As Brainless has said 100% consistent ssh or out.
I have a barker and he always gets worse during holidays. We have more people walking past, there are more distractions for me so that I don't get to him fast enough, and then visitors leave doors open!
I don't think mine will ever stop barking completely (and neither should he) but I work on the principle that I'm happy for him to tell me someone is approaching or walking past BUT I don't want to be told 10 times. He can bark once or twice then I thank him and call him away to do something else - on your bed, sit, come with me - anything will do just to move him away from the window.
If I know we have a major hazard approaching (foxhounds, cows, postman) I'll either keep him with me or put him in back where he has no windows. It's a nuisance, but manageable, and all part of living with him - a dog almost perfect in every other way

BTW - yes it does have an effect on your non barker. My gundog joins in too but as it's less instinctive with him and he's just copying, he is less likely to do it when on his own and will ssh very quickly once he's told me there are weirdos (cows) walking by!!
Kindness is the language which the deaf can hear and the blind can see ~Mark Twain