It's funny how we have our own private meanings of specific words. You may want to check a dictionary on the word "appear" as it doesn't necessarily demand visual.
As to the person making the complaint, I was recently at Ft. Macon for the firing of three 30-Pounders, each with a five-pound powder charge per firing. I expected them to be loud and produce a strong concussion. I wasn't disappointed. I know the guys of Andrew's Battery who fired the middle gun, and none of them have complained of hearing loss from those firings.
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