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.