With the help of an ordinary polyethylene film can make the walls almost completely permeable to sound

For the interesting physical experiments are not necessary to have expensive equipment: Japanese and Korean scientists have succeeded with the help of polyethylene film to make a wall almost completely zvukopronitsaemymi.

First you need to make a hole in the barrier, then the sound will be louder, but if you close the hole on top of the film layer of the food, the impression that the sound wall does not exist.

Researchers have experimented with many materials, including a thin layer of rubber, but came to the conclusion that it is polyethylene, which is used for storage of products is ideally suited for the transmission of sound.

The principle of operation is as follows: the empty slot passes the audio signal, but vibrations in the air repeatedly reflected from the walls of the hole, with the result that there is a pressure difference, which prevents a significant improvement in hearing. A thin plastic layer is vibrating, pushing the excess air from the back side of the wall - in which case the pressure equalized. And if the pressure difference either one or the other side of the barrier is not present, and for the sound barrier itself does not physically exist.

In some experiments, the polyethylene was able to pass only 75% of the audio signal, but carefully calibrated hole size, the accuracy can be increased to 97%.

via factroom.ru