Our world is filled with sounds generated as a living and inanimate nature. Natural sounds cause people various feelings. So, the thunder or the roar of the wrath of the sea can cause terror, and the rustling of trees, the rustle of grass or dimensional waves rolling on the shore give us a joyful mood or light sedation.
Sounds born out of nature, also cause us to respond. Since then, as people with the help of technology began to conquer nature, the world began to spread sounds different as for originality, and his power. Today the noise in many areas has taken such a strong position that its action leads to changes in the environment. Sound pressure can even cause fluctuations subjects; for example, when the roar of a passing airplane rattle the window panes.
Noise pollution has become one of the problems in human life. Especially dangerous noise for sick people. Many of them Wake up even with a light rustle and almost can not sleep in the big city.
For long the noise of the person responds differently than on a periodic and repetitive. Some people comes dulling the perception of noise. But scientists have proved that the noise cannot be used: even if we learn not to get irritated from it, it will still cause us harm. And not only us, but our smaller brothers.
Biologists have only recently learned that, for example, fish is not silent. They send each other signals lying outside the hearing threshold of a person. Ultrasound helps to focus bats and dolphins.
Dogs and cats also perceive sound signals lying outside of our hearing. Animals suffer from noise very much. There are known cases of mass death of poultry from the constant noise of the aircraft. From their sonic boom sometimes bursts the shell unprotected eggs.