I wonyder sometimes if some hogs are deaf or something, they don't seem to react at all to gunfire. In the grand scheme of natural processes, a deaf hog isn't the worst genetic trait, they use scent and sight more then noise esp since there aren't really any natural predators for hogs. But then You introduce gunfire and it be lens a deadly trait to have
Your deaf comment reminded me of an Aggie joke. This Aggie scientist is working with fleas and the test went something like this. The Aggie scientist put a flea down on a piece of graph paper with distances metered on it. He slapped the table by the flea and yelled "JUMP!" The flea jumped X distance and the Aggie recorded the result. Next, he pulled off one leg and repeated the process and the flea jumped a shorter distance and the Aggie recorded the result. This pattern of declining distances continued until the Aggie got down to the last leg. He pulled off the last leg, put in flea on the start point, slapped the table and yelled "JUMP!" The flea did not move. He slapped the table and yelled "JUMP!" and the flea still did not move, so the Aggie recorded in his notes, "...and when the last leg is removed, the flea goes completely deaf."
There is no indication that whole sounders of hogs or even just several individuals are deaf. There is every indication of hunters misinterpreting behavior for ability as with the Aggie and the flea. Hogs that have not been hunted often do not understand that the loud BANGs mean there in death from a bullet, often fired from considerable distance (versus most threats in nature that require direct contact to be a threat), and so do not have any sort of direct behavior to respond to such a threat until they learn and understand it.
I have had hunters tell me that hogs are blind as the hog clearly looked at the hunter, but did not run away, therefore the hunter has assumed that the hog could not see him. Hogs actually see fairly well. In fact, they can navigate through the woods while running without running into trees they see so well and do it at NIGHT. Just because a hog may look at a hunter and not run simply means that the hog is not fearful of the hunter, hence has no reason to run.
When it comes to noise, I have found that hogs operating alone tend to be more suspicious of the sound of my approach than hogs among cattle or hogs in a sounder. It isn't that the hogs with cattle or in a sounder are deaf, but that they are more apt to assume the noise of my approach is just that of the cattle or other hogs, not some predator coming to shoot them.
I have heard the same stories about the poor eyesight and hearing on deer as well, again, simply the hunter misinterpreting behavior and expected behavior for ability.