[YorkieMother]

I am not a fan of using interruptors on a dog as the only way to train.
I work shh and bark on cue first.
I also work out the separation anxiety protocol first then the collar.
Separation anxiety is what you are dealing with and the bark collar may make the bark stop but not the amxiety of being left behind.
You stop the bark without dealing with the anxiety you may have a dog peel you floors up. pee in the house or lick itself until it bleeds.

But that said I have no problem with the sound collar for short term use as you train dealing with being left behind or when traveling.

Just make sure you watch your dog and make sure that they do not have a fear response to it if they do have a fear response do not use it.
If one specialist as in a board cerified behaviour person did not work find another and somethimes when it does not work it not the protocal it folowing it or needs a shift to fit the dog.

JL