Research demonstrates how vibration motors in wearables can be used to "listen" to speech

CSL Associate Professor Romit Roy Choudhury and ECE PhD Candidate Nirupam Roy knew that vibrating objects generally respond to air vibrations, so it stood to reason that the vibration motor in a smartphone could act as a microphone. They made an unexpected discovery when they came to understand that the output of these vibra-motors needed only basic signal processing to recognize the words and phrases. The two have published their findings in a paper, "Listening through a Vibration Motor."

The implications of their research present new opportunities and threats.

"Even modest reproduction could prompt new applications and threats. On one hand, wearable devices like fitbits, that otherwise do not have a microphone, could now respond to voice commands…On the other hand, leaking sound through vibra-motors opens new side channels - a malware that has default access to a phone's vibra-motor may now be able to eavesdrop into every phone conversation," wrote Roy and Choudhury, a professor of electrical and computer enigneering and computer science.