There are three main sections of the ear which work together to pass sound from external sources through your ear to your brain for information processing. The three sections are known as; the inner ear, the middle ear, the outer ear. The inner ear is made up of the cochlea, auditory nerve and the vestibular organ for balance. The middle ear consists of the middle ear bones called the ossicles (malleus, incus, stapes). The outer ear includes the pinna and the ear canal. Information around hearing and balance is relayed from the inner ear to the brain via the auditory nerve and vestibular nerve.
The outer ear is the first place sound enters the ear, starting with the pinna which directs the sound waves into the ear canal. The ear canal is a narrow passageway which leads to the eardrum. Sound travels in waves through the ear canal to the eardrum.
The ear canal is lined with hairs and glands that secrete wax. This part of the ear provides protection and channels sound. The auricle or pinna is the most visible part of the outer ear and what most people are referring to when they use the word “ear.”
The middle ear is an air-filled cavity that turns sound waves into vibrations and delivers them to the inner ear. The middle ear is separated from the outer ear by the tympanic membrane otherwise known as the eardrum. The eardrum is a thin piece of tissue stretched tight across the ear canal, so when sounds hit the eardrum, it moves and transfers the sounds deeper into your ear via a series of tiny bones called the malleus, incus, and stapes.
The middle ear is 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 pressure on both sides of the eardrum and prevent the membrane from being damaged.
When you get some cold and flu symptoms, the Eustachian tube can become blocked with mucus, causing a build-up of pressure and temporary hearing impairment or loss as a result.
The inner ear has both hearing and balance organs. The hearing part of the inner ear is called the cochlea, which contains over 15,000 tiny hair cells. When stimulated, these hairs cells trigger electrical nerve impulses that are sent to the brain via the auditory nerve. From here, the brain then deciphers those impulses as recognisable sounds.
The ossicles are the tiny chain of three bones; the malleus, incus and stapes, which vibrate and move in the middle ear as they react to the movement of the eardrum. Through these vibrations (imagine the skin on a drum vibrating when you strike it), the ossicles transfer sound deeper into your ear for continued processing.
The eustachian tube is a canal that connects the middle ear to the nasopharynx, which consists of the upper throat and the back of the nasal cavity. It controls the pressure within the middle ear, making it equal with the air pressure outside the body.
When you get a cold or flu, the Eustachian tube can become blocked with mucus, causing a build-up of pressure and temporary hearing loss or impairment as a result.
The vestibular system works as an inner ear balance mechanism in tandem with the visual system (eyes and parts of the brain that work together to let us ‘see’) to stop objects blurring when the head moves. It also helps us maintain awareness of positioning when walking, running or riding in a vehicle. Using this feedback, the brain sends messages to instruct muscles to move and make the adjustments to body position that will maintain balance and coordination.
The ear canal functions as an entryway for sound waves, which travel down toward the eardrum. When sounds arrive at the middle ear, they are transmitted to the ossicles, which consist of the stapes, the incus, and the malleus. Sounds are then transmitted from the malleus to the cochlea of the inner ear.
After sound leaves the ossicles it is transferred into the cochlea, a fluid-filled snail-like structure that contains the organ of Corti.
The organ of Corti, otherwise known as the organ for hearing consists of tiny hair cells that line the cochlea. These cells translate vibrations into electrical impulses that are carried to the brain by sensory nerves. The different parts of the auditory pathway along with these hair cells work to give us the ability to hear sound.