Companies and researchers are always trying to find innovative ways to expand the smartphones and tablets we use everyday, whether it's a new app or some kind of hardware accessory. And now, a team of researchers from Carnegie Mellon University and Disney Research are leveraging ultrasonic audio coming from our devices in order to develop new kinds of interactive mobile controllers.

The research comes in the form of plastic add-ons known as Acoustruments. These accessories send ultrasonic sound from a smartphone's speakers and then re-route it back to its input. An internal app can then analyze the changes in the audio between the output and input to create user commands. 

The technology could be used to create any number of physical add-ons, not unlike what we see with NFC style toys. As you can see in the example video below, the researchers have a number of prototype applications for the tech including what appear to be interactive kids' toys and other flashy phone and tablet controllers/add-ons. We could also see phone cases that can tell when the device is being held, squeezed (pressed) or just resting comfortably on the table. 

There are no immediate plans for the Acoustruments, but reports suggest the very lower power the technology requires from your smartphone will likely be a draw for some manufacturers.