How hearing works
Ever wondered how you actually hear sound? Let’s explore one of our most interesting senses.
Medically reviewed by
Updated:
May 13, 2024
A blurry image of trees
The 3 key takeaways
- Sound is a vibration that travels through the air – It’s then picked up by the ear and travels through the various parts of the organ so you can hear the world around you.
- The ear consists of three parts: outer, middle, and inner — Each work together to produce what we hear as sound.
- Auditory processing occurs in the brain – It takes place within the brain’s temporal lobe, helping us filter background noise and effectively communicate.
Hearing is a complex sense that many in the world take for granted. It is, after all, an essential part of our ability to communicate and feel connected to the world around us.
But the mechanics of hearing are a lot more complicated than you might think, and understanding hearing is crucial as you navigate the complexities of hearing loss and hearing health.
Let’s learn how hearing works.
While you may think you understand what sound is, it’s important to know how sound works and how our minds process it. Sound is actually the sensation of hearing.
Each sound is made up of waves of vibrating particles that travel through matter, typically gas (or air). For sounds to eventually reach the brain, they must first reach the ear.
The ear consists of three parts, which work together for hearing to occur: the outer ear, the middle ear, and the inner ear.
Parts of the ear
The ear is a small organ with a mighty job. Its various parts are important in how sound begins at its source and eventually reaches our brains, where sound is perceived.
The ear actually consists of three parts:
- The outer ear. Mainly responsible for capturing vibrations and funneling them down to the middle ear.
- The middle ear. Responsible for amplifying the vibrations and carrying them to the inner ear.
- The inner ear. Helps to convert the sound waves into electrical impulses.
Let’s take a closer look at how each part of the ear functions.
Outer ear
The outer ear consists of three parts: the pinna, or the part that is easy to visualize on the side of the head, the ear canal, and the eardrum. The curves of the pinna collect sound and help with localization.
The pinna funnels sound down a narrow channel called the ear canal, where it eventually meets the eardrum.
The eardrum, also called the tympanic membrane, is a small, thin membrane that forms a barrier between the outer and middle ear.
When sound waves vibrate the tympanic membrane, this also vibrates the middle ear.
Middle ear
The middle ear consists of the ossicles and the eustachian tube. The ossicles are the three smallest bones in the body: the malleus, the incus, and the stapes.
When the ossicles are set in motion by vibrations from the tympanic membrane, they amplify the sound waves, transmitting them through part of the inner ear. Although the eustachian tube does not play an active role in transmitting sound, it helps equalize pressure in the ear.
If the eustachian tube is not functioning properly, it can lead to a build up of fluid in the middle ear space, ear infections, and pain or discomfort.
Inner ear
The end of the ossicular chain, the stapes, moves sound waves through part of the inner ear called the oval window. The oval window is a membrane located at the end of the middle ear and at the entrance of the inner ear.
The inner ear, called the cochlea, is a snail-shell-shaped organ filled with fluid and tiny hair cells. When the sound waves enter the inner ear and move the fluid, this moves the hair cells.
The hair cells then convert the sound waves into electrical impulses. Nerve cells called neurons carry electrical activity to the brain through the eighth cranial nerve.
How the brain hears
Once sound passes through the various parts of the ear, the brain has to take the information it receives and make sense of it all. The interpretation of auditory information occurs in the auditory cortexes, which are located within the temporal lobes.
The temporal lobes sit on the side of your head, extending from your temples to behind your ears. We sense speech and music and differentiate qualities such as pitch and rhythm through auditory processing.
The auditory cortex assists with our ability to filter out background noise and plays an essential role in our ability to communicate with others.
It allows us to communicate in challenging environments such as restaurants, church, or parties.
So, why am I hard of hearing?
Damage to any of the three parts of the ear can result in hearing loss. Hearing loss can occur suddenly or progress over time. A diagnostic hearing evaluation looks at all parts of the ear in order to determine the cause of the hearing loss.
An audiologist is a healthcare provider trained to identify hearing loss. In order to effectively understand your hearing loss and to appropriately treat it, you will need to schedule an appointment with an audiologist in your area.
Common causes of hearing loss
Obviously, it’s impossible to diagnose every instance of hearing loss in a single article.
However, there are a few common causes of hearing loss.
These include:
- Aging. The inner ear hair cells can break down over time and result in hearing loss, as there is less auditory activity being sent to the brain.
- Noise exposure. Loud noises, whether brief or constant, can cause physical damage to the inner ear hair cells, resulting in hearing loss.
- Middle ear fluid. Fluid in the middle ear space, which is typically filled with air, can temporarily prevent sound transmission. Untreated fluid also puts you at higher risk for permanent hearing damage.
- Impacted cerumen (or ear wax). Impacted cerumen can form a block in the ear canal that prevents sound waves from travelling down the canal and through the ear drum.
Symptoms of hearing loss
There are many symptoms of hearing loss. Symptoms often depend on how severe the hearing loss is, and they might not be as obvious in earlier stages of loss.
Not everyone experiences all symptoms of hearing loss, either.
Some of the most common symptoms of hearing loss are listed below.
- Asking people to repeat themselves. If you find yourself asking others to repeat themselves often, it may be a sign you’re not able to hear all speech sounds.
- Tinnitus. Although often referred to as ringing in the ears, tinnitus can actually be any noises in the ears that are not generated by an outside source. The presence of tinnitus is a common symptom of hearing loss and should be addressed.
- Struggling to understand when you are not facing the person talking. If you have hearing loss, you might rely on facial expressions and lip reading to help you understand better.
- Avoiding social activities. Hearing loss can cause people to withdraw socially, as they are not able to effectively communicate.
- Fatigue. Finding yourself tired at the end of the day or after a social interaction could suggest your brain is using more effort to process information due to hearing loss.
If you or a loved one is experiencing hearing loss, please see your medical provider and get your hearing tested.
If you are uncertain of where to find an audiologist, use our Audiologist Explorer.
Frequently asked questions
I have a hole in my eardrum. Why is my hearing muffled?
Damage to the tympanic membrane (eardrum) will cause poor transmission of sound waves from the outer to the inner ear because the membrane is not vibrating well.
The tympanic membrane will require more energy (or louder sounds) to vibrate until healed.
I was told that I might have damage to my hair cells. What does this mean?
The number of inner ear hair cells we are born with is finite. When hair cells are damaged, whether from overuse, certain medications, loud noise, or infections, they break and eventually die off.
Hearing loss occurs when there is enough damage to cause a loss in electrical activity.
How small are the ossicles?
Human ossicles range in size from about 2mm-8mm. The stapes is the smallest, and the malleus is the largest.
The entire chain can fit on a penny!
Do I stop hearing when I sleep?
Nope! Our ears are constantly collecting sounds and sending them to the brain. Our brain, however, limits sounds processed while we sleep. What your brain allows you to hear depends on the stage of sleep.
Can damage to the ears be fixed?
Whether or not damage to the ears can be fixed depends on where the damage occurred and the type of damage sustained. Some types of physical damage to the outer and middle ear can be helped with medical intervention, however damage to the inner ear is typically irreversible or difficult to treat. Learn more about hearing loss treatments.
