If I have problem in otosclerosis, does it affect the eardrum?

Otosclerosis. Otosclerosis is a problem with the third ear bone called the stapes. It does not involve the ear drum ever.
Eardrums. Otosclerosis affects the bones behind the tympanic membrane and it doesn't affect the tympanic membrane. But the decrease in function of sclerotic bone behind the eardrum can lead to decrease in hearing in the affected ear. Hope this helps.