What can i do about my dogs?

i have two boston terriers one the mother and her son both r fixed ,but they yap all the time wen they in are fenced back yard and inside, i asked a vet awhile back and he said there's a collar that sprays smell r something like that to shut up there yapping?i have this device that u push a button and hurts there ears ,but i don't want to use that ,,,someone gave it to me to try and i put it next to my ear and it hurts your ears so i cant do that to my puppies, any suggestions?