The Perendale originated in New Zealand from crossing the Border Cheviot with the Romney breed. They are an open-faced, medium-framed breed that produces bright, lofty, long-stapled, medium-wool fleeces. Developed as an easy-care sheep, they are both hardy and highly adapted to marginal forage-producing areas.
It depends how badly the eardrum is ruptured. Mine ruptured a couple of years ago from a bad ear infection, and it took me at least 3 weeks to get the ringing out of my ear. Depends a bit of how good you protect the ear from pressure changes; usually between 2 - 4 weeks. If you really do have an ear problem, do NOT mess 'round.
As a rule of thumb, a hole in the eardrum that heals on its own within a few weeks or months will have minimal effect on hearing. However, continual operations on the ear drum will build up scar tissue and could cause severe hearing loss due to the subsequent scar tissue making the tympanic membrane inflexible.