My dog hears ‘alerts’ from miles away. If I listen very carefully I hear some distant bark. As a pup it became interesting to figure out her behavior. We have trains, a gun range, a military base nearby. I had to associate noise from each one with reassurances and petting. She is cool around them now. But I have learned to never to use the word ‘squirrel’ even casually unless there is a real target within range.