The structure of the mechanical-electrical transducer depends on the type of microphone. For example, it may be an electret microphone, a condenser microphone, a carbon microphone or a ribbon microphone. Microphone capsules are equipped with air-permeable protective foils or a cover with holes on the diaphragm side and on the back, so that the sound pressure can reach the diaphragm unhindered and escape from the back.
In addition to the transducer type determines the microphone capsule can have different directional characteristics. In addition, microphones with microphone capsules can be equipped with active amplifier components, they have different sensitivities, signal-to- noise ratios and output impedances.