Are we specifically talking restaurants here? Or just in public?
I have a daughter with behavioural problems, so over the years I've been in some might difficult situations with regards to behaviour and some of that was in public.
One of the things I have realised is that they are pretty smart and often don't distinguish between positive and negative attention. So completely ignoring and not reacting, followed by minimal excitement distraction, would be the best approach in my opinion.
If every time I squealed people jumped and looked at me/spoke to me/started to jovially "distract" me by talking to me and pointing something out, I'd probably be quite liking the fact that little old me can have such a big effect on the world, and continue.
If my baby started squealing mid-meal, initially I would apologise to other diners about the phase, and say best thing is ignoring it (if I said anything), and of course if it proved to be lengthy, I would remove child from the situation, maybe go change a nappy and have a short break to try and change the tone, and return to the table. If it turned out to be a spectacular case of squealing, then I might that day admit defeat and leave the very interesting restaurant and go home and do something very bland and boring, like put baby down for a nap.
My aim would be to make the squealing as unappealing as possible, without getting into a head to head with telling off (negative attention), or distracting them (positive attention), trying to continue what I am doing because they can't learn at home what not to do in public, and if I do leave, to make it non-rewarding, so they don't think that they can use it as a way to get away from places and go do something they find more interesting.