Fast and Easy Science Fair Projects: Now Soft/ Now LOUD

     This is my 32nd hub on Fast and Fair Science Fair Projects. This one is extremely easy, useful and fun! I'm sure you'll enjoy reading and trying out this one too, especially kids! Have fun!

Amplifying sound through reflection

Purpose: To understand and demonstrate how sound vibrations can be amplified through the use of a "sounding board."

Overview: A sound something makes can often be made louder by focusing it, reflecting it, or making a second object vibrate or resonate.

      Did you ever see a cheerleader using a megaphone? A megaphone is a small opening at one end and a large opening at the other. Sound is focused by a megaphone. Speaking into the end with the small opening makes the user's voice louder. It can also be used in reverse, holding the small opening end up to your ear to collect distant or faint sounds and make them louder (see Project 22).

      Another way to amplify sound (make it louder) is to cause the vibrations to be expanded to another object. The hollow wooden body of an acoustic guitar gives the vibrating strings of the instrument more volume and better tone quality.

     A third way is to use something called a "sounding board." The sounding board in a piano reflects the sounds of the vibrating piano strings, making the sound louder.

Hypothesis: Hypothesize that sounds from a vibrating body can be amplified by adding a sounding board.

Procedure: Take a bobby pin, the flat metal hairpin used to hold ones hair in place, and bend one of the prongs until it makes a 90-degree angle (so that the bobby pin forms an "L" shape). Normally, one prong of a bobby pin is straight and the other contains zigzag curves. With your thumb and index finger, tightly hold the bobby pin near the bottom of the straight prong, holding only about 1/2 inch (1 cm) of the prong. Use the thumb of your other hand to sharply flick the end of the curved prong, making a downward stroke. Listen closely to hear the faint sound.

      We are going to keep the vibrating bobby pin Constant; the Variable will be the addition of a block of wood to act as the sounding board.

      Now, ask an adult to help you mount the bobby pin on a small block of wood. The wood should be about 1 inch (2.5 cm) thick by 5 to 6 inches (13-15 cm) square or rectangular. (The exact length and width are not important.) Mount the bobby pin by placing two staples from a staple gun or two small nails (brads) to attach the bobby pin to the wood block. The nails can be tapped partway into the wood then bent over the pin, using the hammer. About 1/2 inch (1 cm) of the straight prong should be mounted flush against the wood block, and the rest of the bobby pin should rise above the block. If staples are used, give them a tap with the hammer to ensure that the bobby pin is firmly touching the wood. Sharply flick the end of the curved prong with your thumb, with a downward stroke. Is the tone you heard before louder now?

Results and Conclusion: Write down the results of your experiment. Come to a conclusion as to whether or not your hypothesis was correct.

Something more: 1. Will increasing the size of the wood block amplify the sound even more? At what size does further increase make no difference in the sound?

      2. Can you make the sound even louder by resting the board on a large wooden table, holding it tightly against a wall, or against a large metal pan?

     Thanks for reading this one! Hope you liked it! If you want more on Fast and Easy Science Fair Projects, you can try my other Hubs relating to the topic. Here are five of my Latest Hubs on Fast and Easy Science Fair Projects for you: