make a loud noise or fill an old bottle with small stones to rattle, so when he barks shake or shout at him (though dont shout shut up) no would do and praise him if it makes him stop keep doing this and he will so realise that if he barks he'll hear noise and if hes quiet he'll get praise and a little treat to. hope this works.
my dalmation done the exsact same thing what i done was filled a small water pistol gun up with water and everytime he barked i squirted him a little and after a while he stoped barking hed just look at me as if he knew he would be doing wrong if he barked at the noise he heard hehe
I sometimes use a squirty water bottle, if mine bark at cats on the fence or pigeons on the roof, and now all I have to say is 'where's that spray' and they all shut up (usually!). I used to use a water pistol, but shouting 'where's that gun' made the neighbours very nervous.
Lol!! We do the same with the pup! The very mention of 'where's the spray' stops him! He is improving but sometimes forgets himself - so we just remind him every so often if the barking gets out of hand!!! Just a little squirt now and again does the trick!!! Don't mind if there is barking for a good reason but sometimes ...... ho hum!!! :o)