Dogs can hear sounds four times further away than we can, they can hear higher frequency sounds than us, and they are much better at differentiating sounds than we are. They are also able to move their ears (unless we've altered those ears for them!) in such a way that they can better locate where sounds are coming from. What this means for us as their caretakers is that we need to respect and acknowledge that they know way more about what's going on around them than we do.
When your dog barks, they are barking for a reason; they heard something. Now, what they heard may not be all that important to you, but letting you know they heard it, is important to them. It's actually part of their job and one of those key reasons early humans invited canids into their campsites. It's your job to let your dog know you appreciate the heads up and then let them know that was enough, no need to persist in barking. One of the benefits of doing it this way every time your dog barks is that if something bad/distressing/dangerous is happening and your dog barks, you aren't going to tell them enough/quiet. In fact, you are going to hope that they bark so loud and so long that they scare away whatever it was that triggered the barking in the first place, and if not, that their sounding of the alarm will bring assistance your way.
So, your dog is digging up your yard and you can't figure out what's the trigger? Consider that it might be burrowing animals! Dogs can hear those pesky moles, gophers, etc. digging under your yards and gardens. When they hear them, they want to catch them and often will dig several holes as the pests try to escape their intrepid canine hunters. And if you see one of those telltale mounds of dirt in your yard, that's those pests pushing up the turf to get to your garden, not your dog digging. Pick up some of that dog excrement your dog just made and put it in the holes dug by those pests. They are repelled by it and maybe your dog will stop digging there as well!
Have some fun learning just how amazing your own dog's hearing really is. Put your dog in a sit or down in the other room. Hide from them in a closet or a room behind a closed door. Quietly say their name or call them. How long does it take them to find you? Do you think they used that amazing hearing, or did they sniff you out, or both? Research shows that most dogs love this game and are delighted to play it with their owners, whose voices and requests are familiar and rewarding, and are less enthusiastic about playing it with unfamiliar people.
Another fun game for you and your dog: The next time you're on a walk and spot a park bench, go ahead and stop. Have your dog relax near you, close your eyes, and just listen. Force yourself to hone in on just what you hear. You have to focus on just the sounds and trust your dog to stay near you. Now imagine how loud that truck must be for your dog; how annoying that human talking on their cell phone; how stimulating that buzzing bee; and how scary that motorized scooter that just whizzed by. What you will take away from this exercise is an appreciation for how hearing and experiencing these everyday sounds the way your dog does must be rather overwhelming at times.
And finally, don't bother purchasing those ultrasonic rodent and insect repellents for your home. Not only does research show that they don't work, but the high frequency sounds they emit are very annoying to your dog and hard to get away from if you've got those things plugged in all over your house. Again, just because you can't hear it doesn't mean your canine companions can't.
As always, if you have questions about your pet's behavior, you know where to find me.
With ears like this, I'm pretty sure Henley hears things happening on Mars!