Make a Harp

Sound

Things You Will Need
• Cardboard or plastic shoebox
• 10 to 20 rubber bands of varying thickness

   

   

   

Do This

1. Stretch the rubber bands around the box in one direction.
2. Space the rubber bands so that they are not touching each other.
3. Pull the bands with your fingers to play your "harp."
4. Pluck the individual bands to hear the different notes.
5. Push your finger on the end of a band to stretch it tighter, then pluck the band with your other hand.
6. Observe the different notes the rubber bands make.

What Should Have Happened

Musical instruments, such as a harp, make sounds when the strings set up vibrations in the air. If the vibration of the air reaches your ears, it makes the eardrum inside each ear vibrate so you can hear the sounds. Sounds travel through the air like waves or ripples across a pond. High sounds make waves that are close together. Low sounds make waves that are further apart. The tighter the rubber band, the higher the note it made. The looser the rubber band, the lower the note it made. Just like ripples on a pond, sound waves become weaker further away from a sound. This is why you can hear better when you are close to the source of the sound.