What is sound absorption and sound insulation?

When a sound wave injected the material surface, one part of incident sound energy was reflected, the second part got into the internal material and was absorbed, and the last part penetrated the material to get into another side of material. When the majority of sound energy got into material (be absorbed or projection), but the energy of reflection was small, it showed that the sound absorption performance of material was good. When the sound absorption coefficient was greater than 0.2, it can be called sound absorption material. Using material or component to insolate or stop the spread of sound to obtain a quiet environment was called sound insulation. When the sound injected to material surface, and the sound energy of projection that penetrated material to get into another side was small, it showed that the sound insulation of material was strong. The decibel difference between incident sound energy and another side’s sound energy of projection was the sound insulation volume of material. From the above description, it can be seen that sound absorption material focus on the size of sound energy of reflection in one side of sound source, aiming at smaller sound energy of reflection; sound insulation material focus on the size of sound energy of projection in another side of incident sound energy, aiming at smaller sound energy of projection.