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How Does Hearing Work? The Outer, Middle and Inner Ear Explained
How do we hear? Find out how the outer, middle and inner ear work together, what the ear canal does, why you have earwax and how noise damages your hearing.
Take the next step for your hearing
You hear all day long without having to do anything for it. But behind that hearing is an ingenious system. In a fraction of a second, your ear turns a vibration in the air into a signal that your brain recognises as a voice, music or a warning.
In this article you can read how hearing works, from the outer ear to the brain, what the ear canal does, why you have earwax and how noise can damage your hearing.
From sound wave to sound
Sound consists of vibrations in the air: small, rapid changes in air pressure caused by a sound source. How those waves are created and what pitch and loudness are, you can read in what is sound.
The ear picks up those vibrations and passes them on. That happens in three parts: the outer ear, the middle ear and the inner ear. Only in the brain does the vibration really become sound.
The outer ear
The outer ear consists of the pinna (the visible part of the ear), the ear canal and the eardrum. The pinna is the only part of your hearing you can see. It works like a funnel that catches sound, and its shape also helps you tell whether a sound is coming from in front of you or behind you.
Through the ear canal, the sound reaches the eardrum. In adults the ear canal is about 2.5 centimetres long and runs at a slight angle. It also has a protective job: dirt and dust are caught before they reach the eardrum, and the ear canal keeps the eardrum warm and stops it from drying out.
The eardrum is a thin, sensitive membrane that closes off the ear canal. When a sound wave arrives, the eardrum starts to vibrate with it.
The middle ear
Behind the eardrum lies the middle ear, a small space filled with air. It contains three tiny bones, the ossicles: the hammer, the anvil and the stirrup. They are the smallest bones in your body.
The eardrum passes its vibration to the hammer, which passes it via the anvil to the stirrup. Along the way, the vibration is amplified. That is necessary, because in the inner ear the vibration has to move from air to fluid, and fluid is much harder to set in motion.
From the middle ear, the Eustachian tube runs to the back of the nose and throat. This tube keeps the air pressure equal on both sides of the eardrum. That is why your ears pop when you swallow or yawn, for example on a plane. If that does not work well, you get a blocked ear or ear pain during the descent; what helps is explained in ear pain and pressure when flying.
The inner ear
The inner ear consists of the cochlea and the balance organ. The cochlea is a coiled tube filled with fluid. The stirrup pushes against a small window in the cochlea, which sets the fluid moving.
Along the inside of the cochlea are thousands of hair cells. When the fluid moves, the tiny hairs on those cells bend with it. As they do, they turn the movement into electrical signals. Each spot in the cochlea responds to its own pitch: the high tones at the start, the low tones further along the spiral.
The signals travel along the auditory nerve to the brain. There they are recognised and given meaning: a familiar voice, a melody or a car horn. Only then do you really hear something.
Try it yourself
Where in your cochlea does a tone arrive?
High tones are picked up at the start of the cochlea, low tones right in the centre. Slide and see where the tone lands.
Outside: high tones · centre: low tones
Noise damage starts here first (3,000–6,000 Hz)
4,000Hz
Whistles, birdsong and a crying baby. Noise damage often starts around 4,000 Hz.
Start with your volume low. The tone stops by itself after 30 seconds.
How high can you hear?
A tone glides from 8,000 to 20,000 Hz in 20 seconds. Press stop as soon as you can no longer hear it.
Earwax and the ear canal
In the outer part of the ear canal are glands that produce earwax. Earwax is not dirt but a protective layer. It traps dust and dirt, keeps the skin supple and slows down bacteria and fungi. The movements of your jaw when you talk and chew slowly push the earwax outwards on its own. In other words, your ear canal cleans itself.
Sometimes that goes wrong and the earwax builds up into a blockage. That often happens because of cotton buds, which actually push the earwax deeper, or from wearing earplugs a lot. Sounds then seem muffled and your ear feels full. Dutch GP guidance (Thuisarts, by the Dutch College of General Practitioners) advises lukewarm water first: spray it into your ear with the shower head once a day, or put in 5 drops twice a day, for 5 days. Ear drops from the pharmacy are not needed: water works just as well. Your own doctor can advise you on the rules and options in your country. Read more in our articles on earwax blockage and how to clean your ears.
Still blocked after 5 days? See your GP or have the earwax removed. At our locations in the Netherlands, for example, you can have earwax removed by us.
Please note
Call your GP straight away (out of hours: the out-of-hours doctor service, or 112 in an emergency) if you suddenly hear much less or nothing at all, have severe pain with fever, pus or fluid from the ear, or feel dizzy.
How noise damages your hearing
The hair cells in the cochlea are vulnerable. Sound that is too loud or lasts too long overloads them. At first you notice this as a muffled feeling or a ringing after a concert or a day in noise. That usually wears off. If it happens often, hair cells become permanently damaged. They do not grow back, so the hearing loss is permanent. Often the high tones go first.
Noise damage can also lead to tinnitus: a ringing, hissing or buzzing that isn’t really there. The risk starts at about 80 dB(A) if you are exposed to it for a long time. The pain threshold is much higher, at around 120 to 130 dB. So your hearing can be damaged long before sound starts to hurt. How long you are safe at which sound level, you can read in how many decibels is harmful, and how to prevent damage in prevent permanent hearing damage.
Hearing problems
Sound travels a long way before you hear it, and something can go wrong at every point. If the transmission in the outer or middle ear is disturbed, for example by an earwax blockage, fluid behind the eardrum or an infection, this is called conductive hearing loss. It can often be treated. If the problem lies in the inner ear or the auditory nerve, it is called sensorineural hearing loss. That is usually permanent.
Hearing loss can be present from birth, but more often develops later in life. Ageing plays a big part, as does noise. If you notice that you are hearing less well, your GP can arrange a hearing test. If you work in noise, you often have a right to a hearing test through your employer: under EU rules that applies above 85 dB(A) (Directive 2003/10/EC), and national rules can go further. We carry out such hearing tests on site at companies. If the hearing loss is permanent, a hearing aid can help you hear better again.
Protect your hearing
Noise damage is easy to prevent. Wear hearing protection when it is loud: at work, at concerts or during DIY jobs. Custom earplugs are made from an impression of your ear canal. That way they seal well and stay comfortable even after hours, while the filter brings the volume down to a safe level.
Custom earplugsProtect what you hearWe take impressions of your ears and choose the filter that suits you together. Not near one of our locations? Have impressions taken locally and send them to us. Book a free fitting
Got a question? We're all ears.
Frequently Asked Questions
Read MoreFAQ
The outer ear catches sound and channels it through the ear canal to the eardrum, which starts to vibrate. Three tiny bones in the middle ear pass that vibration on, amplified, to the cochlea in the inner ear. There, hair cells turn the vibration into nerve signals, which travel along the auditory nerve to the brain.
The ear canal carries sound from the outer ear to the eardrum. It also protects the eardrum: glands in the ear canal produce earwax, which traps dirt, dust and bacteria and moves out of the ear on its own. The ear canal also keeps the eardrum warm and stops it from drying out.
The ear is the organ of hearing, one of the five classic senses alongside sight, smell, taste and touch. The inner ear also contains the balance organ, which helps you stay upright and sense your movement and posture.
The Eustachian tube connects the middle ear to the back of the nose and throat. It keeps the air pressure equal on both sides of the eardrum. That is why your ears pop when you swallow or yawn on a plane or in the mountains.
That depends on the cause. An earwax blockage or a middle ear infection usually clears up. Damage to the hair cells in the inner ear, for example from noise or ageing, is permanent. A hearing aid can then help you hear better.
