How Does Noise Cancellation Work?

As strange as this might sound, noise cancelling technology came about due to the needs of American military. In 1978 the U.S. government wanted to create a new type of headphones that would allow aircraft pilots and NASA astronauts to communicate clearly with ground crews even with the sound of a plane or rocket’s engines on at full blast.

This was a tall order back then, but this technology eventually trickled down into consumer grade electronics used by the general public. Today, we call it Active Noise Cancelling technology (ANC). But what is the difference between Active Noise Cancelling (ANC) and Passive Noise Cancelling (PNC) tech?

Well, sound travels in waves. A similar example of this would be the propagation of the waves of an ocean. These waves need a medium such as air, water or solid objects to travel from on place, to another. Since space is a massive void of emptiness there’s no medium to speak of. And that is why an explosion can happen in space, but we wouldn’t hear it.

Here on earth, we are able to hear all manner of sound due to the air around us. It acts as a medium, with which sound waves can propagate around us. Sound waves are made up of peaks (highest points) and troughs (lowest points). ANC technology in your headphones basically emit equal but opposing waves of that produced by ambient sounds around you.

Think about it this way. When you tap your finger in a bowl of water, you create successive water waves that travel outwards in every direction. Now, if you were to place one finger at one end of the bowl and another on the opposing side, and with the same amount of force but at different intervals, tap the surface of the water, you’re observing the basic principle of ANC.

The waves that are created by your fingers, propagate towards and toward each other. But, once they meet in the middle and collide (provided that you’ve used the same amount of force), they disappear. The same is true for ANC. Your headphones/ earphones’ mics pick up ambient sounds around you, analyze them, then return opposing waves to cancel them out.

However, the technology isn’t perfect because ANC tech needs time to analyze and respond to these waves as quickly as possible. In addition to this, it’s better at responding to low frequency waves than higher ones. Once ANC has learned a particular sound, it commits it to memory. And once the mics pick up the same sound again, ANC is able to respond at a quicker rate.

That is why ANC is better at blocking out regular ambient noises at an airport or train station than chatty colleagues with no semblance of self awareness. The tech can isolate you from all these sounds, but it’s just more effective at certain ones. And how successful it is, depends entirely on the headphones’ hardware.

Passive Noise Cancelling (PNC), is a rudimentary type of technology that doesn’t involve electronics. The principle behind it, is to seal your ears off from the air around you. The foam from the ear tips or its size relative to that of your ear canal, help to prevent the air from entering your ears. This in turn, prevents ambient sound from reaching you or ruining your music.

Both ANC and PNC have their advantages and drawbacks. However, when paired together they’re able to minimize each other’s faults and in turn, provide you with a decent amount of sound isolation. As such, when picking up a pair of wireless headphones or earphones, remember to check which one of these two types of technology it offers.

Source: Samsung Mobile Press