We've all been there.... you're sitting on the couch and the damn dog jumps up and starts barking at the door or window even though you didn't hear anything, they did. Just like in narcotics, explosives, search and rescue and other detection jobs where they use their nose, dogs use their sense of hearing to do their jobs. And just like their sense of smell, their sense of hearing is much deeper and broader than their human handlers.
If it comes as a surprise to you that guns and helicopters are loud you might be in the wrong place. How loud? Normal speech is in the 60-65dB range and pain and damage occur at 140 dB. In canines, damage can occur as low 120 dB with prolonged exposure. Modern firearm manufacturers have done things to increase accuracy, reliability and precision. Muzzle brakes and porting are 2 of these things that may increase those attributes but also increase the decibel output. It's not uncommon (and usually mandatory) to have proper PPE consisting of 'ears and eyes' when you're at the range. With the advent of people adding 'pointy eared protection' to their home defense plans, more and more dogs are coming contact with loud firearms. Couple this with traditional gun dogs and LE and military dogs being exposed to guns, helicopters, and jets and you can easily see why they need PPE too....
How loud is a gun shot? Depending on caliber, and a few other factors, un-suppressed (obviously) runs anywhere form 125 dB to 175 dB+. Prolonged exposure causes damage in both dogs and people. We're often asked how do you desensitize a dog to gun fire? The very (VERY) short answer is; expose them to gun fire. You're in a catch-22 here. A Single .357 shot exposes a person (and a dog) to 165 dB for 2msec. The cumulative damage from that single 2msec shot is equivalent to 40 hours of work in a 'noisy workplace.' It doesn't take a degree in math to add that up. A helicopter runs in the 100 to 120 dB range, just a a reference. While lower in volume, the time for exposure is longer in the minutes to hours time frame.
A very close friend of ours likes to hunt. He uses a suppressed shot gun for bird hunting. He always says, "if I'm going to go def it's going to be from listening to Slayer to loud. Not guns." Fair enough. He was invited to a group hunt where there were 6 dogs used on a fence line; 3 on one side, 3 on the other. As the day wore on (and the bird count climbed) the dogs flushing with the suppressed group, according to the trainer, were having the "best hunt of their life." When they talked about it it was obvious it was because the dogs could hear.
Keeping your dogs hearing in tact is a pretty important and easy thing to do. The Mutt Muffs can help lower the dBs by as much as 50 bringing it into the safety range for prolonged exposure. The Mutt Muffs need to fit snug to be of any benefit. They make several sizes and they come in black.... like the model T