Noise Cancelling Headphones - The Basics of How They Block Unwanted Noise4693672
There are basically 2 kinds of headphones developed to reduce background noise. Passive noise cancelling headphones and app for noise cancelling. The passive type muffles extraneous sounds even though the active ones electronically decrease external noise.
Passive noise cancelling headsets use what is called circum-aural sound dampening design. They're shaped like just one cup, which surrounds the ear. The rim of the cup is made of a high-density foam and sound wave dampening material. This produces a seal that blocks up to 20 dB of noise.
The active noise cancellation headphones provide an additional 20dB of noise reduction compared to passive type. It employs exactly the same technology (circum-aural sound dampening design) because the passive headphones but in addition incorporates phase cancellation. This is actually the key feature of active noise cancelling headphones. A microphone is positioned inside the headphone that picks up external noise the aural cushions with the passive headphones can't block out. The phase cancelling technologies are able to analyze the intensity and frequency of the pitch, also referred to as the loudness and pitch from the noise. The circuitry then creates a precise replica of the noise and throws it 180 degrees out-of-phase. This, for all intents and purposes, eliminates the sound.
The headphone speaker then plays this "non-sound" along with whatever it is that you are listening to. This artificial noise may be the exact opposite with the extraneous noise that means it is past the ear cushions. They cancel one another 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 decline in background noise.
These types of headphones are fantastic for airplanes or any place where there is a lot of external noise. On airplanes, for instance, this type of noise reduction with all the headphones will dramatically reduce fatigue.
Another difference between the two is the active type requires a power source, often a battery.
Noise cancelling headphones are generally larger and heavier that regular headsets or earphones. They can, however, become more comfortable when worn for too long periods of time as a result of large cushions that impose less pressure on the ears.