I've tried everything I can think of and none of it has worked so I thought I'd ask here, Auburn's post reminded me to do it.
I taught Ben when he was young to speak on command, and then to be quiet on command...all was well and that worked for some time. A few months ago, his behaviour changed (yes he's been checked by a vet) and he now goes into a barking frenzy whenever anyone comes near the house or *gasp* knocks on the door, and it's as if he's gone deaf to me, he's so focused on what he's barking at. Around the time this change took place there was a string of burglaries in my area, which leads me to believe that someone tried to break in when I wasn't home, and while Ben warned them off he now has a hair-trigger response to this.
I've worked again on our speak/quiet commands, rewarded for silence, redirected him, tried interrupting with noise (not me yelling, various other kinds of sudden sounds like clapping, whistles etc), put him through obedience commands instead, sprayed him with water and *flame suit on* used a citronella collar as a final resort. None of it has worked.
I'm going to have a dog predisposed to guarding in my house very soon, and while I expect that guarding to take place I'd rather he didn't learn from Ben that every single noise needs to be barked at until he feels the threat is over. What has me stumped is that I DID manage to prevent this with Ben for the first 2.5 years of his life and then he changed overnight and I can't snap him out of it.
With the exception of the past few weeks because I've been injured, he gets 2 long walks a day, training sessions, kongs and other puzzle toys and plenty of attention from me, so I am fairly confident in saying this is not a boredom or excess energy problem. Right now he is only getting one long walk a day, that will change next week and all of the other things still apply.
Any ideas, anyone?
ETA: I do expect dogs to bark at odd noises or people knocking on the door. I don't expect dogs to bark when they hear someone talking across the street.