VOCAL VOWELS

Hollow plastic models of the human vocal tract turn the squawk of a duck call into vowel sounds.

Note: All of the sounds below are in AIFF format. If you have a Macintosh these should play directly within Mosaic. If you have some other client, you'll have to find a helper application that will play AIFF sounds. Sorry, I couldn't stand the 8kHz sample rate of AU files!

To do and notice

• Here is the sound source. It's really a re-packaged duck call! Notice the reed above the curved wooden surface. Air blows past the reed (from right to left) causing it to vibrate and produce a buzzing sound.

  

  Click on the picture above. The sound you hear is made by the reed as it vibrates.

• Click on the following resonant chambers. You'll hear what the duck call sounds like played through each chamber. Compare the sounds. The duck call is attached to the right side of each plastic chamber.
  • AH
  • EE
  • EH
  • OH
  • OO

• Compare the shapes inside these models with the pictures shown here. Each picture shows the shape of your vocal tract when you say a different vowel. We've reproduced the plastic models next to the diagram for your convenience. Note that while the plastic models are straight, the vocal tract is bent almost 90 degrees in the middle.
  • AH
  • EE
  • EH
  • OH
  • OO

What's going on?

The chamber of each plastic model is shaped like your vocal tract - the cavity formed by your mouth and throat when you speak. Each time you say a different vowel, you change the shape of your vocal tract. That's why each model is a little different from the others. The plastic chambers pictures are aligned similar to your vocal tract with the vocal chords (duck call) at the bottom and the lips at the top.

At this exhibit, a puff of air from a bellows makes the duck call reed at the end of a hose vibrate, just as the air from your lungs makes your vocal cords vibrate. Like your vocal cords, the vibrating reed produces a complex sound composed of many different pitches.

Like your vocal tract, the plastic models shape these complex sounds into particular vowel sounds. When a complex sound echoes from the walls of the plastic cavity, some pitches are reinforced and some are not. It is the reinforcement and cancellation of certain pitches that changes the squawk of the duck call into a recognizable vowel sound.

Here's a bonus sound from the exhibit!