Otosclerosis is the abnormal growth of bone of the middle ear. This bone prevents structures within the ear from working properly and causes hearing loss.
For some people with otosclerosis, the hearing loss may become severe.
How do we hear?
Hearing is a series of events in which the ear converts sound waves into electrical signals and causes nerve impulses to be sent to the brain where they are interpreted as sound.
The ear has three main parts: the outer, middle, and inner ear. Sound waves enter through the outer ear and reach the middle ear, where they cause the ear drum to vibrate. The vibrations are transmitted through three tiny bones in the middle ear called the ossicles. These three bones are named the malleus, incus, and stapes (and are also known as the hammer, anvil, and stirrup). The ear drum and ossicles carry the vibrations to the inner ear. The stirrup transmits the vibrations through the oval window and into the fluid that fills the inner ear.
The vibrations move through fluid in the snail-shaped hearing part of the inner ear (cochlea) that contains the hair cells. The fluid in the cochlea moves the top of the hair cells, which initiates the changes that lead to the production of the nerve impulses. These nerve impulses are carried to the brain, where they are interpreted as sound. Different sounds stimulate different parts of the inner ear, allowing the brain to distinguish among various sounds, for example, different vowel and consonant sounds.
Image Source: NIH