Acoustic waves are mechanical longitudinal waves, which can propagate in solids, liquids and gases. The sound that people can hear every day is the sound wave in the frequency range of 20-20-20000Hz. Below 20Hz is infrasound. The reason why infrasound is used as a military weapon is because infrasound is similar to the natural frequency of human organs, so it will produce * * * vibration. Infrasound and the vibration of human organs will lead to the deformation, displacement and even rupture of organs, thus achieving the purpose of killing people.
Infrasound weapons can be roughly divided into two categories: nerve infrasound weapons and organ infrasound weapons.
The infrasound frequency of "nerve-type" infrasound weapon is very close to the alpha rhythm of human brain (8- 12hz), so when infrasound acts on human body, it will stimulate human brain and cause * * * vibration, which will have a certain impact on people's psychology and consciousness: light people feel uncomfortable, lose concentration, feel uneasy, and lead to dizziness and nausea; In severe cases, people are insane, crazy, shocked, fainted and lose their thinking ability.
The infrasound frequency of "organ-type" infrasound weapon is close to the natural frequency of human viscera (4- 18Hz), which will cause strong vibration of human viscera. Mild muscle spasm, whole body trembling, difficulty breathing; In severe cases, blood vessels rupture, visceral injury, and even rapid death.
The advantages of infrasound weapons are:
(1) Surprise. The propagation speed of infrasound in air is more than 300 meters per second (1200km/h), and it is even faster in water, reaching about 1500m/h (6000km/h). Infrasound is inaudible and invisible to ordinary people, so it not only spreads quickly, but also has good concealment.
② The action distance is far. According to the principle of physics, the lower the frequency of sound wave, the less it is absorbed by the medium and the farther the wave propagates. Such as the production of artillery shells.
The audible sound wave can't be heard several kilometers away because of its fast attenuation, but the infrasound wave it produces can spread to 80km kilometers away; Infrasound waves produced by hydrogen bombs can circle the earth several times and travel hundreds of thousands of kilometers. Therefore, high-intensity infrasound weapons have intercontinental combat capability.
③ Strong penetrating power. The propagation medium has little absorption of low-frequency sound waves, so the penetration ability of infrasound waves is very strong. Ordinary audible sound waves can be blocked by a wall, but experiments show that infrasound waves can penetrate reinforced concrete with a thickness of tens of meters. Therefore, whether the enemy is hiding in a bunker, riding in Tanqueray or in a submarine in the deep sea, it is difficult to escape the attack of infrasound weapons.
(4) infrasound can kill the enemy, at the same time, it will not cause environmental pollution, nor will it destroy the opponent's weapons and equipment, so it can be used as a trophy.
It should be pointed out that the intensity and directionality of infrasound emitted by infrasound weapons need to be further studied, so infrasound weapons really used in war are rare. It is said that the first infrasound generator was invented by French scientist Gabriel in 1972. The infrasound generated by it can hurt people 5 kilometers away. The inventor also concluded that infrasound with a frequency of 7Hz can cause fatal blow to human body.
It is said that during the wars in Somalia and Bosnia and Herzegovina, the US military tried some samples of sound or sound weapons. These weapons can make people's internal organs vibrate, make people unconscious, make people sick, and even make the feces in the intestines liquefy and diarrhea constantly, thus losing their combat effectiveness.
During World War II, the Germans began to secretly develop infrasound weapons, trying to use its "loud effect" to destroy the whole city, destroy the enemy or make it lose its combat effectiveness. During 1940, the Germans planned to throw phonograph records signed by famous musicians at the British people. These records will be specially recorded and added with infrasound, which will cause mental disorders such as panic and terror to listeners, thus causing riots. Of course, this plan has not been realized. However, Nazi scientists successfully conducted experiments on infrasound weapons that could be used on objects. Austrian scientist Chipmeyer has made a kind of "cyclone gun" that can make cyclones. It uses a special nozzle to create a whirlwind by blasting shells and launch attack waves, which can shoot down planes.