[introduction]Fast rhythm has been the normal that everybody lives, the office environment of open mode, commute diligent on the road, in journey bussiness trip… our all the time is not being affected by noise pollution. Then the development as science and technology, earphone looks at very common device this, already from most begin to satisfy the requirement that can listen, fall to now what a confusion of voices becomes a lot of office worker is firm need. We want to have an earphone, help us escape the interference of noise, seek oneself independent space, the music that seeks listen respectfully is more real, but do you understand really ” fall a confusion of voices ” ? What often hear is active fall earphone of a confusion of voices, what is working principle?  

Fast rhythm has been the normal that everybody lives, the office environment of open mode, commute diligent on the road, in journey bussiness trip… our all the time is not being affected by noise pollution. Then the development as science and technology, earphone looks at very common device this, already from most begin to satisfy the requirement that can listen, fall to now what a confusion of voices becomes a lot of office worker is firm need. We want to have an earphone, help us escape the interference of noise, seek oneself independent space, the music that seeks listen respectfully is more real, but do you understand really ” fall a confusion of voices ” ? What often hear is active fall earphone of a confusion of voices, what is working principle?
 
Actually, fall a confusion of voices earphone manufacturer does not advance this idea first. Be in early 1933, one those who call PaulLueg is German, put forward to fall actively the academic principle of technology of a confusion of voices, filed patent: Through using loudhailer and microphone, make sound wave gets the influence of opposite sound wave, will eliminate noise.
 
We know sound is a kind of wave, simple for namely, when the wave that delivers when two opposite way encounters, hand in in the wave crest of a wave and another trough of wave collect place, both will offset each other. Then, two audio overlay is in theoretic can form breathed. This is just like Russia diamonds same, sunken model noise, the protruding that earphone gives out a semmetry, both overlay rises to be able to be eliminated. This concept was established fall the base of earphone of a confusion of voices develops way, affect up to now.
 
Understanding is over fall after the origin of earphone of a confusion of voices, we come again specific understanding drops the principle of a confusion of voices. Fall earphone of a confusion of voices from fall the implementation of a confusion of voices is divided on means to fall actively a confusion of voices and passivity fall a confusion of voices two kinds, and we say fall of earphone of a confusion of voices fall function of a confusion of voices, point to more fall actively a confusion of voices.  Should say to be clear about fall actively a confusion of voices, what we understand first is passivity falls a confusion of voices. Passivity falls cost of earphone of a confusion of voices is inferior, one kind be the easiest implementation falls technology of a confusion of voices, can imagine in noisy environment, cover with both hands auditive behavior, this similar passivity falls a confusion of voices. Its principle is to use character of physics of passive parts of an apparatus to rise to fall effect of sound insulation of a confusion of voices, if Dai Pi of cap of silica gel ear, head is covered,wait. This method is very simple and rough, difficulty is to depend on choosing the acoustics material that has drawn to make ear-muff, earplug, and reduce leakage sound. So passivity falls what a confusion of voices can reduce 15-25 decibel only commonly is medium high frequency noise, and low frequency noise still can enter ear through aperture, produce sound resonance.

And fall actively the process of a confusion of voices is roughly such, above all environmental noise is fallen microphone of a confusion of voices is collected, repass falls actively after chip of a confusion of voices is handled, generate one retrorse the sound wave with 180 phasic ° , spread person ear way through earphone loudhailer, produce phasic difference with noise 180 ° , the environmental noise that offsets person ear should be heard originally, achieve thereby fall the purpose of a confusion of voices. According to falling actively the working principle of earphone of a confusion of voices reachs design construction, can fall the make a present of before its fractionize is actively, feedback falls actively a confusion of voices and mix to fall actively a confusion of voices 3 kinds, and no matter which kinds included a microphone and sub sound source.

Microphone is in charge of collecting noise, the part is complex of type fall actively earphone of a confusion of voices still can have two microphone, one is used at collecting exterior noise, microphone of the reference that be called, another is used at collecting in-house noise, microphone of the error that be called. Sub sound source basically is the loudhailer that points to all sorts of types, it basically is sound of electric energy translate into and can go to of sound energy radiate.

To before type of make a present of, its noise collects microphone to compare loudhailer of sub sound source more rely on to be bordering on noise source. This kind of signal that controls a construction handles a process to be: Buy microphone collect consults outside noise signal, send DSP interior to undertake accommodative oneself handling next, get used to what processing generates to turn over photograph noise to be given out via sub sound source oneself; And to feedback type, its noise collects microphone to compare loudhailer of sub sound source more rely on to be bordering on person ear. This kind of signal that controls a construction handles a process to be: The turns over photograph noise mixture noise signal that the primitive noise that buy microphone collect enters earphone interior inside and sub sound source issue, send DSP interior to undertake accommodative oneself handling next, get used to what processing generates to turn over photograph noise to be given out via sub sound source again oneself; And Composite is before an overlay of make a present of and feedback, this kinds command the advantage of the make a present of before the system was united in wedlock and feedback, the meeting with its inevitable system becomes very complex.

Before type of make a present of (left) with feedback type (right) plan of ANC earphone structure  Although active fall the principle of a confusion of voices looks be like simple, but can be faced with in producing a course actually a series of problem, for instance the processing of wind a confusion of voices, fall the negative pressure effect of earphone of a confusion of voices, broadcast musical hourglass sound to be fallen collect of MIC of a confusion of voices, fall a confusion of voices is optimized algorithmicly wait for a problem, wanting to had been done so is very difficult actually, this also is market on top class active fall earphone of a confusion of voices betrays so noble cause.

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