Do you have a webcam? If so, perhaps you could try that free website that allows you to monitor your pets while you are away. This way you could actually see what he is doing and if the barking is as bad as your neighbor says.
www.mypetcams.com
Use My PetCam to watch your pet, from anywhere, for FREE!
Someone posted on YT a couple of days ago about this website....they said it was wonderful!!!