I've been accused of it myself. Personally, I don't think I am that loud compared to other people, however, what I think isn't important. I have learned that if you are loud, people don't listen to your words, all they hear is loud. It doesn't matter if you are angry, or upset, or excited about something, all they hear is loud and they stop listening. Some may tell you "Shh!" Others may not. You may think that this isn't a big deal and others should just deal with it. Well, they do. They just let you go on being you and they go on being them.
There is a young man in my community that I believe is on the spectrum. He hangs around the coffee shop and the fried chicken place because he has nowhere else to go and they are about the only places that will tolerate him. I have had a chance to observe how he interacts with others and how they interact with him. For example, he freely interrupts other customers while they are placing orders and they have to wait for him to finish his lengthy monologues before they can continue. The owners don't say--as they would to "normal" customers--"hold that thought a minute" or "excuse me, I have to get this person." No, he just barges in and they let him, because apparently they have learned that he is unstoppable. And they hope that the customer is understanding and won't decide to go somewhere else. Otherwise, they've lost a sale. So it's an awkward thing to have him hanging around.
A while back, he applied for a job at a pizza place. The owner did not turn him down, but he did not hire him either. He just said, "come back later." So the kid comes back, and nope, not now, later. What he doesn't realize is that there is no job and never will be a job. Why does the owner play such games? I don't know. Maybe it's because he doesn't know how to handle the situation. Maybe he is aware that if he comes right out and tells the young man why he won't hire him--why nobody will hire him--he may be opening himself up to charges of discrimination. The point I am making is this young man is tolerated but not really wanted. People feel sorry for him but not sorry enough to coach him or if they have, have found that it is a waste of effort.
So when someone tells me to modify an aspect of my behavior--even if I might not agree--I make an effort to comply. Because I've seen what happens otherwise.