What exactly is otosclerosis?

Otosclerosis. Otosclerosis generally equals stiffening of the ear bones by depositing bone around the oval window / stapes (inner of the three ear bones). This stiffens the joint, leading to worsening of hearing over time. Also, bone may be deposited around the cochler (inner ear) and contribute to additional hearing loss. If you have otosclerosis, i presume this means you have seen an ent.