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Question - could you just send ultrasound though the walls just like the wifi signals in this example? I guess I'm not sure how much more limited ultrasound wou

• jacquesm 4y ago
  No. Ultrasound will not make it to the other side of a wall, especially not an outside wall.
  • TEP_Kim_Il_Sung 4y ago
    Infrasound could, but the speakers might not be big enough, unless you use the amplitude trick.
• phh 4y ago
  It doesn't go through walls, so they are pretty much the right tools for the job. They are known vulnerable to lasers, but well microphones themselves are, so...