The lowest muzzle velocity for a .25 ACP I could find is about 760 fps, which is still transsonic. Just by way of comparison, a .45 is about 900 fps and the Carcano rounds that killed Kennedy were nearly 2,500 fps.
A gun makes a crack. Partly that is the muzzle velocity, partly the gas expansion of the gunpowder. I've always assumed the loudest component is the muzzle crack as air gets seriously out of the way of the bullet leaving the muzzle.
However, all firearms are really freaking loud. Even a silencer can only make a larger round sound like a smaller round like a .22, which itself has a surprisingly loud crack.
From watching movies people may think the sound of a gunshot is a lot more "throaty" than it really is. The sound is very difficult to reproduce because, at close range, you not only hear it, you can feel it. Even when you know it's coming, it can make you flinch.
One of my pet peeves is films like Terminator 2 where people are firing handguns and shotguns in a closed elevator and their total hearing loss for the rest of the movie is never addressed. They would be saying "Huh, what?" as the only dialogue for the duration.
You know how loud a .25 would be in a closed space like a bathroom without ear protection?
Shockingly loud.
I don't know about "the fog", but I can bet Jodi's ears were ringing well into her tossing the gun in the desert.
P.S. No guy would own a little .25 as a backup weapon, much less the first gun they ever bought. Useless for defense, no fun to shoot and I can't imagine a beefy kind of guy like Travis picking up a vest pocket pimp gun and saying "this just feels right in my hand".
Nonsense.
