I do not employ dog whistle training, but it would work....if the dog were properly trained.
I have a vocal command "quiet" to control my dogs' barking. People in the dog world know that shelties - the breed of my three dogs - are HUGE barkers. They were actually bred to bark as they use their voices to herd livestock on the Shetland Isles. They basically annoy the livestock into moving. So these dogs LOVE to bark - usually just for fun. :)
A Sheltie breeder once said it was impossible to stop more than two Shelties from barking. Nonsense. If you properly train the cue, the dogs will not bark. It's really as simple as that. My bred to work Shelties are what a regular pet home would describe as "hyper." I searched long and hard for about as "hyper" as I could get in my shelties. The most drivey is also exceedingly stubborn.
The trick to training is simple. You reward positive behavior and without using punishments (or using only very slight ones), you NEVER let the dog get away with barking once a command has been given. There will be an extinction burst (Google it!), but the dog will learn impulse control over his barking. CONSISTENCY is the biggest key to training. You have to be 100 percent accurate in your commands and your requirement those commands are met.
If you give your dog a "quiet" command and the dog continues to bark without your intervening (without much punishment, btw), what has the dog learned? To bark, of course!!! And that its owner is a weak trainer. :)
Good dog training requires complete consistency, love, rewards, understanding of how punishment causes emotional baggage, and attention to very slight detail.
One of the best compliments given me was from a fellow dog trainer who said my training was very "black and white." In other words, I was exceedingly consistent. I knew the behavior I wanted from my dogs, and I made sure that behavior was given. With as much love and as little punishment as possible. If you make your "quiet" command black and white to the dog - no matter how long it takes - you will have success.
I may need to write some hubs on concepts behind training. :)