Eurekalert March 15, 2018
An international team of researchers (USA – University of Michigan, China) analysed a video sent by AP in which they heard a piercing, metallic sound. The spectral plot of the recording revealed a spectral peak near 7 kilohertz and a dozen other less-intense tones that formed a regular pattern with peaks separated by approximately 180 hertz. Based on their prior research the researchers hypothesized that intermodulation distortion can produce several by-products at other frequencies when multiple tones of different frequencies travel through air. Their math leads them to believe that intermodulation distortion is a likely culprit in the Cuban case, but they haven’t ruled out other null hypotheses that may account for the discomfort that diplomats felt… read more. Details in the Open Access article On Cuba, Diplomats, Ultrasound, and Intermodulation Distortion. Open Access Related Article DolphinAttack: Inaudible Voice Commands Video
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