In addition to barrel length, other factors come into play. Small caliber over-bore rifles bark worse than larger bores with a similar powder charge. Compare for example a .22-250 and a .308 with similar barrel lengths, the .22-250 has a sharper bark . . . a big dog bark vs a small dog bark sort of thing, the small dog is always more obnoxious. As bore size increases, the sharpness of the report diminishes as soprano gives way to baritone. I liked the sound of my 20" .375 Ultra, and frankly there is little difference between the 20" and a 22" barrel with this cartridge, but I seriously object to the sound of a 20" .243 with half the powder charge. So while decibels gives an index of volume, it doesn't tell the whole story.
Another issue that affects rifle shooters with respect to the sound of muzzle blast is the wind direction. Muzzle blast is less tolerable if the wind is in your face when you shoot, yet if the wind comes from behind you, you are less troubled by it. Muzzle brakes are not a problem in of themselves, but if you are forced to make an unexpected snap shot with a braked rifle, the cost will be high, and the greater the bore capacity, the higher the cost will be. I once fired a braked .375 H&H, without thinking about hearing protection, since squirrel guns like that don't need brakes, and the experience was indeed both unpleasant and memorable. One round from the braked 24" H&H was worth 100 rounds of .375 Ultra from a 20" tube, even if shooting into the wind. IMHO a brake has no place on a big game rifle, and if you can't handle the bump on the shoulder, an assault on your hearing is no resolution to the problem. In fact, the affects of exposure to muzzle blast contributes more to flinching than is recoil ever could, with the possible exception of extreme examples.
The current trend toward very light hunting rifles, has also driven a trend towards very short barrels. I personally don't think that rifles with barrels that are shorter than 20" is a step in the right direction, yet we see several manufacturers producing carbines with 16" barrels. I have one rifle with a 14.5" barrel, so this is clearly an example of do as I say, not as I do, but seriously, other than a specialized niche rifle, the disadvantages of very short barrels out weighs their advantage. In fact, a rifle that wears a barrel with a pencil thin contour, needs that barrel to be longer if the rifle is to balance. A butt heavy 16" carbine bolt gun is not as quick to bring to target as a 24" Weatherby Ultralight, so the disadvantages of very short barrels go beyond damage to your hearing.
Your hearing is valuable and not to be taken for granted, or abused beyond reason. Few big game hunters are willing to wear hearing protection while hunting, but only a fool engages in shooting multiple rounds when target shooting, plinking, or varmint hunting without protecting his hearing, and insisting that others present do likewise.
