The wind post made me think of this.  As kids, we used to take the dog way out behind the barn and yell his name at the barn.  It would echo off the barn and away he would go on the run towards the barn.  Then we would call him back to us.  Then we would echo him to the barn again.  Poor dog, he got a lot of exercise till he caught on.  Wasn't long before he welcomed the echo luring him back to barn so he could be rid of us, 'cause after he caught on he wouldn't come back again.  LOL   Might be a geat way to exercise your pooch though, for those days when you just aren't up to joining in.  Find an echo.