How Hearing Aids Work: An Introduction
Today’s digital hearing aids represent the marriage of cutting-edge hardware design and sophisticated software, yet their roots trace all the way back to the invention of the telephone and microphone.
The first large, bulky hearing aids circa the late 19th century barely resemble today’s tiny devices, but they still share some basic components – a microphone, amplifier, speaker (also known as a receiver), and a power source like a battery. Explaining how the technology has advanced to make hearing aids smaller and more capable, and determining whether they can help you requires an understanding of how hearing works and what causes hearing loss. So, let’s start there.
How we hear
The ear is comprised of three parts: the outer ear, the middle ear and the inner ear. The outer ear collects sound waves and funnels them to the eardrum in the middle ear, causing it to vibrate. The middle ear is an air-filled space. As the eardrum moves, it sets into motion three tiny bones called the malleus, incus and stapes that transfer the sound vibrations to the cochlea in the inner ear. The inner ear is a fluid-filled space. Fluid in the cochlea stimulates thousands and thousands of sensory cells called ‘hair cells’. Hair cells detect the pitch, or frequency of sound, and send impulses to the brain via the auditory nerve. What makes this delicate chain reaction even more remarkable is that it happens instantaneously.
A person incurs hearing loss when a problem is found at any point in the auditory system. Hearing loss ranges in degree from mild to profound deafness. 48 million people in the United States are affected by hearing loss, and it can occur at birth or can develop at any age. Approximately 3 million children in the U.S. have a hearing loss; 1.3 million of them are under the age of three. Possible causative factors to hearing loss include genetics, disease, infections, noise exposure or side-effects to certain medications.
Hearing Aid Anatomy
In simple terms, hearing aids give access to sound by magnifying vibrations and analyzing incoming information to be optimized for individual hearing losses. So, hearing aids deliver enhanced sound signals to the ear.
Any model the wearer places inside the ear canal is an In-The-Ear (ITE) model. All components of the hearing aid reside in the wearer’s ear. BTEs (Behind-The-Ear) are so named because most of the hearing aid components are worn behind the ear. BTE devices contain the speaker in the housing and have a hollow tube attached to a sound delivery system leading into the ear canal.
BTEs are durable and easy to maintain, but not as popular as their receiver-in-the-canal (RIC) counterparts. Like BTEs, RIC devices are placed behind the ear, but are smaller and less visible. The receiver rests in the ear canal instead of the device housing, connected via tiny electrical wiring.
Regardless of whether hearing instruments are placed behind the ear or in the canal, they all contain a battery, a microphone and amplifier, a receiver/loudspeaker, and an electronics package. Manufacturers are constantly incorporating new technologies to make hearing aids smaller and more effective.
For example, advancements in battery technology enables replacing disposable Zinc-Air batteries with rechargeable hearing aids based on lithium-ion (Li-Ion) technology. Li-Ion batteries are fast-charging while still maintaining a sleek, aesthetic look. In fact, some Li-Ion hearing aids can provide a full day of hearing plus wireless streaming on a single three-hour charge.
The electronics package is what distinguishes modern digital hearing aids from their larger ancestors. The most important component is the chip, which serves as the brain of the device. Hearing aid chips process sound using advanced algorithms that are now developed with machine learning.
If all that seems complicated, consider this: the entire electronics package is about the size of two grains of rice!
No matter the model and dry list of technical specs, it’s not an overstatement to call the experience hearing aids deliver “life-changing.” It becomes much easier to carry on conversations in noisy environments, like a party or loud restaurant, and hear quiet whispers while in a movie theater. You don’t have to turn the television volume up and down to alternate between listening to the show you’re watching and talking to the person sitting near you. Some of today’s models even enable you to connect wirelessly to your mobile phone, television, and other personal electronics via universal Bluetooth technology.
Stigma is a major barrier to people seeking treatment for hearing loss, so if you’re on the fence, don’t let vanity or fear prevent you from realizing the benefits hearing aids provide. After all, hearing health is associated very closely to overall well-being.
Seek out a certified Hearing Care Professional (HCP) to diagnose whether you have hearing loss and to what degree. Your HCP will advise you on whether hearing aids are the appropriate treatment plan for you. Also, based on your communication needs, the HCP will recommend the style that will be the most effective and most comfortable.
Enjoy the delight of sound!
Dr. Shannon Basham has been an audiologist for more than 16 years and is the U.S. Director of Clinical Training for Phonak. She is responsible for managing Phonak’s clinical training team including content development, implementation, and communication of training and education programs supporting Phonak products and accessories.
Shannon joined Phonak as the National Training Manager in 2010 after working for inSound Medical as a professional trainer. Prior to that, she practiced as a clinical audiologist in Georgia and Florida.
Shannon is a firm believer that hearing health is tied to overall well-being. She is a promoter of deep canal fittings including Lyric™, the world’s only extended-wear hearing aid. Shannon received her AuD from the University of Louisville in Louisville, KY.
 Hearing Link, “How the Ear Works”, 2018. https://www.hearinglink.org/your-hearing/about-hearing/how-the-ear-works/  Center for Hearing and Communication: http://chchearing.org/facts-about-hearing-loss/