Today’s Wonder of the Day was inspired by Sahar. Sahar Wonders, “how does our yelling increase when we put our hands around our mouth?” Thanks for WONDERing with us, Sahar!
Greetings Wonder Friend! We have an important that we need to get out. Will you help us? Great! Just stand to your feet and loudly proclaim to everyone within earshot: WONDEROPOLIS IS WONDERFUL! GO READ THE WONDER OF THE DAY!
Were you able to make your voice heard? If you're like many kids, you might have cupped your hands around your mouth before shouting the . If you did so, you created your own homemade version of a megaphone!
Wait a second…aren't megaphones those big cone-shaped things that cheerleaders hold when they're shouting out cheers during a game? Yes, they are! And there's also a smaller, electronic version called a "bullhorn" that you've probably seen police use in movies when they're trying to communicate with a large crowd.
How do these devices — or even your cupped hands — work to help you communicate with others? The secret of a megaphone is its cone shape, and that shape helps to amplify your voice for a couple of reasons.
First, the cone shape of a megaphone directs your voice toward your target. When you speak, sound emanates from your mouth in all directions at once. Only a part of your sound output goes in the direction of your intended target.
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.
If you're using a bullhorn, though, it doesn't need to be several feet long. If you've ever seen a bullhorn, you know that it is shaped like a cone, but it's much smaller. Yet, it can greatly amplify your voice thanks to the amplifier and speaker that electronically amplify your voice.