Hi, I'm not so sure "It could be beneficial to the animal" is a a very good justification, and I would be wary of using it.
The main reason dogs bark incessantly is because they are unhappy. The most common reason, particularly with big dogs that are problem barkers, is because they are not payed enough attention and/or not given enough excersise.
I have researched problem dogs a lot, for the same reason most do - I have not just one next door, but I live in a poor neighborhood of small houses and yards and many people insist on having either one big dog or many medium size ones as "Guard Dogs".
Of course the problem is lack of consideration or education of dog owners - a dog that barks too much is about as much use as a dog that barks too little. The dog that cried "Wolf!" if you like.
The other thing is, big dogs need not just exercise, but also interaction - the need their brains and reactions exercised as much as anything.
So the dog that is just left in a yard and a house is an unhappy dog. Great example is my next door neighbor - I knocked a few times to politely ask that they stop their Alsatian jump at our wall and bark like crazy every time I go in the yard... only to be told "It's a guard dog, it can't be trained.".
Which of course is not a smart thing to say... what defines a guard dog? I believe it's the dogs training.
But anyway, I digress. This project seems to be a last resort - their is always going to be risk using such a device.
Talking to neighbors should always be the first port of call, although it rarely brings a response. However having tried can be useful further down the line.
Second port of call is local Animal Control. The effect of calling Animal Control varies locality to locality. Where we are, three complaints and three logs from different neighbors will have a dog removed. After the first call, they send someone to the dogs residence. If it carries on it's time to call on the neighbors, who nine times out of ten it seems are either too chicken to get involved or simply aren't as bothered as the person directly next to the offending residence.
If animal control are no use, call the local (Not 911 of course!) police at the weekend when animal control are out of hours... if you catch someone manning the phones with some sympathy you could get a result. Not likely, but worth a go. We scored lucky there and it (seems so far) to have had an affect.
After that though, it seems you are on your own. If you look at local city or town laws you will find you are actually protected. People have gone to a civil court before and had results, of course be prepared for an unreasonable neighbor to hate your guts. Animal control and police are anonymous, civil court is not.
Frankly, at this point myself and my wife have exhausted all avenues, and we pretty much know it will start again next door. I am limited on technical knowledge but I will be watching this project, I have found this is a huge worldwide problem as well as one I suffer from. I applaud Steve for stepping up and looking at it, there is no real last ditch solution as of yet.
Also, people have pointed out something like this could have ethical issues if not used for it's intended purpose by the creator(s).
Well, so is a kitchen knife if you stab someone (Like your socially ignorant next door neighbor who won't train their dog and have some respect for other peoples peace and quiet). Science and technology is full of examples, from handguns to computers to cars to TNT.
If anything, this could save a lot of work for paramedics and police - neighbors coming to blows or worse is a huge suck on their time and attention.
My rather long winded point is I think, that it should be noted something like this should be a last resort after using the law machine has been exhausted and hits a brick wall. Everyone has the right to be in their home or walk down the street undisturbed by other peoples ignorance.