What Are the Classifications of Microphones for Microphone Noise Reduction?

PublishTime： 2022-02-11 Article Source：POROSVOC

Microphone noise reduction, translated from the English microphone (microphone), also called a microphone. A microphone is an energy conversion device that converts sound signals into electrical signals. Categories include actuators, condensers, electrets, recently emerging silicon microphones, liquid microphones, laser microphones, and more. Most microphones are electret condenser microphones, which work by utilizing a polymer diaphragm with permanent charge isolation.Here POROSVOC will tell you what are the classifications of microphones for microphone noise reduction?

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What are the classifications of microphones for microphone noise reduction?

According to the principle of energy exchange, microphones can be divided into two types: electric microphones and condenser microphones. Among them, the current can also be subdivided into homotopy microphone and aluminum ribbon micro.

Microphone noise reduction Typical commercial microphone types include condenser microphones, crystal microphones, carbon microphones, and dynamic microphones. Commonly used condenser microphones use two energy sources: DC bias power and electret film. Both condenser and crystal microphones convert acoustic energy into electrical energy, which creates a changing electric field. Carbon microphones use a DC voltage source to change resistance through sound vibrations, converting the sound signal into an electrical signal.

Condenser, crystal, and carbon microphones generate a voltage signal proportional to the displacement of the sensitive membrane, while dynamic microphones generate a voltage signal proportional to the vibration velocity of the sensitive membrane. Dynamic microphones use permanent magnets as an energy source to convert sound energy into electrical energy based on an inductive effect.

What are the microphone characteristics of microphone noise reduction?

Most microphones are electret condenser microphones (ECM), used for decades. ECM works by utilizing a polymer diaphragm with permanent charge isolation. The MEMS microphone is not affected by temperature, vibration, humidity, and time, and is compared with the polymer material diaphragm of ECM at different temperatures. Due to their strong heat resistance, MEMS microphones can withstand high-temperature reflow soldering at 260°C without changing performance. There is less variation in sensitivity before and after assembly, so audio tuning costs can also be reduced during manufacturing.

At present, integrated circuit technology is more and more widely used in the manufacture of sensors and sensor interface integrated circuits. The micro-fabrication process has the advantages of precise, flexible design, miniaturized size, integration with signal processing circuits, low cost, and mass production. The research results show that the early miniature microphones are based on the piezoresistive effect, and the microphones with (11)cm2, 2m thick polysilicon film as the sensitive film are made.

However, in the absence of stress in the sensitive film, the first resonance frequency of such a large and thin polysilicon film will be below 300 Hz. In a frequency range with such a low first resonant frequency, the frequency response in the audible frequency range of the microphone may become very non-uniform (variation in sensitivity by more than 40 dB) and is therefore unacceptable for microphone applications. When the sensitive film is under tensile stress, the resonance frequency increases, but at the expense of sensitivity.

Of course, by adjusting the size of the sensitive film, a higher first resonance frequency can be obtained, but the sensitivity will still be reduced. It can be seen that the pressing scheme is not suitable for the manufacture of miniature microphones.

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