Abstract: Techniques are provided for detection of laser-based audio injection attacks through classification of the acoustic environment. A methodology implementing the techniques according to an embodiment includes broadcasting a reference signal over a loudspeaker into a local environment, and generating a reference model of the local environment based on analysis of a transformed version of that reference signal received through a microphone of the device. The method further includes generating an estimate model based on analysis of a segment of speech in an audio signal received through the microphone. The estimate model is associated with an environment in which the speech was generated. The method further includes calculating a similarity metric (e.g., mathematical distance) between the reference model and the estimate model, and providing warning of a laser-based audio attack if the similarity metric exceeds a threshold value associated with an attack.

Abstract: Techniques are provided for defending against an ultrasonic attack on a speech enabled device. A methodology implementing the techniques according to an embodiment includes detecting voice activity in an audio signal received by the device and generating an ultrasonic jamming signal in response to the detection. The jamming signal is broadcast over a loudspeaker for up to the duration of the detected voice activity to defend against the ultrasonic attack. According to another embodiment, the ultrasonic jamming signal is generated in response to detection of a wake-on-voice key phrase in the received audio signal, and the jamming signal is broadcast over the loudspeaker for a time duration selected to be less than or equal to a time window during which spoken commands are accepted by the device following the wake-on-voice key phrase detection. The jamming signal may include white or colored noise, combinations of tones, and/or a periodic sweep frequency.

Abstract: Techniques are provided for defending against an ultrasonic attack on a speech enabled device. A methodology implementing the techniques according to an embodiment includes detecting voice activity in an audio signal received by the device and generating an ultrasonic jamming signal in response to the detection. The jamming signal is broadcast over a loudspeaker for up to the duration of the detected voice activity to defend against the ultrasonic attack. According to another embodiment, the ultrasonic jamming signal is generated in response to detection of a wake-on-voice key phrase in the received audio signal, and the jamming signal is broadcast over the loudspeaker for a time duration selected to be less than or equal to a time window during which spoken commands are accepted by the device following the wake-on-voice key phrase detection. The jamming signal may include white or colored noise, combinations of tones, and/or a periodic sweep frequency.