To start with, you need to keep in mind that no matter what someone says, or what their opinion of it is, what you are doing is not wrong. You do not need a reason beyond "because I can". That being said, saying "because I can" (especially to a LEO) may not be the most diplomatic way of going about business. I would suggest going ahead and telling someone who asks "I have a hearing disability that I believe affects my safety, so I decided to arm myself". I bet you'll be surprised at just how well that works.