A microphone is an essential device that plays a key role in converting sound waves into electrical signals. These signals can be transmitted over long distances, allowing sound to travel from one place to another. Upon reaching its destination, the electrical signal is reconverted into sound waves, making the microphone an integral part of communication systems worldwide. In this article, we will explore the different types of microphones, their functionality, and the history behind their development.
How Microphones Work: Sound to Electrical Signals
Microphones are widely used in various industries, including radio and television broadcasting, public speaking systems, and cinema halls. They serve the same purpose of transforming sound messages into electrical signals for transmission. But have you ever wondered how microphones actually convert sound into electrical waves?
When you speak into a microphone, the device captures the sound waves and transforms them into electrical currents. These electrical signals can then be transmitted over long distances. The component of a microphone responsible for this conversion is typically called a diaphragm, a part of the device that vibrates when hit by sound waves, generating an electric current based on the sound pattern.
Microphones in Everyday Devices
Interestingly, the part of a telephone you speak into is essentially a type of basic microphone. There are two main categories of microphones, based on how they convert sound into electrical signals:
- Pressure Type Microphones
- Velocity Type Microphones
Let’s delve deeper into each of these categories and their subtypes.
Pressure Type Microphones: How They Work
Pressure type microphones consist of a thin metal sheet, called the diaphragm, which is stretched tightly like the skin of a drum. This diaphragm is an integral part of the microphone’s electrical circuit. When sound waves strike the diaphragm, it vibrates, producing an electric current that corresponds to the sound.
There are several types of pressure microphones, each with its unique mechanism for converting sound into electrical signals:
Condenser Microphone
A condenser microphone operates by varying the capacitance of a condenser. The diaphragm in this microphone moves in response to sound waves, changing the distance between the plates of the condenser. This movement modifies the capacitance, which in turn generates an electrical signal based on the sound waves.
Moving Coil Microphone
In a moving coil microphone, a coil of wire is attached to the diaphragm. As the diaphragm vibrates, the coil moves within a magnetic field. This movement cuts through magnetic force lines, creating an electromagnetic potential difference. This electric potential represents the sound waves, converting the sound message into an electrical signal.
Crystal Microphone
A crystal microphone operates on the piezoelectric effect. When pressure is applied to a quartz crystal, an electric potential difference is generated. This type of microphone uses a piezoelectric crystal, with one end firmly attached and the other connected to the diaphragm. The vibration of the diaphragm causes pressure changes in the crystal, generating an electric current that corresponds to the sound waves.
Carbon Microphone
The carbon microphone works similarly to the transmitter in a telephone. In this microphone, carbon granules create a potential difference in the electric current. The sound waves cause variations in the carbon granules, producing an electrical signal that carries the sound message. A ribbon microphone, a variation of the carbon microphone, uses a thin metal ribbon instead of a coil.
Velocity Type Microphones: Functionality and Design
In velocity microphones, a thin strip of aluminum is placed in the center of a magnetic field. As sound waves hit the aluminum strip, it vibrates, causing changes in the magnetic field. This change creates an electromagnetic potential difference, which generates an electric current. This current carries the sound message through wires, converting sound into an electrical signal.
The Invention and Evolution of the Microphone
The development of the microphone is credited to multiple scientists. While Thomas Alva Edison made significant contributions, the first practical microphone was created by David Edward Hughes in 1878. Other notable inventors who contributed to the evolution of the microphone include Emile Berliner, Philip Rose, Francis Blake, and Henry Hennigs.
These scientists paved the way for the microphones we use today in various communication systems, from radio broadcasts to live concerts. Their work has revolutionized the way sound is transmitted over long distances, making global communication more efficient and accessible.
The Power of the Microphone
The microphone is an extraordinary device that has transformed how we communicate, perform, and broadcast messages. From its early days to its modern applications, the microphone continues to play a vital role in technology, media, and entertainment. Understanding the different types and mechanisms of microphones allows us to appreciate the complexity and functionality behind this everyday tool. Whether it’s a simple phone call or a live concert, the microphone remains a critical component in bringing sound to life.
