We've examined most of the major components in a car audio system. No matter how powerful the amplifier or how trick the head unit, none of that matters if you don't have speakers to reproduce the sound. Let's take a close look at car audio loudspeakers, how they interface with the other components, and what sets them apart from the rest of the system. First, let's talk about sound.
Sound waves travel through the atmosphere by vibration.
Here's an example. A friend speaks to you. Her vocal chords vibrate, causing the air around her larynx to begin moving, meaning the nearby molecules of air collide with one another. These molecules in turn collide with other molecules, which in turn collide with other molecules, and so on. The sound eventually reaches your eardrums, where the vibration is interpreted by your brain as sound.