound waves to electrical signals and sends them to an amplifier. The amplifier increases the power of the signals and then sends them to the ear through a speaker.

Many people who find themselves in need of a hearing aid are suffering from hearing loss resulting from damage to the hair cells, small sensory cells in the inner ear. Called sensorineural hearing loss, this damage can occur as a result of disease, aging, or injury from noise or certain medicines. For these people, hearing aids work by magnifying sound vibrations entering the ear where surviving hair cells detect the larger vibrations and convert them into neural signals that are passed along to the brain.

There are two different types of electronics hearing devices: analog and digital. These differ in the way they convert sound waves. ​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 audiologist. Analog/programmable hearing aids have more than one program or setting. An audiologist can program the aid using a computer, and you 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 work differently, by converting 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 an audiologist 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.

Hearing aids are designed for three different ways of wearing the device: behind-the-ear (BTE), inside-the-ear (ITE), and canal. Behind-the-ear (BTE) devices consist of a hard plastic case encasing the electronic parts worn behind the ear and connected to a plastic earmold that fits inside the outer ear. Sound travels from the hearing aid through the earmold and into the ear. BTE aids are used by people of all ages for mild to profound hearing loss.

Inside-the-ear (ITE) hearing aids also consist of a hard plastic case holding the electronic components, but it fits completely inside the outer ear. Some ITE aids may have a telecoil, a small magnetic coil that allows users to receive sound through the circuitry of the hearing aid, rather than through its microphone. Telecoils make it easier to hear conversations over the telephone, or to hear special sound systems, called induction loop systems,that are found in many churches, schools, airports, and auditoriums. ITE aids are used for mild to severe hearing loss and are usually not worn by young children because the casings need to be replaced often as the ear grows.

Lastly, canal aids fit into the ear canal and are available in two styles. The in-the-canal (ITC) hearing aid is made to fit the size and shape of a person’s ear canal. A completely-in-canal (CIC) hearing aid is nearly hidden in the ear canal. Both types are used for mild to moderately severe hearing loss. Because they are small, canal aids may be difficult for a person to adjust and remove. In addition, canal aids have less space available for batteries and additional devices, such as a telecoil. They usually are not recommended for young children or for people with severe to profound hearing loss because their reduced size limits their power and volume.

The first step to finding the right hearing aid device for you or your loved one is to consult with a hearing health professional. Your ​hearing care professional will work with you to find the hearing device that best fits your lifestyle, budget and degree of hearing loss. By examining your unique requirements, you and your hearing care professional can determine the best fit for your needs.