What Is a Microphone?

 What Is a Microphone?

A microphone is a device that converts sound into an electrical signal.

It is also commonly referred to as a microphone for short. By converting sound vibrations into electrical signals, microphones are mainly used for communication, recording, and voice amplification.

Whether digital or analog, microphones are generally referred to as audio input devices. While a microphone is an audio input device, a device that converts electrical signals into audio and outputs them is called a speaker.

什么是麦克风？

麦克风是一种将声音转换为电信号的设备。

它通常也简称为麦克风。通过将声音振动转换为电信号，麦克风主要用于通信、录音和扩音。

无论是数字还是模拟，麦克风通常被称为音频输入设备。虽然麦克风是音频输入设备，但将电信号转换为音频并输出的设备称为扬声器。

Uses of Microphones

Microphones are used as audio input devices and are used in various forms for different purposes, such as broadcasting, music recording, and noise level meter measurements. They are also built into many electronic devices such as smartphones, PCs, IC recorders, and cameras for voice input and voice recognition.

They are also useful as loudspeakers for delivering voices to a large audience at concerts, live performances, lectures, and events. They are widely used in familiar places such as karaoke, sports events, and school events.

麦克风的用途

麦克风用作音频输入设备，以各种形式用于不同的目的，例如广播、音乐录制和噪音计测量。它们还内置于许多电子设备中，例如智能手机、个人电脑、IC 录音机和相机，用于语音输入和语音识别。

它们还可用作扬声器，在音乐会、现场表演、讲座和活动中向大量观众传递声音。它们广泛用于卡拉 OK、体育赛事和学校活动等熟悉的地方。

Principle of Microphones

Microphones convert acoustic vibrations into electrical signals, and there are various methods of this conversion. Specifically, there are dynamic types, condenser types, etc.

1. Dynamic Type

The dynamic type has a simple structure, with a coil attached to a diaphragm that converts sound into an electrical signal. The diaphragm called a diaphragm, voice coil, and magnet are used, and the magnetic flux is changed by the sound vibration and converted into an electrical signal.

The dynamic type is robust, easy to handle, and produces powerful sound, so it is often used for performances, live music, lectures, etc.

2. Capacitor Type

The capacitor type has a complex structure. The diaphragm serves as the electrode for the capacitor, which converts sound into an electrical signal. The diaphragm, which is charged with electricity, and the back plate, which is called the back plate, are combined to form an electrical capacitor. The distance between the diaphragm and the back plate changes the electric field in the capacitor due to changes in vibration. This change is used as the electrical input. It is characterized by higher sensitivity than the dynamic type.

Condenser microphones are more complex in construction, require internal electronic circuits, and are more expensive than dynamic microphones.

麦克风的原理

麦克风将声振动转换成电信号，这种转换有多种方法。具体来说，有动圈式、电容式等。

1. 动圈式

动圈式结构简单，在振膜上安装线圈，将声音转换成电信号。使用称为振膜的振膜、音圈和磁铁，通过声音振动改变磁通量并转换成电信号。

动圈式坚固、易于操作且声音强劲，因此经常用于演出、现场音乐、演讲等。

2. 电容式

电容式结构复杂。振膜作为电容器的电极，将声音转换成电信号。带电的振膜和称为背板的背板组合在一起形成电电容器。振膜和背板之间的距离因振动变化而改变电容器中的电场。该变化用作电输入。其特点是灵敏度比动圈式高。

电容式麦克风的结构更复杂，需要内部电子电路，并且比动圈式麦克风更昂贵。

Types of Microphones 

1. Moving Coil Type

Moving coil-type microphones convert sound = air vibrations into electrical signals when a coil attached to a diaphragm, which is a diaphragm, moves in a magnetic field. This structure is similar to the magnetic pickup microphones used for guitars and basses, where the vibration of the strings generates an electrical signal.

2. Ribbon Type

A ribbon-type microphone uses a thin metal foil ribbon hanging between slits sandwiched by magnetic poles as a vibrating system, and the sound vibration generates an electrical signal at both ends of the ribbon. The lightweight structure of the vibrating system allows the microphone to pick up sound in a wide range of frequencies from high to low, and the frequency response is less peculiar and more natural sounding.

3. Carbon Microphone

Carbon microphones are microphones that utilize the change in contact resistance of carbon powder to obtain audio signals. It is constructed by placing carbon powder between two plate-shaped electrodes.

When a direct current is applied between the electrodes with one fixed electrode and the other movable electrode, the movable electrode vibrates due to voice, and the contact resistance between the electrode and the carbon powder changes to obtain a voice signal. Carbon microphones are robust and have very high sensitivity, but since they use the change in contact resistance of the carbon powder, they have the weakness of easily distorting the sound.

4. Piezoelectric Microphone

Piezoelectric microphones use piezoelectric elements to obtain sound signals by vibrating electrodes caused by voice. The sensitivity is high, but the output power is low.

They are mainly used in situations where bandwidth is limited. Wireless communication and concrete microphones are typical examples.

5. Laser Microphone

A laser microphone is a type of microphone that uses a laser beam to detect and demodulate light fluctuations caused by voice vibration using a light-receiving element. It is intended for use in environments and situations where conventional microphones are difficult to use, and several forms exist, including those based on the Doppler effect and interferometry.

Microphones called ion microphones or plasma microphones, which generate plasma without a diaphragm and apply sound waves to it to extract modulated sound waves, are also being studied.

麦克风的种类

1. 动圈式

动圈式麦克风通过安装在振动膜上的线圈在磁场中移动，将声音=空气振动转换为电信号。这种结构类似于吉他和贝司使用的磁拾音麦克风，琴弦的振动会产生电信号。

2. 带式

带式麦克风使用悬挂在夹有磁极的狭缝之间的薄金属箔带作为振动系统，声音振动在带的两端产生电信号。振动系统的轻量结构使麦克风能够拾取从高到低的广泛频率范围内的声音，频率响应更少奇特，听起来更自然。

3. 碳麦克风

碳麦克风是利用碳粉接触电阻的变化来获取音频信号的麦克风。它是通过在两个板状电极之间放置碳粉而构成的。

当在一个固定电极和另一个可动电极的电极之间施加直流电流时，可动电极会因声音而振动，电极与碳粉之间的接触电阻会发生变化，从而获得声音信号。碳麦克风坚固耐用，灵敏度非常高，但由于利用了碳粉的接触电阻变化，因此存在声音容易失真的弱点。

4.压电麦克风

压电麦克风使用压电元件，通过声音使电极振动来获得声音信号。灵敏度高，但输出功率低。

它们主要用于带宽有限的场合。无线通信和混凝土麦克风就是典型的例子。

5.激光麦克风

激光麦克风是一种使用激光束通过光接收元件检测和解调由声音振动引起的光波动的麦克风。它旨在用于传统麦克风难以使用的环境和场合，存在几种形式，包括基于多普勒效应和干涉测量的形式。

另外，还有被称为离子麦克风或等离子麦克风的麦克风正在研究中，它们无需振膜就能产生等离子体，并对其施加声波，从而提取调制后的声波。