Researchers from Stanford and a defence research group at Rafael will demonstrate a way to spy on smartphones using gyroscopes at Usenix Security event on August 22, 2014.
According to the 'Gyrophone: Recognizing Speech From Gyroscope Signals' study, the gyroscopes integrated into smartphones were sensitive enough to enable some sound waves to be picked up, transforming them into crude microphones.
Researchers noted: "We show that we can use gyroscopes to eavesdrop on speech without using the microphone at all, which can potentially risk private information such as identity, social security and credit card numbers.
"We show that the acoustic signal measured by the gyroscope can reveal private information about the phone's environment such as who is speaking in the room and, to some extent, what is being said.
"We use signal processing and machine learning to analyse speech from very low frequency samples.
With further development on such low-frequency signal processing researchers claim it has to be possible to raise the quality of the information pulled out from the gyroscope."
The researchers added: "We achieve about 50% success rate for speaker identification from a set of 10 speakers.
"We also show that while limiting ourselves to a small vocabulary consisting solely of digit pronunciations ("one","two", "three", ...) and achieve speech recognition success rate of 65% for the speaker dependent case and up to 26% recognition rate for the speaker independent case."