A megaphone, speaking-trumpet, bullhorn or loud hailer is a portable, usually hand-held, funnel-shaped device whose application is to send a person’s natural voice toward a targeted direction for a specified purpose. 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 optimized. 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. Inventor Thomas Edison exhibited an early version of the megaphone at the Paris Exposition.] ------------- Common uses for megaphones are at sporting events, political functions and generally when one needs to address congregations of people in open spaces. Police officers often use them to communicate with suspects and rescue crews during operations to communicate with the victim. ----------------------- Another lesser known use is as vocal distortion by musicians. For example, Tom Waits is know for using a megaphone in a variety of songs. The megaphone gives off a kind of gritty, untamed effect valued by many musicians.