What is noise cancelling on a headset and how does it work?

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The world is full of different types of ambient sounds that make you feel alive, but they can also be a hindrance when they interfere with, or even block the sounds coming through your headset. To address this concern, many headsets and headphones are marketed with a noise cancellation feature, which seeks to reduce outside noise or block unwanted sounds, and allow you to focus on your conversation, music, or gaming.

How noise cancellation works

Noise cancelling headsets can be very helpful for getting things done wherever you are, and they typically come in two kinds: active and passive.

Passive noise reduction or noise isolation

Most decent models offer some degree of passive noise reduction owing to the materials used on the headphones themselves to block out specific sound waves, particularly those at higher frequencies. That said, there are certain models that offer superior passive noise-cancelling, such as the circumaural types, which feature special construction to optimise noise filtering properties.

These headphones are fabricated using multiple layers of a high-density sound-absorbing material, such as foam, which makes them slightly heavier than your typical headphones. But for the extra weight, users get to experience noise reduction of about 15 – 20 decibels (dB). Considering that jet engines emit 75-50 dB of noise within the cabin, passive models have a serious limitation.

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Active noise-cancelling

Headsets with active noise-cancelling offer the same barrier to high-frequency sound waves as passive models, though they have an extra level of noise reduction that involves actively erasing lower-frequency sound waves.

How exactly does this happen?

Active noise cancelling headsets use DSP – digital signal processing technology to actively cancel out low frequency sound waves from ambient noise. These headphones come with an audio processor and internal microphone that “listens” to sounds around you and play a contrasting sound to cancel it out, through a process known as destructive interference.

In other words, headsets with active noise-cancelling create their own sound waves that mimic the surrounding noise in every way, except for the fact that the headset’s sound waves are 180 degrees out-of-phase with the intruding sound waves, forcing them to cancel out.

How effective is noise cancellation?

Businessman struggling to hear his headsetHeadsets with active noise cancelling can effectively reduce overall noise by up to 80 dB, which means that a good set can handle constant, ambient noise, including jet engines, air conditioning, and conversation, though they cannot adequately adjust for sharp audio changes like a door slamming or someone shouting.

Noise cancelling headsets are great if you need to concentrate on your listening experience, or enjoy some peace and quiet, because you need to eliminate surrounding noise, though you should not use them if you need to listen to your surroundings for safety.

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