What is otosclerosis?
As sound hits your eardrum, it vibrates, causing the ossicles to move. The sound is then transmitted through to your inner ear.
The chain of ossicles must be able to move freely for you to have normal hearing. The last bone in the chain is called the stapes.
Otosclerosis causes new bone to grow over the stapes. This leads to a reduction in movement and eventually the bone becomes fixed. This reduces the transfer of sound to your inner ear and causes hearing loss.