Microphones are devices that convert sound waves (acoustic energy) into electrical signals (electrical energy). They accomplish this conversion through various transducer technologies. The most common types of microphones are dynamic microphones, condenser microphones, and ribbon microphones, each with its unique transduction method. Here's how each type works:
Dynamic Microphones: A dynamic microphone uses a diaphragm, coil, and magnet to convert sound waves into electrical signals. The diaphragm is a thin, movable membrane that vibrates in response to sound waves. This diaphragm is attached to a coil of wire that sits within a magnetic field produced by a permanent magnet. When the diaphragm moves due to sound pressure variations, the coil moves with it, generating a varying electrical current through electromagnetic induction. This current represents the sound wave and is sent to the microphone's output connector.
Condenser Microphones: Condenser microphones, also known as capacitor microphones, utilize a charged capacitor to convert sound waves into electrical signals. These microphones consist of two plates: a fixed backplate and a movable diaphragm (usually made of a thin conductive material). The backplate is permanently charged with an electric charge, creating an electric field between the plates. When sound waves hit the diaphragm, it vibrates, causing the distance between the plates to change. This variation in distance results in a change in capacitance, which in turn creates an electrical signal proportional to the sound waves. To maintain the constant charge on the capacitor, condenser microphones require an external power source, either through batteries or phantom power supplied by an audio interface or mixer.
Ribbon Microphones: Ribbon microphones use a thin metal ribbon (usually made of aluminum) as their transducer element. This ribbon is suspended in a magnetic field, and when sound waves strike it, it vibrates in response. The movement of the ribbon within the magnetic field generates a small electrical current, which is the microphone's output signal. Ribbon microphones are delicate and require careful handling due to the fragility of the ribbon element.
Regardless of the microphone type, the resulting electrical signal from the transducer is then sent to an audio interface, mixer, or other recording equipment, where it can be amplified, processed, and recorded or transmitted as needed.
It's essential to choose the right microphone type for specific applications, as each type has its advantages and disadvantages in terms of sensitivity, frequency response, transient response, and durability.