A growing body of academic research suggests that acoustic signals, or sound waves, produced when we type on our phones could be used by hackers to glean text messages, passwords, PINs and other private information. Such attacks could occur, experts say, if smartphone users were to download an app infected with malware that gains access to such smartphone sensors as microphones, accelerometers and gyroscopes.

One recent study, one of the latest demonstrations of hacking that exploits acoustics, found that the microphones in Android devices can be used to pick up the vibrations that are produced when you use the virtual keyboard on your phone or tablet. The sound waves that are recorded can then be interpreted to discern where on the screen you tapped and which keys you struck.