Description: This whistle can be used to illustrate several concepts.
First, a comparison can be done between the frequency with the middle wood stopper barely in, and with it out completely.
(The closed frequency should be roughly twice as high as without the middle wood stopper) This shows the difference between a
two open end pipe and a one open end pipe.
You can also show that the frequency of a one open end pipe changes with the size of the air column by varying the length of the middle wood stopper.
Note: A new cardboard mouthpiece should be used each time.