Noise Cancelling Headphones - The fundamentals of How They Block Unwanted Noise6675819

De GEATI - Grupo de Estudos Avançados em TI
Ir para: navegação, pesquisa

You will find basically two types of headphones designed to reduce background noise. Passive noise cancelling headphones and real time noise reduction. The passive type muffles extraneous sounds as the active ones electronically decrease external noise.


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


The active noise cancellation headphones produce an additional 20dB of noise reduction compared to the passive type. It employs the same technology (circum-aural sound dampening design) since the passive headphones but in addition incorporates phase cancellation. This is the key feature of active noise cancelling headphones. A microphone is put inside the headphone that picks up external noise how the aural cushions with the passive headphones cannot block out. The phase cancelling technology is able to analyze the intensity and frequency of the pitch, also known as the loudness and pitch with the noise. The circuitry then creates a perfect replica from 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" together with whatever it is that you will be listening to. This artificial noise is the exact opposite of the extraneous noise that makes it past the ear cushions. They then cancel one another out because of the 180-degree phase reversal. As a result the external noise is reduced significantly, allowing you to enjoy your audio having a dramatic reduction in background noise.

These kinds of headphones are fantastic for airplanes or anyplace where there quite a bit of external noise. On airplanes, for instance, this type of noise reduction with all the headphones will dramatically reduce fatigue.

Another distinction between the two is the active type needs a power source, usually a battery.

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