How Hearing Works
- The outer ear collects sound waves moving through the air and directs them to the eardrum.
- The eardrum vibrates with sound.
- Sound vibrations move from the eardrum through the ossicles (bones in the middle ear) to the cochlea.
- Sound vibrations cause the fluid and tiny hair cells inside the cochlea to move.
- Hair cell movement creates neural signals, which are picked up by the auditory nerve.
- The auditory nerve sends signals to the brain, where they are interpreted as sounds and speech.
Hearing is a complex process that involves many parts of the ear working together to convert sound waves into information that the brain understands and interprets as sounds. The ear consists of three main parts as seen in the diagram: the outer ear (the external ear and the ear canal), the middle ear (the ear drum and the three very small bones that make up the ossicular chain: the malleus, incus and stapes) and the inner ear (the cochlea and auditory nerve). The sense of hearing is an intricate balance of processes requiring a series of actions and reactions to work.
Sound travels through the air in waves, which when picked up result in a series of vibrations within the ear. First, sound waves enter the outer ear and pass into the ear canal where the waves cause the eardrum to vibrate. Next, those vibrations are transmitted to the bones of the middle ear causing them to also vibrate. Finally, those vibrations pass through to the innermost part of the ear, which is the cochlea. Within the cochlea are tiny hair cells surrounded by fluid. When the fluid reacts to the vibrations transmitted from the middle ear, the tiny cells send signals to the auditory nerve, which in turn transmits information to the brain. The brain then interprets those signals into meaningful sounds, such as speech.
The cochlea is a snail shell-shaped organ. Different parts of the cochlea are responsible for responding to different frequencies of sound, with the narrow end responding to low frequencies and the wider end responding to high frequencies.
A presence of hearing loss may exist if any part of the hearing process is not functioning properly.