Noise reduction headphones are divided into active noise reduction and passive noise reduction. What is the principle of noise-canceling headphones? Headphone manufacturers and brand ear manufacturers will explain to you:
The principle of passive noise reduction headphones is naturally needless to say. By adding airtight materials such as sponge and rubber to isolate the ear canal from the outside world as much as possible, so as to reduce noise. But it is worth noting that this noise reduction method can effectively isolate high-frequency noise from the outside world, but the blocking effect of low-frequency noise is not obvious.
It is precisely because of various problems that passive noise reduction technology does not seem to be very satisfactory to many music enthusiasts, and active noise reduction headphones have emerged as the times require. Different from the passive type, the active noise-canceling headphones emit another kind of noise while blocking the external noise. The two kinds of noises neutralize each other, but achieve the purpose of noise reduction.
Active noise reduction headphones are active noise reduction, which generally add a battery (usually a rechargeable lithium battery or an AAA AAA battery) and a noise reduction circuit in the headphone line. Driven by the battery, the noise reduction circuit uses the built-in microphone to pick up the low-frequency noise in the environment (basically the sound between the frequency of 100~1000Hz), and manages to emit sound waves with the opposite phase of the noise and the same amplitude after the calculation. The positive and negative sound waves just cancel each other out, and the low-frequency noise magically disappears.