Sound is produced by the vibration of objects. The faster an object vibrates, the higher the frequency of the sound it emits, and vice versa. The eardrum is the main organ for people to listen to external sounds, which has a certain limit on the frequency of sound, that is, in the range of 20 ~ 20~20000Hz. If the frequency is too high, it is ultrasonic waves, such as radio waves. We can't hear you. If the frequency is too low, it is called infrasound, so we can't hear it.
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Infrasound is a sound wave with a frequency of 0.000 1 ~ 20 Hz, which is usually inaudible to human ears. The essence of infrasound is vibration.
* * * Vibration is a very common technical term in physics. * * * Vibration is defined as the phenomenon that when two objects with the same vibration frequency vibrate, the other object vibrates.
For example:
Because every part of the human body has a subtle and rhythmic pulse, the frequency of this pulse is generally 2 ~ 16Hz, such as 4 ~ 6Hz for internal organs and 8 ~ 12Hz for the head. These natural frequencies of human body are just within the frequency range of infrasound. Once high-power infrasound acts on human body, it will cause strong vibration of human body, thus causing great harm.
The same principle applies to buildings and airplanes.
Infrasound is a sound wave with a frequency of 0.000 1 ~ 20 Hz, which is usually inaudible to human ears. Because every part of the human body has a subtle and rhythmic pulse, the frequency of this pulse is generally 2 ~ 16Hz, such as 4 ~ 6Hz for internal organs and 8 ~ 12Hz for the head. These natural frequencies of human body are just within the frequency range of infrasound. Once high-power infrasound acts on human body, it will cause strong vibration of human body, thus causing great harm. Speaking of the destructive power of * * * vibration, many readers may know that in Europe in the19th century, many soldiers crossed the bridge in unison, which led to the tragedy that the bridge collapsed due to vibration. No matter how strong the bridge is, it can be destroyed by vibration, let alone flesh and blood! Infrasound weapons are weapons that use infrasound waves with a frequency lower than 20Hz to vibrate with the human body, so that the vibrating organs or parts are displaced and deformed, resulting in human injury or even death.
Meteorite landing, ocean storm,
Infrasound waves are widely used in artillery firing and missile flight in human activities.
Harm of infrasound
Infrasound waves widely exist in nature and human activities, and people gradually realize its magical power through the damage caused by infrasound waves.
1883, Clatot volcano erupted, and the huge eruption aroused a powerful infrasound. It circled the earth three times. This infrasound was detected at an observation station tens of thousands of kilometers away from the volcano. This is the first infrasound recorded in the world.
1948, a Dutch cargo ship named "Ulan Gomez" suddenly encountered a storm while passing through the Straits of Malacca. When the rescuers arrived, all the people on board died inexplicably. After investigation, scientists found that the culprit of this shipwreck was infrasound caused by storms and rough seas. Recently, some people blame this on infrasound waves in the mysterious Bermuda Triangle.
In nature, ocean storms, volcanic eruptions, meteorite falls, tsunamis, lightning and thunder, waves hitting the coast, eddies in water, turbulence in the air, tornadoes, magnetic storms, auroras and so on. May be accompanied by infrasound waves.
In human activities, such as nuclear explosion, missile flight, artillery shooting, ship navigation, car galloping, high-rise bridges shaking, and even blowers, mixers, loudspeakers and so on can produce infrasound waves.
In order to deeply understand how strong infrasound the human body can withstand, people have done experiments with dogs, monkeys and baboons with similar endurance to the human body. The results showed that under the high-intensity infrasound of 172dB, dogs had obvious breathing difficulties, and some even stopped breathing, and the breathing times of monkeys and baboons also decreased significantly. When the sound pressure level reached 185 ~ 195 dB, all animals died in a short time. After repeated research, scientists generally believe that the infrasound intensity is around 140dB, even if the action time is very short, it will cause changes in the function of human internal organs. When it rises to 150dB, it will cause pathological changes of some organs in human body. For example, if infrasound intensity rises again, not only will there be obvious changes in physiology and pathology, but it will even lead to personal injury. Therefore, the sound pressure level of 150dB is regarded as the safe limit for human body to bear infrasound.
Infrasound weapon fever has arisen abroad.