Table of Contents
Have You Ever Wondered How You Hear?
Like most people, you probably take your hearing for granted. But have you ever wondered how you hear or how your auditory system captures, transmits and deciphers sound? Your auditory system is one of the most complex and delicate sensory systems in your body. Watch the video below to learn more.
The 4 Parts of Your Hearing System
There are four parts to your auditory system. The outer ear (the visible part extending to your ear canal), the middle ear (where the canal meets your eardrum), the inner ear (containing your cochlear) and your brain where you interpret sound.
1. Outer Ear
Sound waves are captured by the shape of your ear and are then transmitted to the eardrum via the ear canal.
2. Middle Ear
Three tiny bones and the eardrum make up the middle ear. Sound waves cause the eardrum to vibrate. The three bones or ossicles called the malleus, incus, and stapes, pass the vibration on to the inner ear.
3. Inner Ear
Vibrations from the stapes move through the fluid-filled cochlea—fluid movement stimulates sensory hair cells, which send electrical impulses to your brain.
Your brain, specifically the central auditory nervous system, is responsible for recognising and decoding electrical impulses from the cochlea via the auditory nerve, including what the sound is and where it is coming from.
How Sound Is Transmitted to Your Brain
The external, middle, and inner ear are all involved in transmitting sound to your brain.
The external ear consists of the auricle (pinna) and the ear canal. The outer ear canal ends at the eardrum membrane (tympanic membrane), separating the external ear from the air-filled middle ear.
The middle ear is ventilated by the Eustachian tube, connecting the nasopharynx (the upper part of the throat connecting the nose and mouth).
Refer to the diagram above of the auditory pathway for the five stages of sound transmission to your brain.
- Auditory pressure waves collected by the auricle pass through the external ear canal and cause vibrations of the drum membrane.
- These vibrations are transmitted to the middle ear bones, i.e., hammer (malleus), anvil (incus), and stirrup (stapes). The inner ear contains a coiled, fluid-filled tube that is named the cochlea. The cochlea is where the sound vibrations are transformed into neural form. The organ of Corti in the cochlear duct contains hair cells that turn the vibrations into electric neural signals.
- The hair cells stimulate the auditory nerve (for hearing), which combines with the vestibular nerve (for balance), forming the vestibulocochlear nerve.
- The vestibulocochlear nerve (known as the eighth cranial nerve) transmits sound and equilibrium (balance) information from the inner ear to your brain.
- The auditory cortex processes and interprets sound.