There are high and low voices, some we can hear and some we can't hear. In physics, sound waves are divided according to the frequency of sound, that is, the number of vibrations. There is a standard called Hertz. People's ears can hear sounds within a certain range. If the frequency is higher than 20000 Hz, people can't hear it. This is called ultrasound. Ultrasound can be used to diagnose diseases in medicine and to detect whether there are impurities in metals in industry. In addition, people can't hear sound waves with a frequency below 20 Hz, which is called infrasound. The frequency of infrasound is very close to the natural frequency of human organs. People have all kinds of organs, all of which are vibrating. When there is vibration, there is frequency. If infrasound waves act on human body, organs with the same natural frequency as secondary waves will involuntarily produce * * * vibration, causing damage to human organs. Infrasound weapons use this mechanism to kill people.
At present, two kinds of infrasound weapons have been developed. One is the infrasound weapon that harms the human brain and destroys nerves. It emits infrasound with a frequency of 8 ~ 12 Hz. This infrasound vibrates with people's brains, impairing people's nervous system, affecting people's consciousness and psychology, making people feel uncomfortable, unable to concentrate, and difficult to engage in complex and meticulous work. Sometimes there will be headache, nausea, rapid heartbeat, fear and anxiety. And in severe cases, people will be insane, go into shock and lose their thinking ability. The other is an organ-killing weapon that destroys internal organs, emitting infrasound waves of 4 ~ 8 Hz, which is close to the vibration frequency of human internal organs. Infrasound waves vibrate strongly with human viscera, which can cause muscle spasm, whole body trembling, dyspnea, organ rupture, visceral injury and even death.