Microphone Noise Cancelling: How Do Noise-cancelling Microphones Work?

PublishTime： 2022-02-13 Article Source：POROSVOC

Microphone noise reduction is a microphone that uses directional processing of sound signals to improve the signal-to-noise ratio, so that users can hear the words of the opposite person when there is background noise.This article POROSVOC will introduce How Do Noise-cancelling Microphones Work?

The history of microphone noise reduction can be traced back to the end of the 19th century. Scientists like Alexander Graham Bell worked hard to find better ways to select sounds in order to improve the then-new invention of the 3354 telephone. Previously, they had invented liquid microphones and carbon microphones, which didn't work well and could only be used grudgingly.

In 1949, Bene Bast Laboratories (predecessor of Sennheiser) developed the MD4-type microphone, which suppressed sound in loud environments and reduced background noise. This is the world's most feedback-suppressing noise-cancelling microphone.

At the Industrial Fair in Hannover, Germany in 1961, Sennheiser displayed the MK102 and MK103 microphones. These two microphones use the new microphone manufacturing concept 3354RF RF condenser type, that is, a small and thin diaphragm, ensuring small, light and high sound quality. Also, this microphone is very sensitive to electromagnetic interference. The impact on the climate is that it has strong anti-interference performance. It is used by expedition teams, working in the field day and night, and the temperature difference is large. In the face of harsh field conditions, the microphone is still outstanding.

How does microphone noise reduction work?

The microphone noise reduction is transmitted from the vibration of the sound to the diaphragm of the microphone, which pushes the magnet inside to form a changing current, so the changing current is transmitted to the sound processing circuit behind, expanding.

Sound is a wonderful thing. All the sounds we hear are caused by subtle pressure drops in the air around us. The amazing thing is that the air can transmit these differential pressures so completely, so realistically, over considerable distances.

It is attached to a needle with a metal septum, and this needle scratches the pattern on the metal foil. When you speak into the diaphragm, the air pressure difference that occurs causes the diaphragm to move, causing the needle to move, and the movement of the needle is recorded on the foil. Then, the needle is turned back on the foil, and the vibration of the scratch on the foil will move the diaphragm and the sound reproduces. The operation of this purely mechanical system shows how much energy can be generated by vibrations in the air!

All modern Mikes do exactly what the first Mike was supposed to do. Just use electricity instead of mechanical. The microphone converts fluctuating pressure waves in the air into fluctuating electrical signals. There are five common techniques to accomplish this conversion.

folded carbon

Old, simple microphone, using carbon dust. This technique was historically used in telephones and is still used in some telephones today. The carbon dust has a thin metal or plastic film on one side. When sound waves hit the diaphragm, they compress the carbon dust, changing resistance. By supplying electricity to the carbon, the changed resistance can change the magnitude of the current. See How Phones Work for details. folding mechanics.

Dynamic microphones utilize electromagnetic effects. When the magnet is passed through the wire (or coil), the magnet senses the current in the wire. On a dynamic microphone, when a sound wave hits the diaphragm, the diaphragm moves the magnet, and this movement produces a small electrical current.

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