Principle of noise-canceling headphones

In recent years, noise-cancelling earphones have gradually become high-end products in earphones. With the development and maturity of technology, active noise-cancelling has gradually been preferred by more people. However, active noise-cancelling is so good that its principle is known?

Active noise reduction technology

Two sinusoidal waves with the same frequency and amplitude, 180 degrees out of phase, will cancel each other out when superimposed. Using this principle can achieve the effect of noise cancellation. We often come into contact with the noise reduction headphones is to take this principle to achieve the effect of noise reduction. BOSE's ANC technology also uses this noise reduction principle. ANC technology uses a sound system to generate an audio signal with the same frequency and amplitude as engine noise, 180 degrees out of phase. When the noise signal and noise suppression signal overlap, they will cancel each other to achieve the effect of noise reduction.

Simple understanding is the spread of noise in the air, in the process of spread to the ear acoustic transmission, active noise reduction technology is to use a microphone to pick up acoustic noise, then used to simulate the operation unit, through the simulation of the same frequency sound waves to reverse the release, and in the air to the ear spread to counter the noise of the overlap, so as to dissipate spread to the ears of the noise, Realize noise reduction technology.

In the past two years, the most famous wireless Bluetooth noise-cancelling earphones are Apple's AirPods iii, whose powerful noise-cancelling function has attracted a large number of buyers. When you wear it on only one side, it doesn't cancel the noise. When you wear it on both sides, it immediately cancels out the noise even when no music is playing. I don't know if you, who like to immerse yourself in the world of music, are moved by such a product?