How Does a Harmonica Work?
Materials in the box
1. Two jumbo craft sticks
2. One 3 X 5 inch index card
3. Three rubber bands
Materials from your house
1. Scissors
How do I begin?
1. Create two “sliders.” Wrap 1 cardstock strip around each end of the jumbo craft sticks and secure the ends of the cardstock strip with Scotch tape (provided with the "How Does a Glider Fly" experiment).
2. Ensure that the sliders can move freely.
3. Take the wider rubberband and wrap it lengthwise around the craft stick and sliders. Make sure it lays flat.
4. Now stack the craft stick with the rubber band on top of the plain craft stick.
5. Wrap the skinnier rubber bands around each end of the craft sticks.
6. Blow on the side of the harmonica into the gap between the craft sticks and the two sliders. Move the sliders together or apart. Blow hard, and then blow softly. Does the sound change?
What just happened?
Vibrations need a medium like air to travel and produce sound that finally reaches our ears. Higher pitched sounds are created by waves with a higher frequency. The pitch, or frequency, produced is equal to the number of times per second (hertz) that the rubber band vibrates. You can change the pitch of your harmonica by moving the slider(s) or blowing air at different speeds. When the sliders are closer together, the pitch will be higher.
Airflow around the rubber band also affects the sound. The air flowing above and below causes the rubber band between the craft sticks to vibrate due to disturbance in the air. Like most objects, the rubber band has a natural frequency at which it vibrates most easily.
Exploring Further
1. Does the length of the rubber band make a difference in the sound frequency?
2. Does the material (rubber band, string, metal wire) make a difference in vibrations?
1. Two jumbo craft sticks
2. One 3 X 5 inch index card
3. Three rubber bands
Materials from your house
1. Scissors
How do I begin?
1. Create two “sliders.” Wrap 1 cardstock strip around each end of the jumbo craft sticks and secure the ends of the cardstock strip with Scotch tape (provided with the "How Does a Glider Fly" experiment).
2. Ensure that the sliders can move freely.
3. Take the wider rubberband and wrap it lengthwise around the craft stick and sliders. Make sure it lays flat.
4. Now stack the craft stick with the rubber band on top of the plain craft stick.
5. Wrap the skinnier rubber bands around each end of the craft sticks.
6. Blow on the side of the harmonica into the gap between the craft sticks and the two sliders. Move the sliders together or apart. Blow hard, and then blow softly. Does the sound change?
What just happened?
Vibrations need a medium like air to travel and produce sound that finally reaches our ears. Higher pitched sounds are created by waves with a higher frequency. The pitch, or frequency, produced is equal to the number of times per second (hertz) that the rubber band vibrates. You can change the pitch of your harmonica by moving the slider(s) or blowing air at different speeds. When the sliders are closer together, the pitch will be higher.
Airflow around the rubber band also affects the sound. The air flowing above and below causes the rubber band between the craft sticks to vibrate due to disturbance in the air. Like most objects, the rubber band has a natural frequency at which it vibrates most easily.
Exploring Further
1. Does the length of the rubber band make a difference in the sound frequency?
2. Does the material (rubber band, string, metal wire) make a difference in vibrations?