My son does this. When you tell him to quiet down, he's very confused, so I don't think he even notices it.
My son does. At school they have to tell him to lower his voice and in Speech the therapist was working on that. I have to admit that I think it's better to speak loudly as I think he'll get more respect that way and I was the opposite and people complain that I sound too low and I never got respect because of it and it's my natural voice.
My son screeches too. When he is excited he will talk super fast and not take a breath in between his words. By the time he gets to the end of his thought you can barley hear him because he has no breath to continue speaking.
Yes, my older son does this even when we are in the same room. He has been reprimanded for it many times over the years in school. Not only loud but fast too. I always have to tell him to slow down.