Working Principle of a Condenser Microphone - The varying sound pressure changes the spacing between a thin metallic membrane and a stationary plate, producing electrical signals which “copy” the sound pressure. Salient Features: Works with a wide range of sound frequencies. Although expensive, it is considered as the best microphone for recording applications. Working Principle of a Dynamic Microphone - The varying sound pressure moves the cone diaphragm and the coil attached to it within a magnetic field, producing an electromotive force that generates electrical signals which “copy” the sound pressure. Salient Features: The inverse of a dynamic loudspeaker and relatively cheap and rugged. Working Principle of a Headphone or an Earbud - Wires carry the audio signal from the stereo into the coil and back again. The coil around the plastic cone becomes an electromagnet when current passes through it. And because the coil is within a magnetic field, a force is generated on the coil. In response to the audio signal, the coil moves together with the flexible flat crinkly cone moving the air within the headphone/earbud enclosure and in the ear canal producing sound. Salient Features: Headphones and earphones are small loudspeakers clamped over the ear/s. Basically, each speaker consists of stereo wires, plastic cone diaphragms, coils attached to the cone, and magnets built inside cased or padded sound chambers Working Principle of a Studio Monitor or a Speaker - The electric current imaging the audio signal is sent through the coil that is within the magnetic field. A force is generated that moves the magnet and the cone attached to it producing the sound corresponding to the analog or digital signal. Salient Features: The studio monitor is a dynamic reference speaker designed to produce an accurate image of the sound source. Most hobby studio use the active type studio monitor. It has a built-in amplifier and functions when plugged ointo an outlet and a sound source. A dynamic speaker, like the studio monitor, has the same essential parts as a dynamic microphone. But unlike the microphone or headphone where the voice coil is attached to the cone diaphragm, on the studio monitor, it is the permanent magnet that is attached to the cone while the coil is wound around a fixed core.