Noise Cancelling Headphones - The basic principles of How They Block Unwanted Noise7758167

There are basically two kinds of headphones created to reduce background noise. Passive noise cancelling headphones and Mute Background Noise. The passive type muffles extraneous sounds even though the active ones electronically decrease external noise.

Passive-

Passive noise cancelling headsets use what is known as circum-aural sound dampening design. They are shaped like just one cup, which surrounds the ear. The rim of the cup is constructed of a high-density foam and sound wave dampening material. This results in a seal that blocks as much as 20 dB of noise.

Active-

The active noise cancellation headphones provide an additional 20dB of noise reduction compared to the passive type. It employs the identical technology (circum-aural sound dampening design) as the passive headphones but also incorporates phase cancellation. This is actually the key feature of active noise cancelling headphones. A microphone is put inside the headphone that accumulates external noise the aural cushions from the passive headphones cannot block out. The phase cancelling technologies are able to analyze the intensity and frequency from the pitch, also called the loudness and pitch from the noise. The circuitry then creates an exact 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" together with whatever it is that you are listening to. This artificial noise is the exact opposite of the extraneous noise that means it is past the ear cushions. They then cancel each other out because of the 180-degree phase reversal. Because of this the external noise is reduced significantly, allowing you to enjoy your audio with a dramatic reduction in background noise.

These types of headphones are fantastic for airplanes or anywhere 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, usually a battery.

Noise cancelling headphones tend to be larger and heavier that regular headsets or earphones. They can, however, become more comfortable when worn for long periods of time as a result of large cushions that impose less pressure on the ears.