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Three-minute little science: What is the difference between single-feed noise reduction and hybrid noise reduction?

Just two days ago, an unnamed friend of mine asked me a question, he said that when purchasing noise-canceling true wireless headphones, the product detail page will write what feed-forward active noise reduction, one will write hybrid active noise reduction, what is the difference between these noise reduction modes? I see that this is a very good question, very suitable for taking it out alone to explain what is single-feed noise reduction? What is hybrid active noise cancellation?

Three-minute little science: What is the difference between single-feed noise reduction and hybrid noise reduction?

Diagram

Now in daily life is full of all kinds of noise, in order to avoid the trouble of noise, active noise reduction headphones have been introduced. Active noise reduction should be very well understood, this is a technology applied to the noise reduction headphones, which collects ambient noise through the pickup microphone above the headphones, converts the noise collected by the microphone into a digital signal, and calculates a sound wave opposite to the noise through the built-in processor and algorithm, thus eliminating the effect of noise.

But now there are many small partners in the purchase of active noise reduction headphones, look at the introduction in the product details page will look like a dizzy, one will write that this headset supports feed-forward active noise reduction, one will write that the use of feed-back active noise reduction, one will be more expensive headphones and write support hybrid active noise reduction, it is very confusing. In fact, before 2019, most products of active noise reduction headphones used single-feed active noise reduction. In the second half of 2019, Hybird hybrid active noise reduction technology began to be applied in headphone products. Now that you've learned the basics, you need to look at what single-feed noise reduction and hybrid active noise reduction are.

Three-minute little science: What is the difference between single-feed noise reduction and hybrid noise reduction?

Most of the things that are not mentioned are single-feed noise reduction

Feed-forward active noise reduction

Let's start with feed-forward active noise reduction. In the early days, most of the low-cost active noise cancellation headphones used feed-forward active noise cancellation, because its structure is very simple, only need to configure a microphone on the outside of the two headphones to detect the surrounding ambient noise. This scheme ensures that the sound emitted by the headphone speakers does not interfere with the microphone that picks up the noise. This noise reduction scheme is very direct, after the microphone collects the noise signal, the processor directly processes it, and the headphone speaker emits reverse sound waves to neutralize the noise. This is a relatively simple, low-cost noise reduction scheme, some sudden noise can not be well filtered, there will be noise that can not be filtered in time to the ears.

Feedback active noise reduction

Feedback active noise reduction and feed-forward active noise reduction are both single-feed noise reduction structures. Feedback active noise reduction places the microphone that collects noise near the headphone speaker, and the noise collected by the feedback active noise reduction scheme is closer to the sound that can be heard by the human ear. This results in slightly better noise reduction than the feed-forward. However, the disadvantages of feedback active noise reduction are also very obvious, and it is easy to appear high-frequency acoustic noise. At the same time, music sounds similar to noise are treated as noise, which will cause a certain degree of music distortion

Three-minute little science: What is the difference between single-feed noise reduction and hybrid noise reduction?

Hybrid noise reduction is basically clearly stated

Hybird hybrid active noise cancellation

Hybird Hybrid Active Noise Cancellation, on the other hand, uses two or more microphones for noise monitoring, but these microphones are not meant to allow them to listen to external noise at the same time, because if they all listen for external noise, it will bring 1+1<2 effect. Doubling the number of microphones brings additional power consumption and data operations and a 1+1<2 negative power consumption increase, which is definitely not worth it. Hybrid active noise cancellation is to arrange multiple microphones outside the headset and near the speakers, one part for feed-forward noise reduction, and part for feedback-back noise reduction. Feed-forward microphones monitor ambient noise just like single-feed noise-cancelling microphones, while feed-back microphones monitor filtered noise that can also be transmitted into the ear. The two systems work together for noise cancellation, combining the advantages and disadvantages of the two, making the Hybird hybrid active noise cancellation allow the headphones to achieve a deeper noise reduction effect. Of course, this set of technologies also has shortcomings, one is that the design is difficult to achieve, and the other is that it will bring higher costs.

Basically, the active noise reduction technology we can see on the market is the three mentioned above. However, in recent years, single-feed active noise cancellation headphones are being eliminated by the times, and only single-feed active noise reduction can be seen on some lower-end products. Finally, to give you a little advice, if you want to get better noise reduction, hybrid active noise reduction is always the first choice, and in general, more expensive headphones can have better noise reduction.

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