[Maximo]

I am sorry that you are facing this challenge. If possible, I would buy a recording device to study your pups' activities and barking habits when you are gone. You could do this with an relatively inexpensive security camera and VCR.

I would also try talking to your neighbors to let them know that you are concerned and want to work out any problems. Some people cannot be reasoned with, so I understand if this is not a possibility.

Do your pups like TV or radio? You could add that to the fan. Are they able to see out the window? Maybe blocking their view would help.