The Core Principle of Sound Production
A speaker produces sound by converting an electrical audio signal into mechanical vibrations. This process relies on electromagnetism, where changes in an electrical current create a fluctuating magnetic field, which in turn causes physical movement. Ultimately, this movement pushes and pulls on the surrounding air, generating the sound waves we hear.
Key Components and Their Roles
The main components of a dynamic speaker include a permanent magnet, a voice coil, and a diaphragm (often a cone). The voice coil is a cylinder of wire attached to the diaphragm and suspended within the magnetic field of the permanent magnet. The diaphragm is a flexible material designed to move air effectively, and the spider and surround hold the cone in place while allowing it to move freely.
From Electrical Signal to Vibration
When an electrical audio signal passes through the voice coil, it creates a temporary electromagnetic field. As the electrical current in the signal fluctuates, so does the voice coil's magnetic field. This fluctuating field interacts with the steady magnetic field of the permanent magnet, causing the voice coil, and therefore the attached diaphragm, to move rapidly back and forth in response to the changes in the electrical signal.
Creating Audible Sound Waves
The rapid in-and-out movement of the speaker's diaphragm acts like a piston, pushing and pulling on the air molecules in front of it. When the diaphragm moves forward, it compresses the air; when it moves backward, it creates a rarefaction (area of lower pressure). These alternating compressions and rarefactions propagate through the air as longitudinal sound waves, traveling to our ears and being interpreted as sound.