I suggested collars - the noise/scent kind. I don't believe in using electric shock collars at all, but the noise and scent one I consider humane.
I wouldn't say they are a first resort but they do work in combination with other methods. If used with some thought, the dogs won't associate the unpleasant noise/small with the collar but with the act of barking. In my particular case three weeks use enabled me to stop my dog barking at people walking past our section. This was the difference between keeping and losing my dog.
You shouldn't need your dog to make noise to know they are becoming uncomfortable. Dogs communicate dis-comfort or anxiety in many silent ways - ears, mouth, tail, posture, hair along the spine (hackles), breathing. Noise may be the dogs second to last resort, and we know what the last resort is.
I loathe bark collars. They punish a dog for doing what comes naturally, for good reasons, and can make dogs fearful of barking. Some dogs work out that the collar is to blame and get panicked at the sight of collars. Others, like my Dad's dog, don't bark when the collar is on and go nuts with noise as soon as it's off. Teaching a pup that quiet is good and unnecessary barking is frowned upon is all that's needed. If a dog keeps barking then its up to the humans to work out why.
Dogs should never be discouraged from appropriate barking. A normally quiet German Shepherd two doors down set up a real ruckus one evening. The tone of the bark and it being unusual alerted us to something being wrong and we called the police. It turned out there was a very serious domestic violence incident with a woman critically injured. That dog probably saved her life.