Loudspeakers convert electrical audio signals into sound by moving a diaphragm. The dynamic (moving-coil) driver is the dominant design, supplemented by electrostatic, planar magnetic, and piezo elements in specific roles. Modern developments include advanced materials, neodymium magnets, horn and waveguide optimization, DSP, active (powered) speakers, and networked PA and smart speaker systems. Proper placement and system tuning remain essential for even coverage and low distortion.
How loudspeakers convert electricity into sound
A loudspeaker converts an electrical audio signal into audible sound by moving air. The most common type today is the moving-coil (dynamic) driver. A small coil of wire (the voice coil) sits in the gap of a magnet and attaches to a lightweight cone. When audio current flows through the coil, electromagnetic forces move the coil and cone back and forth, creating pressure waves we hear as sound.Manufacturers now use more precise materials than early designs. Cones and diaphragms are made from treated paper, polypropylene, aluminum, woven aramid (Kevlar), or carbon-fiber composites. Magnets are often rare-earth neodymium for smaller, lighter drivers with strong magnetic fields. Modern voice coils, surrounds, and motor designs improve efficiency, extend bandwidth, and reduce distortion.
Other driver types
Electrostatic speakers use a charged, thin diaphragm between fixed plates; the varying voltage moves the diaphragm. They can deliver very low distortion and a detailed midrange but require high-voltage bias and large panels, so they remain a niche for high-end audio.Planar magnetic drivers and ribbon designs use a thin membrane with conductors that interact with magnets to produce motion. Piezoelectric and small crystal elements still appear in low-cost tweeters, buzzers, and some specialized applications, but they are uncommon in high-fidelity loudspeakers today.
Horns, compression drivers, and directivity
Horn-loaded drivers and compression drivers remain standard in professional sound reinforcement. Horns increase efficiency and control directivity so sound projects farther with less power. Advances in waveguide and horn geometry, plus digital signal processing (DSP), give modern systems precise coverage and reduced feedback.Power, sensitivity, and modern systems
Speaker sensitivity is commonly in the 85-95 dB SPL (1 W/1 m) range for consumer drivers; professional systems can surpass that. Power-handling ranges from a few watts for small active speakers to hundreds or thousands of watts in concert and stadium systems. Many loudspeakers are now active (powered) with built-in amplifiers and DSP for crossover, limiting, and room correction.Line-array arrays, networked systems, and powered "smart" speakers (with Bluetooth, voice assistants, or network audio) have changed installations. Public address (PA) systems still rely on careful speaker placement, grouping, and tuning to achieve even coverage across venues from classrooms to stadiums.