Explorers

The Explorers spent a session in November 2011 investigating sound waves and how they can be changed and manipulated to make music.

We started with a quick description of how sound waves are created through a disturbance that causes vibrations that are transmitted through the air. These waves travel from the source of the vibration, through the air, to the ear of a listener, where they in turn vibrate tiny bones. The ear then sends a signal to the brain, which interprets the whole process as sound.

Of course, not all sounds sound the same—they come in a wide variety of different pitches. These pitches are a result of the frequency of the vibrations—the more rapid the vibrations, the higher the frequency of the sound waves and the higher the pitch of the sound. Closely related to the frequency of the sound waves is something called wavelength. Since sound waves travel at a constant speed through a medium (such as air), as the frequency gets higher (meaning the number of waves passing by gets higher) this requires a corresponding smaller distance between the individual waves. This distance between the sound waves is the wavelength—and the higher the frequency, the smaller the wavelength.

Music takes advantage of these concepts to create different pitches using the same instrument. The Explorers saw demonstrations of two instruments that change the frequency (and thus the pitch) of their sound in somewhat different ways. First, Mr. Ramsey showed how blowing across the opening in an empty water bottle can create a sound—a fairly sad little sound with only one note, perhaps, but still a sound. Next, club assistant extraordinaire Lissa played some notes on her flute. She was blowing across the opening in the flute similarly to the water bottle, but by closing and opening the various holes on the flute she was able to change and control the notes of the instruments.

Next, Mr. Berry showed how a similar effect is created in an instrument that you actually blow into rather than across—in this case, an oboe. He showed that simply blowing into the instrument isn’t good enough—you have to have something that creates a vibration. In an oboe (and other related instruments) this “something” is called a reed—a thin piece of wood (or in the case of the oboe two pieces of wood) that vibrates when placed into the mouth and blown across in the right manner.

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Now came the time to make some instruments of our own. Of course, we couldn’t afford to buy flutes or oboes for everyone, but we could afford something almost as good: straws. By chomping one end of a straw flat and then trimming off the corners, the students were able to create “reeds” on the tips of the straws. With a little practice, they were then able to stick these ends of the straws in their mouths, blow, and lo and behold—we had sounds! Granted, they sounded more like rude party favors than flutes or oboes, and they each only made a single note, but still.

After a few joyful minutes of seeing how much noise 30 fifth-graders can make with new toys, it was time to try making different notes. We accomplished this in two ways. First, the students cut a slit in a second straw so that it could be slid into the end of the first one. By moving this second straw in and out of the first while blowing, the pitch was changed—essentially, we had created the world’s cheapest trombones. Next, we used hole punches to make finger holes in our straws. By covering and uncovering different holes, the students were again able to make different notes. Perhaps not quite as sophisticated as Mr. Berry’s oboe or Lissa’s flute, but then again, if either of those broke down they would be much harder and more expensive to replace than our straws!

Finally, the best part of the meeting came—the moment when the parents arrived to pick up the students and all of those new straw instruments went home to serenade unsuspecting families. Ah, the sweet music that was undoubtedly made all over town that night.

To read more about this activity, see the links below from previous years.

Straw Instruments 2

Straw Instruments 1