ancActive noise reduction is a kind of noise reduction technology. It is one of the methods of noise reduction used in headphones. There are three noise reduction measures commonly used to reduce noise, namely noise reduction at the sound source and noise reduction at the source. Noise reduction during the process and at the human ear is passive.
#The operating environment of this article: Windows 7 system, Dell G3 computer.
Active noise reduction is a kind of noise reduction technology and one of the methods used in headphones to reduce noise.
The three noise reduction measures commonly used to reduce noise, namely noise reduction at the sound source, noise reduction during the propagation process and noise reduction at the human ear, are all passive. In order to actively eliminate noise, people invented the technology of "active noise cancellation". Its principle is: all sounds are composed of a certain spectrum. If you can find a sound whose spectrum is exactly the same as the noise to be eliminated, but the phase is exactly opposite (180° difference), the noise can be completely canceled out. . The key is how to get the sound that cancels out the noise. The actual approach 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, the active noise reduction technology is actually "fighting fire with fire."
Sound is produced by the vibration of objects, and the form of vibration propagation in elastic media is sound waves. Sound waves in a certain frequency range (20~20000Hz) act on the human ear to produce the feeling of sound. Noise is usually defined as "unwanted sound" and is an environmental phenomenon. People are exposed to noisy environments throughout their lives, and noise is also an environmental pollutant produced by various human activities. Vibration is the reciprocating periodic motion of an object (or part of an object) along a straight line or curve and passing through an equilibrium position. It exists widely in nature and engineering circles.
Since vibration is the source of noise, in the practice of vibration reduction and noise reduction, noise problems can be effectively solved by solving vibration. In common noise control, thin metal plates vibrate. For example, the tube walls of aerodynamic machinery, machine shells, car bodies, and ship hulls are generally made of thin metal plates. When the equipment is running, these thin plates will vibrate and radiate noise. , such noise caused by the vibration of metal plate structures is called structural noise. For effective control methods of this kind of metal plate radiation noise, the first is to minimize the noise radiation area in the design and remove unnecessary metal plate surfaces; the second is to apply a layer of damping paint on the metal structure and use damping materials to suppress Structural vibration and noise reduction are called vibration damping, which is an active noise reduction technology.
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