Why is it that some dogs are terrified of loud bangs such as fireworks ? Ours goes doo-lally whenever sahe hears anything louder than a rasping trouser trumpet !
Although dogs hearing and sense of smell is far more developed than humans, some animals maybe more jittery than others or much like humans their hearing differs from one animal to the next.
My dog(no longer with us) had on many an occasion while in the garden on a clear blue summer's day looked up and started barking. I could see nothing in the sky until I really concentrated my long distance sight and saw an aeroplane so far up, it was just a dot.
That got me puzzled,either her hearing was exceptional or her eyesight or both.
Don't you ever jump at a loud noise? Sorry if that sounds a bit abrupt, but most people who don't expect sudden noises would probably jump at one. You can't explain to a dog that there are workmen outside with big drills/children with a football/a noisy boiler etc.
My Collie leapt about a foot in the air this morning on the way home from the park because a lorry in the distance bounced loudly over a bump in the road!
And luna-tic is right, their hearing is very advanced compared to ours, so a whisper to us might be much louder to them.
Some dogs' hearing is much more sound sensitive than others. I had a male GSD, not scared of anything or anybody, apart from a sound like a christmas cracker snapping, or someone flapping a newspaper. He just went into a quivering heap and had to be persuaded there was nothing going to happen to him. I am sure it was something to do with his hearing, as any other loud noises were not a problem.