A megaphone works by forcing the sound that comes from a person's voice into one direction, making it louder. Megaphones come in an electric version called a bullhorn, and a non-electric version, which is the one with which many people are familiar.
The bullhorn has four major components. It has a microphone, speaker, power supply and amplifier. When a person speaks into the microphone located at the mouthpiece of the bullhorn, the amplifier makes the voice louder because it is projected through the speaker. How much the sound is amplified depends on the power of the speaker. Unlike a manual megaphone, the person speaking does not need to yell when using a bullhorn.
A manual megaphone directs the voice into one spot. Its cone shape creates a gradual transition for sound to travel. As sound leaves the small area of the mouth, it spreads out in every direction, restricting its range. Megaphones allow a person to aim the sound in the direction they want it to go. The longer the megaphone, the farther it will project the voice. This is why people who need to project their voices long distances, like cheerleaders, use a long megaphone. Professional megaphones give a greater distance than non-professional models.