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As the sound wave propagates through the medium, the sound energy will inevitably weaken as the distance increases.

The so-called acoustic glass is a special medium that greatly reduces the energy of sound waves. Even ordinary glass has a certain effect of attenuating sound waves, but it is not so effective.

Sound insulation glass, whether it is laminated glass, insulating glass, vacuum glass, etc., applies the following two basic principles:

( 1 ) When sound waves propagate from one medium to another, at the interface of the two mediums, part of the energy is reflected back to the original medium, and another part of the energy is transmitted through the interface in the other medium. When sound waves encounter interfaces with different acoustic impedances (air and solid interfaces, vacuum and solid interfaces), scattered reflections cause attenuation, ie, scattering attenuation. To put it bluntly, it is difficult for sound waves to pass through the middle layer in the glass, and then most of it is reflected. The middle layer may be air or even vacuum. Moreover, the greater the difference in acoustic impedance between the two media at the interface, the higher the reflectivity, the greater the difference in acoustic impedance between air and glass.

What is acoustic impedance? Acoustic impedance can be understood as describing the media's resistance to particle vibration. At the same sound pressure, the acoustic impedance increases, which causes the vibration speed of the particle to decrease. This is similar to the resistance concept of Ohm's law in electricity.

( 2 ) Attenuation due to internal friction and heat conduction between particles in the medium, ie absorption attenuation or viscous attenuation. To put it bluntly, the film material of the glass and the interlayer sandwich (for example, a PVB interlayer film containing polyvinyl butyral as a main component, a KK superelastic interlayer film containing a polymer as a main component, etc.) causes the sound wave to overcome the resistance work. , so that the sound energy is weakened.

In this way, the principle of absorption and attenuation is mainly applied to laminated glass, and the principle of scattering attenuation is mainly applied to insulating glass and vacuum glass.