(1) Use noise to weed.
Scientists have found that different plants are not sensitive to different noises. According to this truth, people made a noise herbicide. The noise generated by this noise herbicide can make the seeds of weeds germinate ahead of time, so that weeds can be removed with drugs before crop growth, and the smooth growth of crops can be ensured through the clever strategy of "playing hard to get".
(2) Using noise to generate electricity
Noise is a kind of energy pollution, such as noise reaching 160? DB jet, its sound power is about 10000? w； Noise as high as 140? The sound power of a large blower is about 100 in dB? W. "Gathering sand into a tower" naturally attracted the interest of new energy developers. Scientists have found that artificial lithium niobate has the special function of converting acoustic energy into electrical energy at high frequency and high temperature. Scientists also found that when sound waves meet obstacles, acoustic energy will be converted into electrical energy. Based on this principle, British scholars have designed and manufactured a tympanic membrane acoustic wave receiver, which is connected with a buzzer that can increase acoustic energy and concentrate energy. When the sound energy from the buzzer acts on the acoustoelectric converter, electricity can be generated. Seems to use.
(3) using noise for refrigeration
As we all know, refrigerators can be refrigerated, but it is encouraging that a new refrigeration technology is being developed internationally, that is, a new technology using weak acoustic vibration for refrigeration. The first prototype has been successfully trial-produced in the United States. In an unusually simple structure with a diameter less than 1 M's cylinder is made up of several glass fiber plates with heat transfer function, and the cylinder is filled with helium or other gases. One end of the cylinder is sealed, and the other end is sealed with an elastic diaphragm. The wires on the diaphragm are connected with the magnetic voice coil to form a microphone. Sound waves act on the diaphragm, causing back and forth vibration, thus changing the pressure of gas in the cylinder. Because gas becomes hot when compressed and cold when expanded, refrigeration begins. It is not difficult to imagine that if these factors can be taken into account in buildings such as houses and factories in the future, the invisible scourge of noise can be overcome in one fell swoop, and buildings such as houses and factories can cool down and cool off the heat.
(4) using noise to remove dust
American researchers have developed a power of 2? KW dust alarm, can send out a frequency of 2000? Hz, the sound intensity is 160? Decibel noise, the device can be used for chimney dust removal and control dust particles and air pollution in high temperature, high pressure and high corrosion environment.
(5) Use noise to defeat the enemy.
Noise can also be used to subdue stubborn enemies. At present, a "noise bomb" has been developed, which can release a large number of noise waves between explosions, paralyze people's central nervous system and make people temporarily unconscious. This kind of bomb can be used against terrorists, especially hijackers.
(6) Using noise to diagnose diseases
As we all know, beautiful and melodious music can cure diseases. But how can noise be used for diagnosis? Recently, scientists have made a laser hearing diagnosis device, which consists of a light source, a noise generator and a computer tester. When in use, the micro-noise generator first produces weak and short noise to vibrate the eardrum, and then the microcomputer will display the data of the eardrum function according to the echo for the doctor to diagnose. It has the advantages of fast detection speed, no damage to eardrum and no pain, and is especially suitable for children. In addition, noise thermometry can also be used to detect human lesions.
(7) Active noise elimination.
Three commonly used noise reduction measures, namely noise reduction at sound source, noise reduction during propagation and noise reduction at human ear, are all passive. In order to actively eliminate noise, people invented the "active noise elimination" technology. Its principle is that all sounds are composed of a certain frequency spectrum. If a sound can be found, its spectrum is exactly the same as the noise to be eliminated, but its phase is just opposite (phase difference 180), and the noise can be completely eliminated. The key is how to get the noise-eliminated sound. The practical method is to start with the noise source itself and try to reverse the phase of the original noise through electronic circuits. From this point of view, active noise elimination technology is actually "fighting poison with poison".