Woofer

A woofer or bass speaker is a technical term for a loudspeaker driver designed to produce low frequency and mid-frequency sounds, typically from 50 up to 2000 Hz. The name is from the onomatopoeic English word for a dog's deep bark, "woof" (in contrast to a tweeter, the name used for loudspeakers designed to reproduce high-frequency sounds, deriving from the shrill calls of birds, "tweets"). The most common design for a woofer is the electrodynamic driver, which typically uses a stiff paper cone, driven by a voice coil surrounded by a magnetic field.

The voice coil is attached by adhesives to the back of the loudspeaker cone. The voice coil and the magnet form a linear electric motor. When current flows through the voice coil, the coil moves in relation to the frame according to Fleming's left hand rule for motors, causing the coil to push or pull on the driver cone in a piston-like way. The resulting motion of the cone creates sound waves, as it moves in and out.