Hello, this is Mr.I of Shizuka Co., Ltd..

In today’s article, I would like to mention about secrets of sound absorbing materials.
※original article in Japanese (日本語の記事)

In general, materials with an air layer inside are effective for sound absorbing materials. The existence of this air layer converts sound energy into thermal energy and reduces sound reflection. However, no matter how much air layer is kept inside, it is impossible to convert it into thermal energy unless there is breathability for sound to enter inside.

For example, there is a theory that attaching an egg pack to a wall will reduce reflections, but this is a story if the egg pack material is paper. It is counterproductive because transparent polyethylene has no breathability.

Although the air layer may be sorted by thickness, there are limit values depending on each material. This is due to the fineness of the bubbles of the material. As for urethane foam which is representative of sound absorbing material, the sound absorbing effect changes according to expansion ratio. Sound absorbing materials are also used for industrial use, so if you purchase unexpected industrial products you may be able to suppress them at a low price. 

By the way, styrofoam and styrene foam for building materials should not be used as sound absorbing material! Although it looks like a sound absorbing material, it is not possible to absorb sound because “air bubbles” are said to be independent of the holes in the air layer.

Continue to the next article “Secret of sound absorbing material ②“.