"Sonic attack" may have been two ultrasonic signals accidentally interfering
> Yan was even able to embed an ultrasonic version of the Rick Astley song “Never Gonna Give You Up,” which became audible at the point where the two signals crossed.At 33C3 I rode an escalator when I suddenly heard "Never Gonna Give You Up" but apparently no one else did. It was over after a few seconds. At the top of escalator there was a guy pointing a directional speaker at random people.Only reference I could find is in German, but it has a picture [1].
The story says the guy on the picture is not the inventor of the device.EDIT: The thing is a parametric ultrasonic speaker and the design files and software are on GitHub [2].[1] https://motherboard.vice.com/de/article/784z74/33c3--hacker-...[2] https://github.com/niklasfauth/parametricspeaker