The sonic boom is so powerful that a low-altitude supersonic fighter can produce enough sonic boom to shatter windows and doors. So when the sonic boom happens, the sound is very loud and the penetration is relatively strong, so what is the sonic boom? What is the principle of the sonic boom?
When the speed of an object is close to the speed of sound, there will be a strong resistance, which will cause the object to produce strong oscillation and speed decay. This phenomenon is commonly known as sound barrier. When breaking through the sound barrier, due to the compression of the air by the object itself, it can not spread rapidly, gradually accumulating in the windward area of the object and finally forming the shock wave surface, on which the acoustic energy is highly concentrated. When these energies are transmitted to people's ears, people will feel the short and extremely strong explosion sound, which is called sonic boom.
What is the principle of sonic boom?
Sound explosion sound propagates in the air just like the water wave generated by putting stones into the water, and propagates outward in the form of wave, which is called sound wave. The sound we usually hear is generated by the sound wave entering the ear and making the tympanic membrane vibrate. When an aircraft is flying at supersonic speed in the air, a wedge-shaped or conical wave will appear in the nose or protrusion of the aircraft, just like a speedboat moving forward in the water. This is a shock wave. The dense sound waves emitted by the aircraft can not run to the front of the aircraft, so they are all stacked behind the fuselage, forming a cone-shaped sound cone. When they propagate outwards, they interfere and influence each other. Then they integrate a front sonic shock and a rear shock with a random tail. Although this kind of wave can be compared with the wedge-shaped water wave mentioned above, it has different properties. The thickness of shock wave is very small. After the shock wave, the pressure, density and temperature of air suddenly increase, and the speed immediately decreases. When these two exciting waves reach any space or object, they will feel this strong change, which is reflected in the ears of people, making the eardrum membrane subject to the sudden change of air pressure, and then it will feel like two thunders. This kind of noise is called "sonic boom".