A microphone (colloquially called a mic or mike) is an acoustic-to-electric transducer or sensor that converts sound into an electrical signal.
In 1876, Emile Berliner invented the first microphone used as a telephone voice transmitter.
Microphones are used in many applications such as telephones, tape recorders, karaoke systems, hearing aids, motion picture production, live and recorded audio engineering, FRS radios, megaphones, in radio and television broadcasting and in computers for recording voice, speech recognition, VoIP, and for non-acoustic purposes such as ultrasonic checking or knock sensors.
Most microphones today use electromagnetic induction (dynamic microphone), capacitance change (condenser microphone), piezoelectric generation, or light modulation to produce the signal from mechanical vibration.
A Loudspeaker (or speaker) is an electroacoustic transducer that converts an electrical signal into sound.
The speaker pulses in accordance with the variations of an electrical signal and causes sound waves to travel through either air or water.
The term "loudspeaker" may refer to individual transducers (known as "drivers") or to complete speaker systems consisting of an enclosure including one or more drivers. To adequately reproduce a wide range of frequencies, most loudspeaker systems employ more than one driver, particularly for higher sound pressure level or maximum accuracy. Individual drivers are used to reproduce different frequency ranges. The drivers are named subwoofers (for very low frequencies); woofers (low frequencies); mid-range speakers (middle frequencies); tweeters (high frequencies); and sometimes supertweeters, optimized for the highest audible frequencies.