Now this method has always worked for me over the years. I found that if you fill a water squirter bottle with tepid water..(the sort you spray plants with) as soon as they start to bark..squirt them with it..The shock of the water is generally not liked and I found it worked for me. Also I found if I left the bottle where it could be seen..it said to them..''hey if we bark again..we know what will happen''' I found this method good really and not too cruel.
I do know about consistent barking..our last yorkie..sadly no more became very poorly for most of the early part of this year. and one of his problems was that he consistently barked at everything..but thats another story really.!
Still give it a try..it can't hurt can it..