What is it about fireworks?

[BettyBotter]

Reading and following advice about firework phobic dogs here (while poor Bettydog trembles in a little quivery nest in a cuddly on my lap.)

But can anyone explain what it is about fireworks? There must be something specific about the sound. Bettydog is more scared of far away quiet firework bangs than close up car horns, door slams, shouty people or anything else much louder or apparently scarier. She starts trembling even if the bangs are inaudible to the human ear.

Mine's the same, I don't know how he hears some of the distant bangs over the sound of radio/TV turned up extra loud. Although he doesn't tremble or seem scared, he goes into fierce barky guard dog mode. He's doing it now, they've started up again am very pissed off now.
Perhaps it's because fireworks are unpredictable or don't happen often enough to get used to them.

i am lucky that my tow dont care one jot! even the cat is unfazed. We took the to the town fireworks display last year!

Interesting question. Mine has so far been fine (only had him 3 weeks) with blaring sirens, super noisy cars, big clattery bangs from the scrapyard we pass on way to field and the trains that go by not 20 feet from our garden (aren't I making it sound lovely where I live!) but tonight hes panting and stressed and wont go out for a wee. Hate fireworks

Im panting with stress about my cream carpets