Inside a dynamic microphone are voice coils attached to a diaphragm and surrounding a magnet. When sound waves hit the diaphragm, the diaphragm moves back and forth, causing the voice coils to vibrate as well. The vibration of the coil creates an electrical signal. Unlike a condenser microphone, a dynamic microphone can operate without a power supply. A durable, commonly-used microphone, it is considered especially good for loud sounds.