Helping Aubie this week is Dr. Martha Wilder Wilson, an associate clinical professor at AU and a licensed audiologist

Thank you, John, for your question about hearing aids. Many people with hearing loss can be helped by using hearing aids. Over 30 million Americans have some degree of hearing impairment. Hearing loss can affect anyone, regardless of age. Hearing loss is the most common disorder in newborns. The incidence of hearing loss increases as a person gets older. A person must have some ability to hear in for a hearing aid to work. Hearing aids help a person to hear soft sounds and to make conversational speech comfortably loud.

A hearing aid is an electronic device, which is basically a miniature public address system, consisting of a microphone, amplifier, receiver, and battery. However, unlike a public address system, the hearing aid is designed for a single person, the hearing aid user. Hearing aids use analog or digital processing of sound. With analog hearing aids, sound waves, such as speech or music, enter the microphone of the hearing aid, and the microphone changes the sound into an electrical signal. The electrical signal is amplified, or strengthened, in the amplifier circuit. Similar to analog aids, the microphone of a digital aid picks up sound and converts it into numbers, which are analyzed based on rules called algorithms. The response of the circuit can be adjusted by the hearing care professional, using computer software. The receiver, or loudspeaker, converts the electrical signal or the digitized numbers back into sound, and delivers the sound to the ear canal of the wearer. A battery supplies the electrical power to run the hearing aid.

There are different types, styles and sizes of hearing aids. For behind-the-ear (BTE) hearing aids, the amplified sound from the hearing aid is delivered through a plastic tube attached to a custom earpiece. In-the-ear (ITE) style hearing aids, which include in-the-canal (ITC) and completely-in-the-canal (CIC) styles, are custom made to fit into the individual’s ear. With in-the-ear hearing aids, the amplified sound is directed into the ear canal through a small tube within the shell of the instrument. The selection of hearing aid style is based on the individual’s age, the person’s preference and expectations, amount of hearing loss, hearing aid features, and the individual’s ability of manipulate the instrument. In most cases, two hearing aids are recommended. Babies and young children are usually fit with BTE hearing aids because as they grow and develop, the size and shape of the ears will change and they would “outgrow” an ITE hearing aid.

The first hearing aids, manufactured in the 1800s, were ear trumpets, made of animal horns or shells. An electric powered, table-top hearing aid was available in 1899. Vacuum tube hearing aids were developed in the 1920s and 1930s, but these instruments were large. With the invention of the transistor in 1948, hearing aids became smaller and affordable. In the 1950s, hearing aid users wore body style hearing aids, with the aid worn under their clothes or in a pocket, and the receiver, placed in the ear, attached by a wire. By the 1960s, behind-the-ear instruments were introduced. Improved sound quality and smaller sizes, such as in-the-ear styles, became available in the 1970s with the invention of integrated circuitry. During the twentieth century, hearing aids were powered by batteries and used analog sound processing technology, similar to a record player. A wearable digital hearing aid became available in 1984, but it was not a commercial success due to the size and cost. Around 1996, BTE and ITE digital hearing aids were introduced. Most hearing aids today use digital signal processing, with the circuitry operating like a miniature computer. Digital hearing aids detect and process sound faster than a blink of an eye. A digital hearing aid can be programmed to automatically adjust to the listening environment.

Before obtaining a hearing aid, the person should receive a thorough hearing evaluation by an audiologist, to determine if he could use hearing aids. In addition, children must be examined by a physician who specializes in ear disorders, called an otologist. The audiologist or hearing professional will help the person determine if he can benefit from the use of hearing aids, and will select an appropriate fitting based on one’s hearing ability, communication needs, home activities, and cosmetic preferences. The audiologist will assist the new hearing aid user in learning to adapt to the new sound delivered through the hearing aid.

Thanks for your question!

Aubie and Dr. Wilder Wilson