Просмотр исходного текста страницы Noise Cancelling Headphones - The basic principles of How They Block Unwanted Noise1914477

You will find basically two kinds of headphones created to reduce background noise. Passive noise cancelling headphones and [http://owp.valuesv.jp/wiki/index.php?title=Noise_Cancelling_Headphones_-_The_fundamentals_of_How_They_Block_Unwanted_Noise3173532 background noise reduction]. The passive type muffles extraneous sounds as the active ones electronically decrease external noise.


Passive-

Passive noise cancelling headsets use what is called circum-aural sound dampening design. They're shaped like a cup, which surrounds the ear. The rim with this cup is made of a high-density foam and sound wave dampening material. This results in a seal that blocks approximately 20 dB of noise.

Active-

The active noise cancellation headphones produce an additional 20dB of noise reduction compared to passive type. It employs the same technology (circum-aural sound dampening design) because the passive headphones but also incorporates phase cancellation. Here is the key feature of active noise cancelling headphones. A microphone is put inside the headphone that accumulates external noise the aural cushions of the passive headphones can't block out. The phase cancelling technology is able to analyze the intensity and frequency of the pitch, also referred to as the loudness and pitch with the noise. The circuitry then creates a precise replica of the noise and throws it 180 degrees out-of-phase. This, for those intents and purposes, eliminates the sound.

The headphone speaker then plays this "non-sound" in addition to whatever it is that you are listening to. This artificial noise is the exact opposite of the extraneous noise that makes it past the ear cushions. They then cancel each other out due to the 180-degree phase reversal. Because of this the external noise is reduced significantly, allowing you to enjoy your audio using a dramatic decrease in background noise.

These kinds of headphones are fantastic for airplanes or anyplace where there quite a bit of external noise. On airplanes, for example, this type of noise reduction while using headphones will dramatically reduce fatigue.

Another difference between the two would be that the active type takes a power source, normally a battery.

Noise cancelling headphones are generally larger and heavier that regular headsets or earphones. They can, however, be a little more comfortable when worn for very long periods of time due to the large cushions that impose less pressure about the ears.