Does the sound of the air raid sirens make you nervous? It turns out that sound has such an effect

In the movie "Air Battle", a Mirage 2000 flying at supersonic speed over an enemy base produced a sonic boom that was enough to instantly shatter everyone's eardrums and shatter car glass and windows. Like a sonic boom, it is the shock wave generated by an aircraft flying at supersonic speed that propagates on the ground to form an explosion sound.

Because the planes are flying faster than the speed of sound, the density waves they emit cannot pass in front of them, so all the planes are stacked behind the fuselage, forming a cone-shaped sound cone. When this wave arrives, we can hear all the sounds, and in hearing, this is a loud sonic boom.

Sonic booms look very cool, especially when fighter jets fly at supersonic speeds. The sonic booms produced are very beautiful, but at the same time, the destructive power of sonic booms is also astonishing.

When a fighter jet flies over a residential area at twice the speed of sound at an altitude of 16,000 meters, the sonic boom produces a force equivalent to 10 kilograms per square meter of building area. Today, the fastest fighter jet in the world has a speed of 6.67 times the speed of sound per second. If this plane flies too low, it will bring disaster to the local area. Therefore, all countries prohibit supersonic flights over their own countries.

In addition to the volume, the tone and timbre of a sound also contain tremendous energy. For example, some sounds can make people feel fearful, some sounds can make people sad and cry, and some sounds can make people happy.

Research in recent years has shown that some special sounds or music can cure diseases. When sound enters the human body, it becomes an electric wave, and many human nerves are expressed in the form of electric current and electric waves. Therefore, specific sounds can have a huge effect on the human body. For example, listening to alpha brainwave music can significantly improve concentration and memory. At the same time, this is also the only kind of music that can be listened to while doing homework and is helpful for learning.

On September 18 this year, air defense sirens rang out in cities across the country, lasting from a few minutes to dozens of minutes. Ninety years ago on this day, the September 18th Incident broke out, and Japan launched a 14-year-long war of aggression against China, starting from Shenyang.

September 18th is a day that every Chinese should remember. The sounding of the air raid sirens is to remind us to remember history and not forget the national humiliation.

As for the sound of the air defense alarm, I believe everyone has a deep feeling. This kind of sound not only goes straight into the heart, but also sounds very mournful, low, long and sad, which can easily make people feel a sense of crisis and a strong sense of urgency. This is mainly because the sound of the air defense alarm uses a prompt tone that goes from far to near. This change in distance will give people a continuous psychological hint, making people alert physically and mentally.

In addition, the loudspeakers for air raid sirens are located in almost every city in the country, and they are placed very high up, so the sound can travel very far. Moreover, the placement of air raid sirens follows Doppler's law.

The so-called Doppler law can be simply understood as follows: if an object that emits sound waves moves towards a person at a relatively fast speed, the sound waves will be compressed. After compression, the frequency of the sound will be high and it will become sharp. When the object that emits sound moves away from a person, the sound waves will be stretched and the sound will become low. The psychological suggestion of getting closer and farther away, the high volume and the sharp and piercing tone change make the air defense alarm have a super strong warning effect.

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