Why is the microphone a sound source?

Microphone, also called microphone and microphone, is responsible for converting sound changes into current changes. Carbon particle microphone is widely used in telephone communication system. Although information technology is very complicated, we can simplify it by grasping the following points. Information dissemination generally needs three links: source, channel and destination. A source refers to an information source or an entity that generates information to be transmitted, such as a speaker in a telephone system, and also includes a microphone used in a telecommunication system, and its output electric signal is used as a carrier containing information; Channel refers to the channel that transmits information. For example, coaxial cable systems include repeaters in telephone communication, earth station transceivers in satellite communication, antennas and repeaters on satellites. Receiver refers to the destination or receiver of information. In the telephone system, this is the listener and the earphone. The earphone converts the received electrical signal into sound for the listener to extract the required information. In addition, an encoder and a decoder are needed. Encoder refers to all devices that convert signals in information theory, and is the transmitting part of the terminal, including all devices from the source to the channel, such as quantizer, compression encoder, modulator, etc. Converting the signal output by the information source into a signal suitable for channel transmission; Decoder refers to the inverse transformation equipment of encoder, which converts the signal sent by the channel into the signal that can be received by the receiving end, including demodulator, decoder, digital-to-analog converter and so on.