Straw Oboe Physics

1. Straw Oboe Physics

2. Straw Oboe A straw oboe is a double-reed instrument made simply with a straw and scissors. Many lessons can be taught about sound, waves, music, the ear, standing waves, etc. from the construction and use of the instrument.

3. Straw Oboe Construction First, let’s make a simple straw oboe with the thin drinking straw. Flatten one end of the straw and cut off the corners. Press down with your lips a little bit as shown and blow.

4. Straw Oboe Physics Air passes between the “reeds” creating an area of low pressure The reeds close Air passing over the closed reeds causes low pressure outside and they open Repeat

5. Straw Oboe Demonstration How does the length of the oboe affect the note that it plays? Is there any way to create the same effect without trimming the straw?

6. Can it Be Louder? The “loudness” of a sound is a result of the difference in pressure of the high pressure and low pressure areas of the sound wave. When the sound wave suddenly comes out of the end of the straw, the loudness decreases greatly. If we add a horn to make the release gradual, it will become much louder. High Pressure Low Pressure

7. The Bigger, the Better! http://www.exo.net/~pauld/summer_institute/summer_day11sound/Reflections_on_an_open_end.html

8. Now Let’s Play in a Band! First, we need to make some instruments to play notes. The equation for length and frequency (for thin tubes): Length = (Speed of Sound) ÷ 2(frequency) Speed of Sound = 34,320 cm/second So, a “G” is 785 Hertz, made with a straw of 21.9 cm. If you want to create the note, “G” you simply need to cut the straw so that it is 21.9 cm long. http://www.phy.mtu.edu/~suits/notefreqs.html

9. Musical Notes

11. Ode to Joy Melody: A A B C C B A G F F G A A G G A A B C C B A G F F G A G F F