Oddly enough, sometimes larger ANs are the ones that do not cause hearing loss, possibly because they are located mostly in the CPA instead of the IAC. When I was diagnosed I didn't have any hearing loss that I could tell. I did suffer a couple of episodes of complete hearing loss afterwards, which were resolved by steroids.
As a general rule (although really there are no rules when it comes to ANs), the better hearing you have going into treatment, the better the chances to retain some of it. This seems to be true for both radiation and surgery (the hearing preservation methods). I had GK and up to now I have preserved most of the hearing, and all word recognition (hopefully tomorrow's ENT test will confirm this). I remember quite a few others on the forum who went into GK/CK with very good hearing, and have preserved it. But it should also be noted that based on statistics hearing can diminish over the long term, even if preserved initially.
Marianna