What is Sound?
A popsicle (craft stick) harmonica is a groovy way to demonstrate the science of sound because all sounds are produced by a certain kind of motion. As you stretch a rubber band and then pluck it, the rubber band moves back and forth so rapidly that its motion appears blurred. The sound you hear comes from its motion. This very fast, back-and-forth motion is called a vibration. Vibrations are the source of all sounds.
Picture a stone thrown into a still body of water. The rings of waves expand indefinitely. The same is true with sound and what happens with a popsicle harmonica. Irregular repeating sound waves create noise, while regular repeating waves produce musical notes.
The human ear detects a sound wave. Also, sound waves have special characteristics that make them unique.
Science of Sound: The vibrating air enters your ears and hits against your eardrums causing them to vibrate.
Your ears vibrate in a similar way to the original source of the vibration, this then sends a message to your brain and the brain hears the sound, allowing you to hear many different sounds.
Not all vibrations create sounds that humans can hear. Human ears sense vibrations within speeds between 20 – 20,000 vibrations per second. If a vibration is too fast or too slow, it will not be heard as “sound” by humans. One vibration too fast for human hearing is the ultrasonic signal emitted by bats for echo-locating. Vibrations that are too slow for human hearing include ocean waves and earthquakes. We detect these vibrations by seeing and feeling them, but we do not hear them.
Did You Know? Dogs can hear sound at a higher frequency than humans, allowing them to hear noises that we can’t.
How does sound move?
The matter that transports the sound is called the medium. Sound waves can travel through all sorts of mediums. You can hear sound waves that have traveled through air, but sound can also travel through a solid or a liquid. Water, wood, and the Earth are some examples of mediums.
If there is no medium to carry the sound to your ears, you cannot hear the sound. In deep space there is no sound. The large empty areas between stars and planets do not have any molecules to vibrate to produce sound. There is no sound there.
Have you ever tried hearing something in the bathtub when you put your head under water or in a pool? The sound may sound muffled but you probably hear a lot of sound that you wouldn’t when sitting up in the bathtub. In fact, sound moves around four times faster when it travels through water than when it travels through air.
Materials to make a Popsicle Harmonica:
• 2 Popsicle sticks
• 1 Wide rubber band
• 2 Small rubber bands
• 2 Pieces of paper: 2 cm wide and 6 cm long
• Scotch Tape
Procedure for a Popsicle Harmonica:
1. Lay one stick on top of the other with the paper strips underneath and spaced at either end.
2. Fold over both pieces of paper on either side of the sticks.
3. Secure paper with tape ensuring the tape does not touch the sticks.
4. Carefully remove the craft stick from underneath. Then stretch the longer rubber band around the length of the top stick. Place the bottom stick directly under. then secure them both with the two smaller rubber bands.
5. Voila! A groovy popsicle harmonica made especially by YOU! Next, press your lips, then gently blow to make some groovy harmonica sounds and music!
While blowing on the harmonica the air causes the rubber band to vibrate and make a groovy sound.
Popsicle Harmonica Safety for STEMists
Adult supervision and assistance is required for all the activities on our website.
Craft sticks can have small splinters. Be sure to inspect each stick to make sure they are safe to go into a child’s mouth.
If you decorate the harmonica with markers, the ink or other materials may come off on or in a child’s mouth.
the branch of physics that deals with sound and sound waves.
vibrations that travel and can be heard when they reach a person’s or animal’s ear.
Science of Sound Facts
• The speed of sound is around 1,230 kilometers per hour (km/hr)
• When cracking a whip, the loud noise you create occurs because the tip is moving so fast it breaks the speed of sound!
• Bats can see in the dark by using echolocation. They bounce their sound waves off objects to find their way. Dolphins also use echolocation underwater.
• Although music can be hard to define, it is often described as a pleasing or meaningful arrangement of sounds.
If your STEMists are fascinated by the science of sound, check out our “Good Vibrations” single box today!
Also On The Blog: 4 Groovy Activities to Teach about Vibration and Sound Energy
For more challenging play try a monthly-themed Groovy Lab in a Box. There is no better way to educate your STEMists than to keep their minds screen-free, working to create, design and solve, through the engineering design process and STEM-related activities. Furthermore, our monthly box activates thinking, questioning, inquiring and original creation as we guide children through scientific inquiry and engineering design process.