Passive radiators are used in many modern speakers because they are a terrific way to get a whole lot of extra oomph out of a sound system without diverting valuable energy into creating that lovely bass effect that we all enjoy so much. They are common in smaller, modern, computer-driven speaker systems largely because they are designed to sound like a bigger speaker while remaining quite small. They are a relatively inexpensive way to deliver a full-throated, rich, and robust sound experience in a way that is mechanically efficient and ideal for the miniaturization that mobile sound systems require.