ANC(Active Noise Cancellation): Reduce Unwanted Background Noise

Are you tired of the engine noise of vehicles on the way to work? Wanna get rid of whispering of colleagues at work? What you need is the earbuds with ANC technology.

As an incidental, annoying sound, noise has interrupted people’s daily life. In order to focus on work or enjoy pure music, people have devoted to lots of technical researches in the field of noise reduction headphones. Nowadays, there are two famous noise control technologies in noise-canceling. One is Passive Noise Control(PNC), another is what we will mainly discussed today: Active Noise Control(ANC).

Passive Noise Control(PNC)

The three noise reduction measures(canceling noise at the sound source/in the process of transmission/in the human ear), which are those conventionally used, are passive noise control. Passive Noise Control(PNC) means blocking the sound via the earphone shape design and using the internal filling material. However, this cancellation is aiming at the shielding effect of high frequency noise. When facing with low and medium-frequency noise, the PNC headphones are useless. Besides, when canceling the high frequency noise, it will also isolate the important part of human voice, which brings inconvenience to life.

What is ANC?

The Origin of ANC

In order to actively eliminate the noise and deal with low-frequency noise (such as people’s conversation, air conditioning noise, electrical engine noise, etc.), people invented the “active noise reduction” technology.

The concept of ANC was first proposed by Dr. Amar g. Bose, founder of Bose company. In 1989, Bose company launched the first ANC headset, which is specially designed for aviation industry practitioners. With the development of technology, ANC is gradually extending from high-end application to civil market.

The Principle of ANC

All sounds are composed of a certain spectrum. We can find a sound whose spectrum is exactly the same as the noise you want to eliminate. And the opposite phase can completely eliminate the noise.
Different from the traditional PNC, ANC technology generates a group of inverse sound waves with the same phase as the noise to be eliminated to neutralize the noise.
Active noise reduction headphones apply a highly sensitive acoustic microphone to collect the surrounding noise, and then use the built-in processor to calculate a sound wave which is completely opposite to the noise in real time to achieve noise cancellation.

The Specific Work Steps of ANC Earbuds:

1. The signal microphone installed in the earphone detects the low-frequency noise (100-1000HZ) (up to 3000hz at present)
2. Transmit the noise signal to the control circuit and perform real-time operation
3. The Hi-Fi horn emits sound waves with opposite phase and same amplitude to cancel the noise

The Logic of ANC

Pick-up Microphone(monitoring environmental noise) → Processing Chip (analyzing noise curve) → Loudspeaker (generating echo sound wave) → Completing the process of noise reduction synthesis.
In short, when the noise “A” is detected by an external pickup, the earbuds will instantly produce a sound “- A”. Two sound cancel each other in the ear. It can be said that the ear “heard” the noise, but also heard “noise reduction”, the two cancel each other in your ear to achieve noise reduction.

Three Types of ANC

Feedforward ANC: the microphone is exposed to noise and isolated from the speaker
Feedback ANC: place the microphone as close to the speaker as possible
Hybrid ANC: there are two microphones simultaneously, one is isolated from the speaker, the other is close to the speaker

Function of ANC

Reducing the low-frequency noise in the environment greatly, ANC allows you to feel the real “Silence”(only beautiful melody around the ear). Just sense the purest music experience in silence now.

The Application of ANC

Built for canceling regular environmental noise (such as the sound of people talking, the noise of air conditioning, the sound of electrical engine, etc.)

Suitable Crowd/Scenes

Business people, office workers, travel, work
Noise in the subway/cabin
Enjoy music, concentrate on work, relax

Advantages of ANCHeadset

Excellent performance, comfortable to wear.
Different from shielding all the sound, it makes appropriate noise reduction effect for environmental noise.
It plays an essential part in canceling medium and low frequency noise(such as the air conditioning noise, the noise of bus engine and the friction sound of subway engine, etc.,) and reducing the noise of 25db-35db at most.

Disadvantages of ANCHeadset

Expensive

BW and ANC TWS Earbuds

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This article is from BlitzWolf.