US warns staff in China: Beware of unusual sounds


Types of sonic weapon

Infrasound - below 20Hz

  • at frequencies too low for humans to hear
  • if very loud can cause vertigo, vomiting or uncontrollable defecation!!!
  • would need huge racks of speakers to be effective

Ultrasound - above 20,000Hz

  • easier to target
  • possible to direct sound through walls
  • risk of affecting people other than those targeted, including person carrying out attack


US warns staff in China: Beware of unusual sounds - BBC News