Turn your iPhone into a remote control for your dog. (Also works on iPod Touch.)
The app has five buttons for common dog commands. Each button plays a different ultrasonic tone only your dog can hear.
Combine the tones with your usual spoken commands until your dog learns to associate them. After that, your dog will respond to the tones by themselves.
Google "Ivan Pavlov" if you want to know more.
Note: Dogs can hear sounds at frequencies above 40 kHz. But for obvious reasons the iPhone and iPod Touch speaker only plays sounds up to 20 kHz. Therefore people with acute hearing may hear some faint sounds when Dog Caller is used.
© © D.K. Johnston