Experiment: Straw Pipes
Sound always comes from a vibration. The speed of that vibration determines the pitch, or how high or low the sound is. Experiment with pitches by making different straw pipes. You can even play a song much like the cicadas we hear in the summer!
Materials
Thick straws (Tip: Save some of these to use in the next activity!)
Scissors
Tape
Ruler
Pen or marker
Instructions
- Seal one end of a straw by folding it over about one inch from the bottom and taping the end of the straw back on to itself. Tape the fold tightly so the fold stays in place. Check to see that the fold is airtight by blowing into the straw from the other end. Do this for three straws.
- Cut the straws to different lengths.
- Cut two pieces of straw that are 1-inch long. These are the spacers.
- Place a 5-inch piece of tape on the table with the sticky side up. Lay the straws down on the tape in order from shortest to longest with a spacer straw in between each one. The tops of the straw pipes should extend a little above the tape line. Once all straws are in place, secure them with tape. (Like this!)
- Place the straws so they vertical and the open end is resting on your bottom lip. Briskly blow over the open ends of each straw, experimenting with the angle to get the best sound.
- Make a scale by cutting the straws to specific lengths. Fold and tape the ends of eight new straws. Measuring from the fold, cut the straws to the following lengths: 19.5 cm, 17 cm, 15.5 cm, 14.5 cm, 13 cm, 11.5 cm, 10 cm and 9.5 cm. Number the straws from 1 to 8 with 1 being the longest straw and 8 being the shortest.
- Try playing a song following the "notes" below. Or, make up your own song!
Twinkle, Twinkle Little Star
11 55 66 5 44 33 22 155 44 33 2 55 44 33 211 55 66 5 44 33 22 1
Mary Had a Little Lamb
3212333 222 3553212333 322321
What's Happening?
As air is blown over the open end of the straw, it vibrates. The pitch, or frequency, is determined by the length of the tube, which acts as a resonating chamber. The longer the length, the lower the pitch or note. A long straw produces a low note, while a short straw produces a high note.
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