How Does the Microphone Noise Reduction Microphone Work?

PublishTime： 2022-02-10 Article Source：POROSVOC

At the beginning of the 20th century, microphones for noise reduction of microphones were developed into negative electric and capacitive conversion through resistance in the early stage, and many new microphone technologies were gradually developed, including microphones such as aluminum driving coils, and currently widely used condenser microphones and electret microphones. The working principle of the coil microphone is to use the human voice to vibrate the diaphragm through the air, and then use the solenoid on the diaphragm and the magnet surrounding the coil head to form a magnetic field cutting to form a weak wave current. The electrical current is passed through the loudspeaker, and the reverse process converts the wave-current into sound.In this paper POROSVOC will tell you How does the microphone noise reduction microphone work?

Fig.1

Ribbon Microphone

For ribbon microphones, the ribbon used is the conductor that moves in the microphone membrane and magnetic field. The aluminum strip is generally made of aluminum wire, with a thickness of 0 to 1 mm, a width of 2 mm to 4 mm, and a mass of only 0.2 mg, which can obtain a better transient response. In order to obtain the ideal resonant frequency between 2kHz~4kHz, the aluminum strip is pleated to maintain the correct tension value. The aluminum strip is a conductor and a microphone membrane. It hangs in the magnetic field between the two pole faces and vibrates according to the frequency of the incident sound wave, generating a certain voltage output at both ends of the aluminum strip.

Capacitor type

The condenser microphone for microphone noise reduction has two metal plates, one of which is coated with the main body film (mostly Teflon propylene) and grounded, and the other plate is connected to the gate of the field-effect transistor, and the pole is connected to the gate of the field-effect transistor. A diode is connected between the chip and the monopole. If the electret diaphragm itself has a charge, the power of the surface charge is Q, and the battery capacity between the plates is C, then the pole head generates a ground voltage U=Q/C. When it is rubbed by vibration or airflow, the vibration will cause the two poles The distance between the plates changes, that is, the capacitor C changes, if the electric q does not change, the voltage changes, and the magnitude of the voltage change.

The membrane film of the condenser microphone for microphone noise reduction is mostly made of PTFE, which has good humidity performance, more surface charge, and little impact of humidity. Because this miniature mobile phone is also a capacitive structure, the internal resistance of the signal is very large. In order to draw out the voltage signal generated by the sound and amplify it, the output end must also use a field-effect transistor.

history

The history of microphones can be traced back to the end of the 19th century. Scientists such as Alexander Graham Bell worked hard to find ways to better select sounds in order to improve the latest invention at the time, the telephone. During this time they invented liquid microphones and carbon microphones, which were not very effective and could only be used grudgingly.

In 1949, Berner Bast Laboratories (the predecessor of Sennheiser) developed an MD4-type microphone that suppressed sound in loud environments and reduced background noise. This is the world's first noise-canceling microphone that suppresses feedback. At the 1961 Messe in Hannover, Germany, Sennheiser displayed the MK102 and MK103 microphones.

These two microphones use a new microphone manufacturing concept - RF RF condenser, that is, a small and thin diaphragm, which ensures small, lightweight, and excellent sound quality. In addition, this microphone is very sensitive to electromagnetic interference. The impact on climate has strong anti-interference performance. It is used by expedition teams and works in the field day and night. The temperature difference is large. In the face of harsh field conditions, the microphone is still outstanding.

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