What Is Noise Level?

Noise is a type of sound that causes irritability or is too loud to endanger human health ^[1] .

Definition. A unit to measure the change in sound volume, in dB. It is the ratio of the volume of two sounds, expressed as a logarithm. Calculation formula: decibel = 10log volume A / volume B ^[4]

1. Reduce noise at the sound source ^[8]

First, white noise

The energy of white noise at a frequency point in the entire frequency spectrum is constant and basically constant. No matter whether the signal is processed by a low-pass filter or a high-pass filter, white noise cannot be effectively removed because it exists in the entire frequency band . White noise is random, it has no correlation, so there is no deviation. Therefore, white noise can be superimposed on signals and algorithms, or always exist in the A / D converter without causing long-term bit errors. With proper processing, white noise can also be used to create sounds, including human and natural sounds, and even synthesize other noises ^[9]

There are many concepts to decibels, which are generally physical quantities that describe the size of sound. Hearing loss

With the development of modern industry,

Noise, like everything else, has both a harmful side and a side that can be used and benefited by humans. Many scientists have done a lot of research work on noise utilization:

In 1991, an Austrian research institute developed a sound-absorbing cement highway. This concrete cement highway has the same pores and elasticity as foam materials, which can convert a large amount of vibration energy into heat energy inside the material and dissipate it. Vibration and noise rapidly decay ^[21] .

Japanese scientists use a new type of "sound equipment" to turn the noise of various flowing waters in family life, such as washing hands and washing rice, into a pleasant concerto. The United States has also developed a synthesizer that absorbs the noise of big cities and turns it into the "music sound" of nature. British scientists have also developed the "white noise" of the hair dryer sound and thus produced a "baby hypnosis". Make babies and children naturally dormant ^[21] .

Noise is a sound wave, so it is also an energy. Experts from the University of Cambridge in the United Kingdom have begun to use noise to generate electricity. They designed a tympanic acoustic receiver. This receiver is connected to a resonator and placed in a noise-contaminated area to convert acoustic energy into electrical energy. American researchers have found that high-energy noise can bring dust particles together and produce better dust removal effects ^[21] .

What is more meaningful in the field of scientific research is the method of using the noise to see the ocean floor. Scientists use the noise in the ocean, such as broken waves, fish swimming, rain, the disturbance of passing ships, and so on, to use sound as the "light source" for photography. In 1991, American scientists first used this wonderful photographic function to make successful experiments in the Pacific Ocean ^[21] .

The application of noise to crops has also achieved surprising results. Scientists have found that plants are able to absorb more carbon dioxide and oxygen after being stimulated by sound, thereby increasing growth rate and yield. Experiments have found that crops such as rice, soybeans, and cucumbers have increased yields to varying degrees under the influence of noise. Perhaps, in the near future, the annoying noise will become a beautiful new song for the benefit of mankind ^[21] .