When the thin membrane that separates the ear canal and the middle ear (the “eardrum”) is pierced or becomes ruptured, there will be decreased hearing and possibly a liquid discharge. A “perforated eardrum” may result from a sudden loud noise (explosion), injury, infection, or chronic Eustachian tube disorders. While most perforated eardrums caused by trauma or an acute ear infection heal on their own within weeks, some may take several months to heal. In the meantime, ears must be protected from water and trauma.
P.S. It is the size of an eardrum perforation that usually determines the level of hearing loss.