It is well known that Bluetooth headsets are mainly divided into passive noise canceling and active noise canceling in terms of noise canceling. Most of the methods on the market are passive noise canceling. Beginning in 2021 should be the market for active noise canceling, that is, the trend of ANC noise canceling headset, so Bluetooth headset factory will elaborate on the principle of ANC noise canceling headset today, so that everyone can better understand ANC active noise canceling headset.
Active noise canceling can generally be subdivided into Feedforward ANC (feedforward active noise canceling), Feedback ANC (feedback active noise reduction) and Hybrid ANC (hybrid active noise reduction, in fact, feedforward plus feedback). Each of these methods can be divided into adaptive (adaptive) and non-adaptive (non-adaptive) ANC. Generally speaking, adaptive ANC can only be digital control. However, under non-adaptive ANC, it can be divided into analog (analog) and digital ANC. A long time ago, because the DSP chip was not powerful and did not support real-time complex calculations, etc., there were only analog ANC headsets on the market, which used capacitors, inductors, resistors and other components to implement the calculated ANC controller. Now with the rapid development of DSP chips, ANC controllers can be digitized. There are many advantages, such as the intensity of ANC can be adjusted, etc., some earphones, noise reduction ability can be controlled by mobile phone APP. At present, it is basically the world of digital ANC headsets on the market.
Principle of active noise canceling:
Active noise canceling headset are much more complicated than ordinary headset. A noise reduction module needs to be built into the headphones. It contains a microphone to receive external noise. After calculation by the internal circuit, it is added and added while the headset are playing music. The sound wave of the "inverse" of the external noise, thereby canceling the external noise.
Here we mainly talk about active noise canceling. Active noise canceling is divided into three types of noise reduction: feedforward noise reduction, feedback noise reduction, and a combination of feedforward and feedback. Feedforward and feedback noise canceling Feedforward noise reduction is to design the microphone on the outside of the earphone away from the speaker, while feedback noise reduction is to design the microphone near the speaker. Feedforward noise reduction is easier to achieve, while feedback noise canceling can collect noise information closer to what the human ear hears. However, the microphone may be affected by the sound of the speaker, which requires higher algorithms.
At present, the relatively high-end noise canceling headset mostly combine the design of passive noise reduction, feedforward and feedback noise reduction, which has a very good effect on noise shielding and elimination.
Due to the complex structure and working principle of active noise reduction headphones, the price is generally much higher, most of which are in the price range of 1,000 yuan or more. However, the shortcomings of active noise reduction headphones are also obvious. Because the sound unit will additionally emit sound waves that cancel the noise, there will still be differences in sound quality and sound details will be lost.
However, with the development of Bluetooth headset factory technology, the current active noise reduction headsets also have quite good sound quality performance, and the applicability is broader than passive noise reduction. Although this technology has been developed for decades, it still has a lot of room for improvement. If you have the conditions, it is better to choose active noise-cancelling headset.