Introduction: Balloon Trombone

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This is the trombone for those that can't afford the brass. It also works great for the straw enthusiast, scientists of sound, arts-and-crafts-drawer musicians, and budding clowns.

There's something great about making your own instrument, as you can see all the parts that come together to affect sound. In making this, you get membranes, vibration, resonance, and variables to adjust that all go into making a sound that only a rubber chicken's mother could love.

  • What: Balloon Trombone!
  • Concepts: resonance, music, sound, vibration, pitch, wavelength, frequency
  • Time: ~ 15 minutes
  • Cost: ~ $0.50
  • Materials:
    • 1/2" PVC pipe
    • 1/2" PVC end cap
    • Balloon
    • Rubber band
    • Three skinny flexi straws
    • Larger straw (that slides easily over flexi straw, can find at fast food restaurants)
  • Tools:
    • Drill

Let's get tooting!

Step 1: Make a Membrane

Every good wind instrument works by something wiggling back and forth. In this particular case of fine art, it's a balloon.

Cut the top of your balloon and stretch it over one end of the PVC pipe. Use a rubber band and go around twice or three times to keep the balloon stretched tight over the top. It functions pretty well as a mini-drum already!

Step 2: Mold a Mouthpiece

You'll be making sweet (well, not so sweet) music in no time!

Just below the skirt of the balloon, drill a hole that's approximately the same diameter as your flexi-straws. Then cut one of the flexi-straws down so both ends of it are of approximately even length.

Insert one end through the hole so that the straw is pushed partway into the tube. If you have any gaps around the straw, use some hot glue to touch up.

Step 3: Cap With a Straw

Press on the PVC end cap on the side opposite the balloon. Drill a similar sized hole off-center in the end cap. Cut two flexi-straws such that you are saving only the long leg of them without the flexible part.

Put one of the straws aside for the next step, and press the other into the cap hole. Push it forward such that it is making contact with the balloon, and press it just a bit beyond so the balloon is raised by it.

This straw creates an air seal until enough air pressure builds up from the mouthpiece to cause the balloon to expand and let air through the straw in the end cap. The vibration of the balloon back and forth mixed with the resonant frequency of our straw length is going to make our sound.

Almost ready to jam!

Step 4: Add a Support and Slide

Take your second length of cut flexi-straw and slide it into the other. This lengthens the tube length and already will change the pitch. Then slide over the larger straw which is going to act as our trombone slide. By adjusting this length, we'll get different pitches from our instrument.

Step 5: Trombone Like a Champion

Well it's not going to play itself. And so with a little extension and retraction of the slide, you can hum out any old tune in the key of squeaky.

Experiment with tube length or with using different types of straws. What happens if you make holes in the sides of your straws instead? What other material could you use besides a balloon and how will it affect the sound? If you want to explore the science of sound in columns, this is a great primer.

Keep playing, keep changing it, and as always, keep exploring. :)