The Foundation of Sound Transmission: Principle of Disassembling Microphone, Selection Logic and Global Industry Application

Microphone, the industry name microphone, is the most basic acoustic-electrical conversion device in the audio industry chain. Simply put, its core value is to transform air sound waves that can be perceived by human ears into electrical signals that can be transmitted, recorded and digitally processed. As the first entrance equipment for audio acquisition, the microphone is connected with acoustic physics, audio algorithm and signal transmission technology. It is not only a common radio tool for live broadcast and recording, but also an indispensable basic hardware in the fields of consumer electronics, intelligent manufacturing, artificial intelligence and radio and television communication.
First, the basic working principle
Regardless of the category, price and use, the radio logic of all microphones is highly consistent. The sound source stirs the air to form sound waves, which hit the precision diaphragm inside the equipment and drive the diaphragm to generate subtle vibration; The internal transducer module captures the vibration change and synchronously converts it into a fluctuating electrical signal to complete the acoustic-electrical conversion. The volume of the sound source determines the vibration amplitude of the diaphragm; The pitch determines the vibration speed. As long as the performance of the device is stable, the output electrical signal can be 100% restored to the original sound, ensuring the authenticity of the radio.
It should be noted that the intensity of the electrical signal originally output by the microphone is extremely low, and the transmission process is extremely prone to loss and distortion. Therefore, whether it is a professional recording device or a built-in radio module in a mobile phone or earphone, it is necessary to complete signal amplification with a sound card and a preamplifier to make up the transmission loss, which is also the core reason why an audio device must be equipped with a gain module.

Second, the classification of mainstream categories and their advantages and disadvantages
There are many kinds of commercial microphones in the market, and the difference in appearance and price is wide. The industry is generally divided into two categories according to the principle of transducer. The applicable scenes, thresholds and radio characteristics of the two have their own advantages and disadvantages. There is no universal model, and the industry selection is always matched as needed.
(1) Moving coil microphone
Moving coil microphone works on the principle of electromagnetic induction, and its internal structure consists of diaphragm, voice coil and permanent magnet. Sound waves push the diaphragm to drive the voice coil to move, cutting the magnetic field to generate electrical signals. The whole structure is sturdy and durable, with excellent anti-falling, dustproof and moisture-proof performance, strong anti-external noise ability and stable working condition. The shortcomings are that the sensitivity of radio reception is low, and the reproduction of high-frequency details is weak, so it is difficult to capture subtle sound sources such as light tone and air sound. At present, it is mostly used in outdoor interviews, stage performances, on-site sound reinforcement and other high-noise environments, and it is also the mainstream style of commercial handheld microphones.
(2) Capacitive microphone
The condenser microphone completes the radio reception by changing the capacitance of the polar plate, and the internal diaphragm acts as a variable capacitance polar plate, and the sound wave vibration changes the distance between polar plates, thus generating an electrical signal. This microphone has high radio sensitivity, wide frequency response range, excellent vocal texture and excellent tone color detail reproduction, and is the first choice for professional audio recording. The short board has a precise internal circuit, which is poor in earthquake resistance and moisture resistance. Most professional models need external power supply. Daily life is divided into large diaphragm condenser microphone and electret microphone: the former is specially designed for recording studio and film dubbing; The latter is small in size and controllable in cost, and is widely used in consumer electronic products such as mobile phones, Bluetooth headsets and collar-clip microphones.
Third, the easily overlooked core acoustic parameters
Whether it is enterprise procurement, project selection or personal purchase, most people tend to put the cart before the horse, give priority to appearance and price, and ignore the core parameters that determine the quality of radio, which eventually leads to many problems such as noise, voice distortion and radio deviation. Three of these parameters are the core yardsticks of microphone hardware quality.
The first is directivity, which determines the range of microphone reception: omnidirectional 360-degree uniform reception, suitable for venue and environment recording; Heart-shaped pointing focuses on the sound source in front of it, shielding the noise of the surrounding environment and adapting to live broadcast, dubbing and business recording; The eight characters point to the sound sources on both sides of the collection, which is mostly used for double interviews. The second is the frequency response range, which determines the timbre restoration ability. The standard frequency band for human voice adaptation is 85Hz—15kHz. The more complete the frequency band coverage, the more natural the timbre. The third is the signal-to-noise ratio, which directly controls the equipment noise floor. The higher the parameter value, the less the equipment's own current noise and the higher the radio purity.
Fourth, cross-border industry extension application
In the public's inherent impression, microphones only serve the audio-visual and media industries. In fact, industrial, medical and transportation fields have wider application scenarios and higher requirements. Industrial operation and maintenance is equipped with a high-precision radio microphone to collect the sound waves of equipment operation and accurately locate the abnormal sound of mechanical failure; Rail transit is equipped with a special noise-reducing microphone to filter the wind noise and wheel-rail noise, so as to ensure the smooth communication between trains. The artificial intelligence terminal relies on the micro microphone to realize voice wake-up and human-computer interaction; Medical equipment is equipped with radio components to collect respiratory and vocal sound waves to assist clinical health screening.
V. Current technical shortcomings and development trends
According to the landing scene of the industry, there are still two technical pain points in the current civil and commercial microphones: one is the balance problem of intelligent noise reduction, and the powerful noise reduction is easy to lose the texture of human voice, while the original sound is preserved, so the environmental noise is difficult to filter; Second, the stability of wireless transmission is insufficient, and there are widespread problems such as delay, audio compression and signal interference in wireless radio reception. Looking at the development trend of the industry, the research and development of microphone is iterating in three major directions: chip miniaturization, algorithm adaptive noise reduction and low-delay wireless transmission, taking into account hardware volume, radio accuracy and environmental adaptability.
A small microphone, seemingly simple in structure, actually combines acoustic physics, semiconductor hardware and digital algorithm. The effect of radio reception never depends on the appearance of work, but on the principle of transducer, hardware parameters and supporting links. Clarifying the underlying logic of microphone can not only avoid the misunderstanding of purchase, but also understand the basic technical context of audio industry and understand the ubiquitous but easily overlooked value of acoustic hardware.