Good Hound's solid brass dog whistle with a leather key fob can be heard from over a mile away at 125dB+.
 
You can use a whistle to "talk" with your dog and establish a behavioral routine, just as you do with verbal commands or clicker training for "sit" and "stay" or playing fetch.
 
Please note that there are quiet dog whistles and loud dog whistles - this is a loud dog whistle.