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How our hearing works

Our ears are truly remarkable and complex things. Many people consider that the shapely flap of skin and cartilage positioned on either side of the head to be the 'ear', but this part, known as the pinna, is just one part of a complex system of interconnected parts. Understanding this system is important for identifying potential causes of hearing loss and addressing ways of correcting hearing impairment.

Here we'll take you through in detail exactly how the ear works, but you can also take a visual journey with our helpful Interactive Ear resource.

Final Ear Diagram

The outer ear

Sound travels in waves, and directing those waves into the ear is the job of the pinna. It is shaped to 'catch' sound waves and direct them into the other part of the outer ear, the ear canal. This is a short tube which takes the waves through the bone of the skull to the protected middle ear, where the process of deciphering these sound waves begins.

The middle ear

The middle ear contains the eardrum and three small bones called the auditory ossicles: these are known individually as the hammer (malleus),  anvil  (incus) and stirrup  (stapes). When sound waves reach the middle ear and hit the eardrum it begins to vibrate, like the skin on a musical drum when you strike it. These vibrations are then passed by contact to the ossicles. These bones are shaped and positioned in such a way that vibrations from the eardrum create a bigger vibration at the other end of the ossicles - therefore amplifying the sound vibrations.

The middle ear is also connected to the back of the nose and throat by the Eustachian tube. This means that when you yawn or swallow, the Eustachian tube can open to equalise the pressure on both sides the eardrum and prevent the membrane from being damaged. Unfortunately, connection to the nose and throat means that the Eustachian tube can become blocked with mucus when you get cold/flu symptoms, which can cause a build-up of pressure and temporary hearing impairment or loss as a result.

The inner ear

The amplified sound vibrations from the osssicles then reach the inner ear - and this is where the transformation occurs. Upon reaching the spiral-shaped cochlea, the vibrations pass through the fluid within it and in doing so stimulate tiny hair cells on the inner wall of the cochlea. There are over 15,000 of these hairs, and stimulating them generates electrical nerve impulses that are taken to the brain via the auditory nerve. From here, it's up to your brain to decipher those impulses as recognisable, distinct sounds.

Balance

Aside from hearing, the ears do also have another important function: balance. Within the inner ear are three ringed canals containing fluid. The Posterior, Lateral and Anterior canals operate on different planes (think of measuring a box: it has length, depth and width) and the way the fluid in these canals moves around is how the brain helps to establish balance. The continued movement of these fluids is why people feel dizzy after spinning around, before feeling back to normal once the fluid settles again. Ear infections and illnesses which reach the ear can also therefore affect balance as well as hearing.