A team of researchers at the State University of Florida in Tallahassee say sonar is the way to beat spoofing attacks on voice biometrics.Yang and his colleagues have devised a technology that detects and defeats such misuse of recordings.Called VoiceGesture, it is able to not only recognise that a passphrase has been said but also sonar vibrations caused by the user.In the team's paper, “Hearing Your Voice is Not Enough: An Articulatory Gesture Based Liveness Detection for Voice Authentication”, they outline how their system detects a live user by leveraging both the unique articulatory gesture of the user and the passphrase.The system re-uses the smartphone as a Doppler radar, which transmits a high frequency acoustic sound from the built-in speaker and listens to the reflections at the microphone when a user speaks a passphrase.Their experimental evaluation with 21 participants and different types of phones shows that it achieves over 99% detection accuracy at around 1% Equal Error Rate (EER). Results also show that it is robust to different phone placements and is able to work with different sampling frequencies