I have more than 1 dog, in fact, i had dogs all my life, in the city.
I live in the forest now, in Argentina, San Luis Providence and have 4 dogs, had them for quite some time now.
They bark for different reaons.
A minor alteration on someone's house close by can set off a whole new level of dog barks, because they bark when other dogs bark, they just join
the 'fight' so to speak.
Another reason why they bark is because they sense someone close by and it can be physical or non-corporeal, i had experienced both cases.
When the dog barks like a wolf, it is expressing sorrow, stress or complaining for something that he doeasn't like, probably a noise outside.
When they bark rythmically, like constant barks they are probably barking at someone who is approuching to your house, they do this when they sense
someone that they don't recognize.
But, when they bark like they have rage, that's when you should start to worry about, they do this only when there is someone deeply disturbed close
by, when they sense a bad spirit or when they sense someone who is afraid or is attempting to break into the house.
Normally, when dogs bark, it is enough to get them into the house to stop them from doing it, once you silence their surroundings, the barking stops.
WHEN they bark and groan inside the house, I am mostly sure 2 things are happening.
1- you have someone outside your house trying to get in.
2- you have a spirit inside your house and they can feel it.
I had both experiences happened to me and my family here, in fact, my dog (inside my house) groan one night, after the lights were out due to a very
high electrical storm, she was groaning like hell, she entered my dorm and start groaning and suddently she stopped ( felted a presence all that
time, i wans't able to sleep), in the exact moment she stopped, the other dog (that was outside my house) started groaning and then it proceed to
bark and run as if someone run outside my house and onto the mountains...
It was literal, as if some spirit passed through my house, my dorm and then out to the house and into the wild...
Dogs are interesting animals, but they can be sometimes a pain in the ass, the barking is really complex because generally, the most active moment for
them is the night, that's the moment when they are more aware and they tend to bark more.
If you let a dog outside at night, they will probably bark from any noise or dog barking close by, if you put them inside, they will stop.
My 2 cents.