Classification Of Noise Reduction Earphones

There are two methods for noise reduction of earphones, active noise reduction and passive noise reduction.

The active noise reduction function is to neutralize the noise by generating inverted sound waves equal to the external noise through the noise reduction system, so as to achieve the effect of noise reduction. The active noise reduction earphones are equipped with noise reduction circuits that compete with the external noise. Most of them are of large head mounted design. They can use earplug cotton and earphone shell to block the external noise for the first round of sound insulation. At the same time, in order to have enough space to install the active noise reduction circuit and power supply.

Passive noise reduction earphones mainly form a closed space around the ear, or use sound insulation materials such as silicone earplugs to block external noise. Since the noise is not processed by the noise reduction circuit chip, it can only block high-frequency noise, and the noise reduction effect on low-frequency noise is not obvious.

The three noise reduction measures commonly used to reduce noise, namely, noise reduction at the sound source, noise reduction in the propagation process and noise reduction at the human ear, are all passive. In order to actively eliminate noise, people invented the technology of "active noise elimination". Its principle is that all the sounds heard are sound waves with a certain frequency spectrum. If a sound wave can be found, its spectrum is equal to the amplitude of the noise to be eliminated, and its phase is just opposite (180 °), and the noise can be completely canceled by superposition of the two. The key is how to get the noise canceling sound. The actual method is to start with the noise itself, use the microphone to monitor the noise, and then try to generate a reverse sound wave through the electronic circuit and play it through the speaker. From this, it can be seen that the technology of active silencing is actually "attacking poison with poison".

When dealing with complex noise environment, the two MEMS microphones of "active noise reduction" will respectively pick up in ear noise and various external environment noise. They are equipped with an independent intelligent HD noise reduction processor to perform high-speed calculation on the picked up different noises and accurately eliminate noise. And for the noise reduction needs of different scenes, the headset provides a variety of listening modes: strong and weak active noise reduction modes and an ambient sound mode. Isolate the external noise to different degrees, and eliminate the "black hole feeling" of common noise reduction earphones when listening.