You'd probably have to ask a doctor. I don't really worry about my hearing too much and I have amazons, cockatoos and a macaw. The macaw is the one that is loud most often. I don't let my noisiest birds on my shoulder very often so having one scream in my ear full volume doesn't happen often. Once in a while one will time it right just when I'm walking past the cage or the amazon decides to do a high pitch sound in my ear while on my shoulder. If she keeps it up, I just put her down and don't worry about it. All my birds throwing a screaming fit at the same time is rare and usually only happens for a few minutes around feeding time if at all. If your birds are so loud you have to worry about your hearing, then you either have a whole bunch of birds or you need to work on your management practices. My breeding pairs are quite noisy in a spare bedroom and if I stayed in there very long I'd have hearing loss. But I have excited amazons and quakers doing territorial get out now screaming every time I go in there. With wood floors so it echos nicely. If I spent hours in there at a time often, it could probably damage my hearing. My pet birds that live in the living room and kitchen will make noise but its not an endless cacophony. I would not let concern for hearing loss prevent me from getting a single macaw. However, getting multiple macaws might be more likely to cause you problems. They can really get each other going with flock calling and that can be hard to get away from.
