explain working of megaphone
megaphone works a bit like a funnel. It channels the sound you make and focuses it toward your target. In this way, it allows less sound to scatter in other directions.
In addition to directing sound toward your target, a megaphone also helps to increase your overall volume output. This effect is a result of the unique way in which sound waves work.
When sound waves move suddenly from narrow areas to wide open areas, some of the sound waves get reflected back toward the source. This happens when you speak. The sound waves leave the narrow space of your mouth and immediately encounter the vastness of open space, which causes some of them to be reflected back toward your mouth. This effectively reduces the volume of your speech.
When you speak into a megaphone, however, the sound waves leaving your mouth don't immediately encounter vast open space. Instead, they travel down the length of the cone, which gradually gets wider until the sound waves emerge from the end. When sound waves travel through a megaphone in this way, fewer waves bounce backward, thereby increasing the volume of your voice.
To amplify a voice effectively, a megaphone should be at least as long as the wavelength of the sound it's amplifying. Because human voices have wavelengths up to several feet long, the best megaphones (like the ones the cheerleaders use!) are usually manufactured as cones that are several feet long.