A megaphone, speaking-trumpet, bullhorn or loud hailer is a portable, usually hand-held, funnel-shaped device whose application is to amplify a person?s voice towards a targeted direction. This is accomplished by channeling the sound through a funnel, which also serves to match the impedance of the voice cords to the air. The natural human voice tends to spread evenly in all directions, whereas when it is sent through a megaphone, the sound is concentrated in a given direction and the coupling of its energy to the air optimised.[1] The trade-off is that if a listener is to the side, it is more difficult to hear what is being said. An electronic megaphone amplifies sound to a higher decibel level. It consists of a microphone, an amplifier and a loudspeaker.
Common uses for megaphones are at sporting events, political functions and generally when one needs to address congregations of people in open spaces.
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