Otology is a branch of medicine which studies normal, pathological anatomy and physiology of the ear (hearing). Otology also studies vestibular sensory systems, related structures and functions, as well as their diseases, diagnosis and treatment. Otologic surgery generally refers to surgery of the middle ear and mastoid related to chronic otitis media, such as tympanoplasty, ossiculoplasty and mastoidectomy. Otology also includes surgical treatment of conductive hearing loss, such as stapedectomy surgery for otosclerosis.