High frequency sound to stop dog barking?

I found a web site where you can buy a high frequency device that will hurt a dogs ears when it barks. They only work up to 50 feet. I am going to build one that will work uo to two city blocks away if I have to. In the mean time I have found a safer way to stop it. I got the phone number of party a block away and every time the dog barks (mostly)12am on) - I call ---the dog then stops barking!!!!TRY IT.