What is the principle of active noise reduction headphones?

In the past, due to technological limitations, only earmuffs had active noise reduction function. But in the past few years, there have been significant breakthroughs in technology. Sony's WF-SP700N and WF-1000XM series of true wireless Bluetooth earphones were pioneers, and were later popularized by Apple's AirPods Pro. Now, true wireless Bluetooth earphones with active noise cancellation have become mainstream, and more and more brands are adding active noise cancellation to their products, allowing users to listen to music quietly without external interference.
Next, I will take you through all the doubts about noise cancelling headphones, and learn about the things to pay attention to when choosing true wireless noise cancelling headphones, as well as which ones currently on the market in 2022 have excellent noise cancelling effects and are worth recommending to everyone.
Noise cancelling true wireless Bluetooth earphones solve doubts
What is the principle of active noise reduction? Can all sounds be filtered?
Active noise cancelling headphones receive ambient noise through the microphone on the headphones (the microphone that receives voice during non call), and then use the internal chip of the headphones to generate reverse sound waves opposite to the noise to cancel out the ambient noise.
Active noise reduction technology works best in continuously noisy environments, such as the buzzing sound of aircraft, cars, or air conditioning engines. This mechanism eliminates the need to increase the volume to cover up external noise, while also helping users enjoy a moment of tranquility in noisy environments such as taking a plane or train.
However, although noise cancelling headphones can greatly reduce noise interference, they cannot completely block noise. Generally speaking, continuous low-frequency noise such as airplane engines or car engines is easier to filter out than high-frequency noise such as conversations or honking.
Does active noise reduction have an impact on sound quality?
When the headphones activate active noise cancellation, the speaker needs to play music while emitting reverse sound waves to counteract external noise, so the sound quality of the music will inevitably be affected. Therefore, most audiophiles prefer passive noise reduction over active noise reduction. But now the active noise reduction function can actually be turned on and off. Turning off noise reduction in a quiet environment can also provide a good listening experience and improve sound quality.
However, when listening to music in public transportation such as airplanes and trains, or in noisy places such as outdoors and offices, active noise reduction can actually help prevent interference from external noise. Therefore, if you are a audiophile who places great emphasis on sound quality, it is recommended to have both active noise cancelling headphones and high-quality headphones that can be used alternately in different places.
On the other hand, the technology of active noise reduction is also advancing, and its impact on sound quality is becoming smaller and smaller. For example, Ausound's AU Frequency ANC has Soundproof technology, which allows users to enjoy the same sound when noise reduction is turned on as when it is turned off.