In modern urban families, it is often complained that why the sound insulation doors and windows in aluminum alloy doors and windows are specially installed, and the noise at night still affects sleep? Although the sound insulation of doors and windows sounds quiet, we can not understand why the noise of doors and windows is still very good? Isn't it contradictory?
First of all, we exclude the quality problem of sound insulation doors and windows. The sound insulation effect of doors and windows has a great relationship with the quality and installation quality, but this problem can not be fully explained. Why are the same large brand doors and windows, some sound insulation effect is very good, and some sound insulation effect is very poor. To solve this problem, we should start from the source of sound.
The original sound has its own frequency. In high school physics, we know that each sound has its own unique frequency. According to the different frequency, we divide the sound into high-frequency sound and low-frequency sound (not strictly classified). The noise in daily life depends on the environment, and the frequency will also be different. What the sound insulation doors and windows can block is our ordinary people This is not a problem of doors and windows, because the low-frequency sound penetration is very strong, even the wall can easily penetrate.
High frequency sound in life:
Normal people chat, talk, sing (including TV, audio and other equipment), car whistle, all kinds of crash sound, thunder, rain, etc., in a less strict way, that is, the sound that we can easily hear can be called high frequency (relatively high frequency). These sounds are the most noisy and easy to be heard by people. Sound insulation doors and windows can be used for this kind of noise Sound insulation effect is very good, so, many people on the sound insulation doors and windows itself is more recognized.
Low frequency sound in life:
Electrical vibration, such as the hum of refrigerator and air conditioner, industrial machine tool, automobile guide, tire noise caused by friction between automobile tire and ground, whistling sound in sewer pipe, elevator motor, bass noise, and so on. In a less rigorous way, it is a noise that we don't pay attention to or easily cause resonance, In general, we are disturbed by low-frequency noise only when the high-frequency noise disappears or is very small. Therefore, we usually ignore the low-frequency noise. Only after "quiet", low-frequency noise begins to trouble us. The harm of low-frequency noise to human body is much higher than that of high-frequency noise. Moreover, low-frequency noise is almost impossible to prevent due to its strong penetration The control of frequency noise has become a worldwide problem. Low frequency noise can not only spread from the air, but also through structural transmission, which is difficult to defend.
To give a simple example: someone is knocking on the ladder guardrail with his hand in the stairwell. Can the whole building hear it? In addition, although the sound is not loud or noisy, it is very annoying to listen to. Moreover, if a building is decorated with percussion drill, the residents on the top of the building accidentally drop a coin and wait on the ground. Another common sense example is that the sound insulation effect of the car is very good. However, when we are close to a car, we usually can't hear what song is put in it However, the subwoofer can be heard more than 10 meters away from its subwoofer. No matter what high-grade car has, it can be heard from several meters away. The singing is the general medium and high frequency sound. The subwoofer is generated by air flow vibration, which is the most common low-frequency noise. If the subwoofer is played at home, it can be felt in a whole building That kind of thumping sound. At present, this kind of noise can only be solved from the source. No matter how good the doors and windows are, the sound insulation effect of this kind of noise is very poor. Even if the building wall is not subject to special seismic treatment, it can not block the low-frequency noise.