Is there some kind of disorder where the kid can react like this? Or is it just because of the overexcitabilitlies that come along with giftedness?
Warning, totally inexpert opinion here. But I would say yes, and yes. Likely explainable by over-excitabilitites, but if it is severe enough to get in the way of everyday learning or living, there are various possible disorders which may be relevant.
I've seen quite a few posts on this forum describing extreme noise sensitivities, and my DD has a few of her own. Those turbo hand dryers in public washrooms seem to be an especially common trigger, as do buzzing classroom lights. So for lots of people, I think noise is just one of those gifted sensitivities, like shirt tags, that we become better able to control as we become older and can choose our environments a little more. The fact that your DS is incorporating the noise into a movie in his head, rather than complaining it causes him pain or misery, would make me suspect a possible boredom issue, though...
For extreme sensitivities, I've read a lot of people describing a struggle to find the line between over-excitabilities and Sensory Processing Disorder; it seems more about how much impact it is having on the person's daily functioning, I think? Noise sensitivity can be also found with auditory processing disorders (APD), and background noise can make it really hard for someone with APD to understand what people are saying to them. In my DDs case, her noise sensitivity is probably exacerbated by (or perhaps causality runs the other way - or both?) with her ADHD-Inattentive: staying focused is hard, and any distraction unhelpful. And while while she came up OK for APD, she does have some marginal scores that make extra noise extra difficult, so the two issues feed each other.
Similarly - though here I am on even shakier ground - I can readily imagine how a very bright, busy brain could easily be distracted by visual overload, especially if the text content is not extremely demanding, so there is lots of brainpower left to wander on to everything else around.
In our case, DD was found to have visual processing issues, and we can (now!) see her eyes jumping around when she tries to move them in a straight line. She also can't hold hold her eyes still, i.e. stay focused on an object after she has looked towards it. Snippets of research also suggest dyslexics as a group may have more trouble keeping the eyes moving consistently and evenly across rows of text and then onto the start of the next row (they may jump around, miss and/ or repeat words and lines, etc.). We're totally new to the visual processing issue, but I would speculate that between the ADHD, dyslexia and visual issues, DD has huge difficulty keeping her eyes where they belong in a smooth, consistent flow through the text, and anything luring them away can't be helpful.
