Headphones and earphones that feature active noise reduction (ANR) use noise cancellation technology. How is noise cancellation and how it works?
To familiar with the noise cancellation technology, we should first know what sound is. We cannot notice sound by our eyes. If we draw out the noise, it is similar to a wave. In facts, the noise you hear is the compression and decompression of the particles while we are talking. The moving particles will have tiny changes because of the air pressure. The power of these changes in air pressure is called amplitude. The louder the sound, the more extreme the amplitude. Therefore, the picture will show the wave to represent the sound movement.
How to cancel the noise outside the earphones?
As mentioned before, the sound is similar to waves. For noise cancellation, it just likes producing a sound wave which is the mirror image of a noise that is undesired. Then, the sound energy will eliminate form the environment. Then, you will not hear the wanted sound.