My son, who is almost seven, is the same. I even posted on here several times, complaining that he has gone through phases of beatboxing, non-stop talking (about rube goldberg machines), and making airplane noises. Now he constantly exclaims "bang! boom!" and makes a variety of explosive noises, complete with dramatic flourishes.
Honestly, it drives me crazy. We also have an extremely chatty four year old and the two of them are both talking and making noise non-stop.
My kids' babysitter, who was my DS7's preschool teacher and knows him well, thinks it's a way of self-regulating. When I ask my son why he's booming and banging, he says that he's acting out a story in his head.
My son has also had a verbal tic over the last six months and I'm beginning to wonder if some of his noises might also be tic-related?
Like your son, mine is sensitive to sound and dislikes noisy, chaotic situations. I do, too, and find the constant talking and noise making overstimulates me.
