I'd ask in the pets forum here. Although I've seen on occasion that can be like walking into a lion's den (all depends on the question asked ;) Sometimes excessive barking is out of loneliness, anxiety, fear. Something is stressing the pup. Have you tried talking with your neighbor? A lot of towns have ordinances against what is perceived as 'nuisance' barking. Again, this is something the owner will ultimately have to address to be fully effective.

We found out that our dog barks when we leave and not wanting to be a problem neighbor we went out and talked to a trainer. The first suggestion didn't work but we ended up with a no-bark citrinella collar, emits a spray towards her nose which they don't like the smell and they don't like the spay. We recorded her when we went out and the last time we did this we heard no more barking. You might want to call or go to Petsmart etc, and talk to a trainer. There is a product called a bird house that is supposed to deter neighbor dogs from barking but as you said I don't know if it will work in an apartment setting. If the neighbors are not home when the dog is barking they may not be aware.

What is that gadget suppose to do to stop the neighbors dog from barking? A sound that is suppose to travel through the ceiling?

Talk to your neighbor, they might not know their dog is disturbing you. If that doesn't help talk nicely to the landlord. If that doesn't help read your lease, what does it say about noise?

i agree the owner probably doesnt know their dog is doing that, and will probably be more than willing to help you.