Electromagnetic buzzers provide low frequencies in a compact size and with higher temperature ratings when compared to piezoelectric buzzers. The electromagnetic buzzer is comprised of a metal diaphragm, coil, magnet, pole, and yoke. When a voltage is applied to the buzzer via the pins (8), a magnetic field is generated via a coil (9), causing the magnet (3) to move, and the metal diaphragm (2) to vibrate. At the metal diaphragms' resonant frequency, air pressure waves are created that the human ear interprets as sound. Electromagnetic type buzzers are dependent on the polarity of the voltage source, so care should be taken to ensure the buzzer is correctly installed into the circuit. Typically these buzzers will have either a + sign on the case or pins will be different lengths to indicate voltage input polarity. Notice on the graph to the right that the frequency response is less defined as those distinct peaks of amplitude of the piezoelectric buzzers. This allows for these buzzers to produce a more dynamic range of frequencies with strong sound pressure.