The Function of the Outer, Middle and Inner Ear
Humans are inherently social beings, and communication plays a critical role in our day-to-day lives.
That being said, everyone communicates in different ways, either verbally or non-verbally.
Since we communicate every single day with our family, friends and colleagues, it’s important to know that hearing is a crucial part of that communication.
We use our hearing to communicate every day without thinking twice. However, when you take a step back and look at what’s involved in hearing, you begin to realise how much of an intricate process it is.
This article will dive into that intricate process, explaining the structure of the ear and the functions of the different parts of the ear.
Structure of the Ear
The human ear is an intricate structure made up of several different parts that all need to be functioning well for hearing to occur.
We can break the structure of the ear down into three basic parts, the outer, middle and inner ear:
The Outer Ear
The outer ear is made up of the pinna or external ear (which is visible) and the ear canal.
The Middle Ear
The middle ear is made up of the tympanic membrane or eardrum, the middle ear cavity (which houses the three smallest bones in the ear) and the Eustachian tube.
The Inner Ear
The inner ear is made up of the cochlea (organ of hearing) and the peripheral vestibular system (semicircular canals, the utricle and the saccule).
Now that we know what parts of the ear is made of, let’s discover more about what each part does.
The Function of the Outer Ear
The outer ear is made up of the pinna (external ear) and the ear canal.
The pinna is the outermost part of the ear which is visible on the side of your head. Its primary role is to collect sound waves and send them to the tympanic membrane (eardrum) via the ear canal. Due to the physical characteristics of the pinna, it also amplifies the sound to some extent.
The ear canal extends from the pinna and is on average, 2.5cm in length. The ear canal is a tunnel that sends sounds collected by the pinna to the tympanic membrane or eardrum. In addition to this, it has a few other roles.
The outer part of the ear canal has many hairs, as well as glands that produce wax. The hairs provide a protective function preventing insects, dust and debris from going further down the ear canal.
The wax has properties that protect against infection and is produced naturally in the ear canal.
The Function of the Middle Ear
The middle ear comprises the tympanic membrane (eardrum), the middle ear cavity with the ossicles, and the Eustachian tube.
The eardrum is an oval-shaped membrane, about the size of a pea, that separates the outer and middle ear. It can be split into two parts, the pars tensa and pars flaccida.
The pars tensa has three layers, the outer layer of skin, the middle layer of fibrous material and the inner layer of the mucous membrane.
The pars flaccida only has two layers, the outer and inner layers. The sounds travelling down the ear canal reach the eardrum and set it in motion. The vibration of the eardrum then sets the ossicles into motion.
The malleus, incus and stapes are together known as the ossicles. The malleus is attached to the eardrum and then follow the incus and stapes, which form a chain. The vibration of the eardrum sets the ossicles into motion and movement of the stapes, which sits in the window of the cochlea. Due to the level action of the ossicles, the sound is amplified along the way.
The Eustachian tube connects the middle ear with the back of the nose and throat. It has three prominent roles, including equalising pressure, stopping reflux from entering the middle ear space and middle ear drainage.
The Function of the Inner Ear
The inner ear is made up of the cochlea (hearing organ) and the peripheral vestibular system (balance organ).
The cochlea is a spiral-shaped structure in the inner ear and has three chambers, the scala tympani, scala media and scala vestibuli. It also has two membranes, the basilar membrane and Reissner’s membrane.
Located on the basilar membrane is the organ of corti, which houses inner and outer hair cells vital to hearing. The movement of the stapes on the oval window sets the cochlear fluid into motion, which then causes the hair cells to bend. In doing so, the hair cells turn the mechanical vibrations into electrical impulses sent to the brain via the auditory nerve and perceived as sound.
The peripheral vestibular system is made up of the semicircular canals and the saccule and utricle, which are important for balance. The semicircular canals sense rotational head movement and the utricle and saccule detect horizontal and vertical acceleration.
Putting it All Together
When someone speaks, a bird chirps or someone beeps their horn; sound waves are created and travel through the air. The pinna collects these sound waves and sends them to the tympanic membrane via the ear canal. This sets the eardrum into motion, which then causes the three tiny bones in the inner ear to move.
The movement of the ossicles displaces the fluid in the cochlea, which causes the hair cells to bend. When they are bent, electrical impulses are created. The auditory nerve then sends these electrical impulses to the brain, where they are perceived as sound. This is an intricate process, and it’s no surprise that all of these parts must be working together for great hearing. Damage to any of these parts can result in hearing loss.
To Sum it Up
The human ear is complex and made up of many different parts. To simplify things, we can say that the ear is made up of three essential parts:
- The outer ear,
- The middle ear and
- The inner ear
Each part of the ear plays a specific role in hearing, which is why each part must be working well and working together for good hearing to occur.
If you notice that your hearing is not as good as it used to be, book in for a hearing test. If you’ve had a hearing test and have been told you need hearing aids, look no further than EarDeals.