What is infrasound?

Classification: Life >> Common sense of life

Analysis:

Infrasound and infrasound source

Infrasound is a sound wave whose frequency is lower than audible sound, and its frequency range is approximately110000 Hz ~ 20 Hz. People can't hear infrasound. When infrasound propagates in the atmosphere, because of its low frequency, its absorption coefficient in the atmosphere is very small (the absorption coefficient is proportional to the quadratic power of frequency), so it can travel a long distance.

As early as the19th century, people have recorded infrasound waves produced by some accidental events in nature, such as volcanic eruption or meteor explosion. The most famous one was1August 27, 883, when Krakato volcano in Indonesia suddenly erupted, and the infrasound waves generated spread hundreds of thousands of kilometers. At that time, it could be recorded with a simple barometer. In 1930s, Soviet geophysicist B.B. Shulekin discovered infrasound waves generated by ocean waves. 196 1 year, the Soviet union conducted a nuclear explosion in the arctic circle, and the infrasound waves produced actually turned around the earth for five times before disappearing! Now known secondary sound sources are: earthquake, laser, airplane flight, meteor, aurora, ionospheric disturbance, clear sky turbulence, tsunami, typhoon, thunderstorm, tornado, lightning and so on.

Harm of infrasound

Although infrasound can't be heard by human ears, its destructive power is amazing. The natural frequencies of human organs and parts are between 0.0 1 ~ 20 Hz, which belongs to infrasound frequency range. High-intensity infrasound can cause strong vibration of internal organs, which can cause dizziness, vomiting, dyspnea, nausea, convulsions and shock, even coma, paralysis and even death.

Utilization of infrasound

As early as before the Second World War, infrasound was used to detect the position of artillery, but it was not until the 1950s that people began to pay attention to its application in other fields. Its application prospect is very broad, which can be roughly divided into the following aspects:

1. By studying the characteristics and mechanism of infrasound produced by natural phenomena, we can have a deeper understanding of the characteristics and laws of these phenomena. For example, people use the characteristics of infrasound produced by aurora to study the law of aurora agitation.

2. Use the received infrasound emitted by the measured sound source to detect its position, size and other characteristics, such as detecting the relevant parameters of these infrasound sources by receiving infrasound generated by nuclear explosion, rocket launching artillery or typhoon.

3. Predict natural disasters. Many disastrous phenomena, such as volcanic eruption, tornado and thunderstorm, may radiate infrasound before they occur, so it is possible to predict disastrous events by using these precursor phenomena.

4. When infrasound propagates in the atmosphere, it is easily influenced by atmospheric medium, which is closely related to atmospheric travel and temperature distribution. Therefore, by measuring the propagation characteristics of naturally or artificially generated infrasound in the atmosphere, we can detect the nature and laws of some large-scale meteorology. The advantage of this method is that it can continuously detect and monitor a large range of atmosphere.

5. By measuring the results of the interaction between infrasound and other fluctuations in the atmosphere, these activity characteristics can be detected. For example, in the ionosphere, the propagation of radio waves is disturbed by infrasound. By measuring the characteristics of infrasound, the law of ionospheric disturbance can be further revealed. Similarly, by measuring the interaction between sound waves and gravity waves or other fluctuations, we can study the activity law of these fluctuations.

6. People and other creatures can not only respond to infrasound, but also some of their organs will emit weak infrasound, so we can know the activity of the corresponding organs of human body or other creatures by measuring the characteristics of these infrasound waves.

Infrasound weapon

Infrasound weapon is a weapon device that is driven by a high-energy amplifier and emits high-power low-frequency sound waves below 20 Hz, that is, infrasound waves. Generally, it consists of infrasound generator, power device and control system.

At present, there are two kinds of infrasound weapons developed: one is nerve infrasound weapon, whose oscillation frequency is very close to the alpha rhythm of human brain (8 ~ 12 Hz), and when it produces * * * vibration, it can strongly * * * the brain, making people insane and unconscious; The other is visceral infrasound weapon, whose oscillation frequency is close to the natural oscillation frequency of human internal organs, which can make people's internal organs vibrate strongly, destroy people's sense of balance and direction, make people sick, vomit and feel seriously uncomfortable, and lose their combat effectiveness. Infrasound also has the characteristics of strong permeability. Once the infrasonic bomb hits the target, in the blink of an eye, everyone on the ground in Fiona Fang for more than ten kilometers will be hurt. Infrasound waves can penetrate 15m thick concrete and armored steel plates of tanks, even if people hide in subways, bomb shelters or tanks and armored vehicles. Infrasound bombs, like neutron bombs, only kill living things and do not destroy buildings, but their lethality greatly exceeds that of neutron bombs.

In order to prevent hijacking, the United States developed a infrasound gun. This new acoustic weapon can emit "acoustic bullets", that is, cluster sound waves. Powerful cluster sound waves can temporarily paralyze hijackers, thus preventing hijacking. But this kind of sound wave will not cause any damage to the plane itself. The newly added air police in the United States will be equipped with this new type of sonic gun.

The model of this new type of sonic gun was designed by American technology company headquartered in San Diego, California. Its main component is a polymer synthetic tube with a length of one meter and a diameter of 40 mm, which is composed of a series of piezoelectric devices. Each piezoelectric device is equivalent to a micro speaker. Every time the sound passes through a piezoelectric element, it will be strengthened and integrated. When the sound wave is emitted from the other end of the synthetic tube, it becomes a powerful sound wave, which can make people temporarily lose their sense of direction and even faint.

