In order to use insulation materials for sound insulation, we must first understand the structure of insulation materials and the principle of sound insulation. Sound is generated by vibration, to air, liquid, solid transmission, when the sound meets obstacles, there will be reflection, refraction, scattering and other phenomena, the use of these characteristics can hinder or reduce the transmission of sound.

The quality of the insulation material is large enough to absorb part of the sound and hinder the transmission of the sound; There is air inside, which will collide with air molecules and cause energy loss; The multi-layer structure makes the sound repeatedly reflect, refract, scatter and other phenomena to consume the energy of the sound.
Based on the above characteristics, the insulation material must have the physical characteristics of large mass, internal air and multi-layer structure to have sound insulation effect. Insulation materials with excellent sound insulation properties are glass wool, rock wool, rubber and plastic, aerogel and so on.

Glass wool and rock wool belong to the fluffy fiber open-hole structure, when the sound meets the glass wool and rock wool, a part of the sound will be blocked, and the sound entering the interior will be consumed by the air and the fiber repeatedly until the sound disappears.
Rubber is also based on this principle, the only difference is that rubber belongs to the closed-cell foam structure, the interior is composed of countless closed holes, so the sound absorption and sound insulation effect will be better.
Aerogel is a three-dimensional nanoporous network structure, air or gas accounted for 97%, when the sound into, reflection, refraction, scattering and other frequencies are more frequent, so the sound insulation and absorption performance is better.
Insulation materials with large mass, internal air, multi-layer structure and other physical characteristics are effective for sound insulation. In addition to the material will affect the sound insulation performance, the thickness and density of the material will also affect the sound insulation performance, in general, the thicker the material, the greater the density, the better the sound insulation performance.