A speaker produces sound by using magnetic forces to push or pull a thin surface—the speaker cone—toward or away from the listener. As the cone moves forward, it compresses the air in front of it and as the cone moves backward, it rarefies the air in front of it. These compressions and rarefactions are what produce sound. But if you try to drive the cone into motions that are too extreme by turning up the volume of an amplifier too high, the cone will reach the limits of its motion. At that point, the cone may tear away from the electromagnetic coil that pushes it back and forth or it may tear away from the supports at its outer edge. The electromagnetic coil may also burn up because of overheating. All of these failures are lumped together as "blowing a speaker."
