The ear is the organ of hearing and balance, making it an essential part of how we navigate the world. Despite the importance of this organ, most people don’t know how hearing works. So what is hearing? Learn more about how the ear works.
Parts of the Ear
To understand how the ear works, we must first know what makes up the auditory system. The ear has four main parts: the outer ear, the eardrum, the middle ear, and the inner ear. Let’s look at each of these in more detail.
The Outer Ear
The outer ear contains the auricle, or pinna, and the external auditory canal. The auricle is the part of the ear that’s on the outside, and it has three parts: the tragus, helix, and lobule.
The external auditory canal is a tube running to the middle ear, and it’s the same in all mammals. Cartilage makes up the outer third of this canal, and bone makes up the rest. The tiny hairs and the modified sweat glands that produce ear wax help keep insects out of the canal.
The eardrum, also called the tympanic membrane, separates the middle ear from the outer ear. The eardrum is a transparent gray membrane about the size of a dime, and it doesn’t change as you get older. The same size eardrum you had as a baby is present in your body right now.
Attached to the center of the eardrum is the middle ear bone, called the malleus.
The Middle Ear
The middle ear (the tympanic cavity) is the space inside the eardrum. The three smallest bones in your body are in the middle ear:
- The malleus
- The incus
- The stapes
These small bones are also called the hammer, anvil, and stirrup. The three bones together are referred to as the middle ear ossicles.
The malleus is the largest of the three, with one end connected to the incus and the other to the tympanic membrane. The incus connects with the stapes. A membrane called the oval window holds the base of the stapes. The oval window is one of two membranes that separate the inner ear from the middle ear.
Together, all three bones are no larger than an orange seed, and ligaments suspend them in the middle ear.
The Eustachian tube is also present in the middle ear. It is a canal that links the middle ear to the nose, helping to equalize pressure in the middle ear, so you receive sound waves. Mucus lines this canal, just like inside your nose and throat.
The Inner Ear
The inner ear consists of the cochlea, the vestibule, and the semicircular canals. The cochlea has the shape of a snail and has two chambers that a membrane divides. These chambers contain fluid that vibrates with sound, making the hairs in the membrane vibrate as well.
The vestibule contains the receptors that, along with the semicircular canals, help with balance.
The semicircular canals are at 90° angles to each other, allowing the brain to know the direction in which the head is traveling. The canals are full of fluid and have calcium crystals inside their lining.
The eighth cranial nerve, or the auditory nerve, connects the inner ear to the brain. This nerve has the responsibility of sending hearing and balance information to the brain.
How Do We Hear?
The process of hearing begins when the outer ear collects sound waves. These sound waves begin their journey down the ear canal to the eardrum. The eardrum starts vibrating, causing the middle ear bones (ossicles) to vibrate as well.
The ossicles then perform a piston action, which sends a wave in the fluid inside the inner ear and stimulates the hairs lining the membrane in the cochlea. This action sends electrical pulses to the brain using the eighth cranial nerve, and the brain translates these electrical pulses into sounds.
Understanding the Hearing Process
Any disruption to the hearing process, no matter how small, can cause hearing and balance issues.
Knowing how the ear works and what parts make up your body’s auditory mechanism makes it easier to understand when something is affecting your hearing and balance.
With a system so delicate and precise, the best thing to do if you notice hearing loss or other issues is to reach out to professionals who can help you.