Causing microphones to detect inaudible sounds and defense against inaudible attacks

Nirupam Roy (Inventor), Romit Roy Choudhury (Inventor), Haitham Al Hassanieh (Inventor)

Research output: Patent


An audio transmitter includes a first ultrasonic speaker associated with a first channel; a second ultrasonic speaker co-located with the first ultrasonic speaker and associated with a second channel; and a waveform generator to: frequency modulate a first inaudible signal at a first ultrasonic frequency, to generate a modulated inaudible signal; drive, over the first channel, the first ultrasonic speaker with the modulated inaudible signal; and drive, over the second channel, the second ultrasonic speaker with a second inaudible signal at a second ultrasonic frequency so that a combination of the modulated inaudible signal and the second inaudible signal arrive at a microphone system. The second ultrasonic frequency is selected to frequency shift the modulated inaudible signal, upon demodulation by hardware of the microphone system, causing non-linearities of the hardware to translate the first ultrasonic frequency to below a low-pass filter cutoff frequency that is recordable by the microphone system.
Original languageEnglish (US)
U.S. patent number10672416
Filing date10/17/18
StatePublished - Jun 2 2020


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