Hi XXXXXXXXXXXXXXX~
Unfortunately as you are finding out, some dogs are born barkers. Factor in the fact that your dog is pretty young and is in a new environment where she might not feel completely comfortable at this point, and you have a pretty good combination of a marathon barker.
Of course, yelling at the dog to be quiet is futile, because barking dogs interpret our loud vocalizations as our attempt to join in the conversation they're having (ie: if the dog is barking at someone outside they're saying, "Come quick! Check it out! Friend or foe? What do you want me to do now? Oh, now you're yelling too, so I'd better keep barking!!"). Your yelling can unintentioally served to reinforce her yapping. You will need to re-train your new pup (and yes, I know your dog is an adult, but at just a year, she's still very young and probably has some puppy behaviors left) so that she develops new behaviors.
When the dog barks, ignore her. Patiently wait for her to stop. After a few seconds of silence, introduce a cue by saying 'hush' and then rewarding her. Timing is critical!! Do not reward her until she has been quiet for several seconds. Think like a dog for a moment: If given the options, which would you choose: keep barking or hush and get a treat?
Conduct these training sessions several times a day until your new dog figures out that 'hush' means to be quiet and that being quiet brings the treats, while barking brings nothing. Make the pauses between her silence and your 'hush' cue longer and longer. Then start saying 'hush' when she is actually barking and reward her when she stops. Remember not to keep repeating that phrase though, because it will only reinforce her to keep barking.
I also tend to use a back-up strategy: diversion. Instead of yelling at the pup when she barks, call her to you and reward her for performing a desired behavior, like sitting in front of you for a moment or fetching her favorite toy. For safety reasons, you don't want this pup to behave like a canine mime if someone should be bothering your house. It's good that she alerts you, but by trying a diversion tactic and rewarding her silence rather than her noise, you will benefit everyone by having a better behaved dog who no longer irritates your ears (or the neighbors!) with her non-stop barking.
Some people swear by bark collars (a fitted collar that has two metal prongs that fit snug up against your dog's throat and illicit a small charge of electricity whenever the dog barks), while others say that using medications that range from Valium to DAP (dog appeasing pheramone) collars. Some experts even suggest getting a second do to keep your anxiety dog company.
Personally, I'm a fan of using a DAP collar. I've had excellent experiences with them when I had to use them on my own seperation anxiety dog. Whenever I'd leave the house, my Maltipoo would urinate and defecate in his crate and would howl non-stop. Once I put the DAP collar into use, things got a lot easier on both he and I. The way the collar works is that it is impregnated with these pheramones that are similar to the ones a bitch gives off while nursing pups. They have a calming effect on the animal, and the best part is that you can find them on Ebay for a fraction of the cost of a new one at your vet clinic.
Other modifications you can do are sort of like trial runs. Put your jacket on, grab your keys and leave the house. As soon as you hear the dog start to bark, come back in and give her a stern 'NO'. Make her sit or lie down until she's calm. Repeatedly doing this for longer and longer periods can get her into the habit of remaining calm while you're out of the house.
Another thing is to give her something to distract her from the fact you're leaving. I recommend using Kongs to many of the clients at my work. They fill the Kong with treats (it's a hard plastic toy with a hole in the center to conceal the goodies) and then toss it to the dog right before they leave. The dog is so preoccupied with the Kong that they don't notice the owner leaving.
If none of these work, and medications don't work, you can always look into doggie daycare for your girl. Most cities have places where you can drop off your dog while you're away from home and they'll take care of it. They get treats, they get to play with other dogs, and some places even offer grooming. It's not the ideal answer, but it beats the alternative...at least until your neighbor moves out.
And please, please, PLEASE remember that this behavior didn't start overnight, and as such, you won't be able to break her of this habit in a day or two. Patience (and maybe a pair of ear-plugs) here is the key!
I hope this helps.
Certified Veterinary Technician
Associates Degree in Veterinary Technology. State and Nationally certified.