Had a feeling I heard of that new article somewhere or maybe it was a different one about getting traumatised by a shooting videogame. What a pansy.
That said. It does pose an interesting question when guns were less advanced up to muskets when nobody had ear muffs for sound protection.
I presume gun users those days besides hunting and using it against other people will retain possible damages of using a gun that may damage their ears excluding other hazards during wartime.
Getting recoil from a musket I'm not sure of unless I search that.
Muzzle-loading firearms, which muskets are only a subcategory of, are actually quote a different beast than most modern firearms.
Firstly, they're almost ALWAYS firing a larger caliber round than modern weapons. The SMALLEST they went was about .30 caliber for black powder revolvers, and most rifles were chambered in at least .45 caliber (typically long rifles). The famous Brown Bess Musket, used by the British through the 18th century, was nearly .70 caliber.
Further, those weapons used proper Black Powder, not modern smokeless powder. They're two very different compounds, and modern powder is actually more powerful than Black Powder, while also less volatile. On top of all that, with Black Powder weapons you would consciously alter you powder load depending on what you were doing with the weapon at any given time, with the rule of thumb being that for shooting to kill you wanted to fire approximately three times the caliber in grains (IE, for a .50 caliber weapon, you'd use 150 grains of Black Powder).
All that said, Black Powder weapons do tend to be quieter than modern ones for a variety of reasons. The noise from firearms mainly comes from the explosive discharge of the powder. The more efficient and tightly contained the explosion, the louder it ends up (sound is, after all, merely a shockwave in the air, the more intense the shockwave, the louder the sound). Due to the way Black Powder firearms work, they are simply less efficient at containing the explosion than modern firearms. Thus they tend to be quieter. Not so quiet as to where one shouldn't wear hearing protection went using one, especially if you're going to be around a lot of them, but not so loud as to give you tinnitus (that's the formal name for the ringing in the ears folks are referring to) immediately.
As to the question of kickback, they actually tend to not kick as much as you'd think. Bear in mind, traditional Black Powder weapons are made of steel (for the barrel), brass (for the lock), and hardwood (for the stock)*. Neither of these things are exactly LIGHT. The Brown Bess musket mentioned earlier weights a bit over TEN POUNDS. In comparison, the original AR-15 weights just over six. This increased mass, combined with less well contained explosion means that most black powder weapons don't kick all that much when used when firing a killing load. And even less when you're firing a practice load (that is, firing as many grains as your caliber, meant for casual target shooting as to not waste powder).
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* Why yes, the parts of a musket are, in fact, what the old saying of "lock, stock, and barrel" to mean "everything" is referring to.