Norris, president of the American Institute of Technology, said: "This sonic gun can generate a cluster sound wave exceeding 140 decibels in 1 ~ 2 seconds." 120 ~ 130 decibels is enough to make people feel very painful. Norris, who has personally experienced the powerful power of this sonic gun, said: "When the bullet hit my head, I suddenly felt that I lost my cognitive ability to everything around me. I was completely scared by it. "

In fact, whether it is an infrasonic gun or an infrasonic bomb, the infrasonic wave with a frequency lower than 16 Hz, that is, the wave frequency generated by weapons, vibrates with the human body, so that the vibrating organ is deformed and displaced, thus achieving the purpose of harming the human body. Infrasound weapons generally consist of three parts: primary and secondary sound generators, power devices and control systems. The key of weapon is infrasound generator. The greater the power radiated by infrasound generator, the farther the killing distance. The advantage of infrasound weapons is that they can kill enemy personnel, but not necessarily the enemy. Instead, they can destroy the enemy's combat effectiveness without destroying enemy weapons and equipment, and they can arm themselves with enemy equipment.

At present, infrasound weapons have not really been used in the battlefield, but some countries are conducting experiments on hardware equipment, software configuration and biological effects. Some national experiments show that infrasound waves of 10 Hz and 190 dB can make dogs have difficulty breathing or even stop breathing. The higher the intensity of infrasound, the greater the lethality. In order to make the explosion effect produce high-intensity infrasound, foreign countries are still engaged in the research of infrasound bombs. This kind of infrasound bomb should belong to the nerve infrasound weapon, because it can paralyze people's nerves. There is an infrasound research institute in Marseille, France. It is said that the institute has developed three types of sound guns, namely "whistle", "acoustic leser" and "organ pipe sound gun", and said that these three weapons can kill people in fortifications, tanks and even submarines.

Although infrasound weapon is a powerful weapon, it also has congenital defects. First of all, infrasound is not easy to focus into a beam, and it is difficult to produce high-intensity infrasound in an open environment; Secondly, infrasound waves are very long and difficult to orient; Thirdly, its focus size is too large, which is generally difficult to achieve. Anyway, with the emergence of infrasound weapons, there is another way to kill people. ...

Infrasound case

1. The whale committed suicide.

1970 65438+1October1day, on the sea near Florida, USA, 150 small killer whales were suddenly washed up on the beach. People tried to drag them back to the sea, but the whales rushed to the beach again and again and all died.

Coincidentally, in July of 1979 and 17, whales were also found rushing to the beach, and 135 sperm whales were lying on the beach. The fishermen tried to drive them back to the sea, but they couldn't go back. All the whales died.

This kind of event caused scientists to think. Some people say that it is very likely that whales were killed by infrasound waves.

Scientists have found that whales swim in the water, measure their own direction and understand the surrounding situation, mainly by sending sound signals to the seabed, and determining their direction, position and depth according to the echoes. When its echolocation system was attacked by infrasound, the whale could not judge the direction and mistakenly thought that swimming across the shoal was the sea, but it ran aground.

Some scientists believe that the "devil" in Bermuda's "Devil's Triangle" is a strong infrasound wave with great destructive power, which is the main cause of the destruction of aircraft and ships and the death of crew.

Step 2: Death

There have been natural infrasound killings in history. 1890, a ship full of frozen mutton and plush-"Marpolo" sailed from New Zealand to England and disappeared. Twenty years later, it was found on the shore of Huodao. The dead crew members were all in their respective positions: 1 skull lying at the steering wheel, 3 on the hatch deck, 10 sailors on duty died in their respective posts, 6 "rested" at the bottom of the cabin, and clothes fragments remained on the remains. 1948, a more amazing thing happened on a ship named "Wulange Medak". The wireless telegrapher patted the SOS international distress signal and reported intermittently: "The captain and crew are dead ... I will die soon." Rescuers froze their faces when they saw all the sailors dead in their posts.

How did the crew die? Did you die of skyfire or lightning? No, because there are no signs of burning on the ship; Did you die by the pirate's sword? Don't! The remains of the victims showed signs of fighting before their death; Did you die of hunger and thirst? Not really! There is always enough food and bonfire on board. The test results showed that no scars were found on all the victims, and there were no signs of poisoning. So, is it because of the sudden attack of cardiovascular and cerebrovascular diseases? The autopsy report of the forensic doctor shows that the deceased were all strong before his death!

After years of research and experiments, it is confirmed that the culprit of these sunken ships is probably infrasound generated on the vast sea surface, that is, high-energy infrasound oscillation generated by galloping wind and stormy waves in the air.

Generally, ocean infrasound appears in storms and strong winds, and its frequency is lower than 2 Hz. The energy of infrasound is determined by the degree of wave and current rupture at the peak. In hurricane weather, this kind of infrasound with an average of 6 Hz reaches tens of kilowatts, even hundreds of kilowatts, and can spread to thousands of kilometers. When this powerful infrasound "surrounds" the ship, it can undoubtedly kill everyone on board in a few seconds.

In view of the above situation, some countries have established institutions to predict infrasound waves. When it receives a life-threatening infrasound, it will immediately report to the relevant parties to reduce the harm caused by ocean infrasound to seafarers.