My #1 Oh God I Need to Hide in My Cave and Never Come Out-ism is what I just refer to as 'The Newt Scream'. Yeah, Newt, Aliens, that noise, which is a noise plenty of kids make all the time for a variety of reasons: extremely shrill and high-pitched and generally a sign of alarm.
As humans we are evolutionarily conditioned to respond to this sound. We can't not hear it. It's in our hard wiring: "One of the younglings is in danger, bigger human, protect the youngling!" I am completely and totally unable, for whatever reason, to tune it out to the 'dull roar, maybe glance up and see if there's a child in peril' that most folks can and do if they even notice it at all.
I hear this noise, and my whole body tenses enough to painfully cramp in an instant. I involuntarily flinch and shudder; I cannot NOT flinch and shudder. I feel an ache in my head pounding away as my blood pressure spikes right through the roof that is painful enough that sometimes my eyes will tear up. Essentially, even from a long distance away or over the din of a chatty crowd, my body responds to this noise the way a normal person would respond to someone firing off an air horn right up against their ear and I can do roughly jack nor shit about it.
No, I don't hate your kid.
No, I don't think your kid did something bad for making a noise that is as involuntary as my response to your kid's noise is.
No, I don't think you're a shitty parent because your kid made a noise kids often make simply because they are kids.
I can't filter background noise and I have exceptionally sensitive hearing (both of which I was in years of therapy with an audiologist for when I was a kid myself) but even with that in mind, nothing ever made so much as a dent in this one.
ETA: tl;dr: My worst fear is probably seeing The Babadook in a theater with a good sound system turned up to high with the doors locked. I would not simply shout "fire" to escape, I would set one and hope I burn to death before the film ends.