Path of the Wave:

Reed opens and closes (produces the wave made by the instrument and also vibrates at the natural frequency of the air tube)

Reflection of the wave when the air pressure changes (open holes and at the end of the tube i.e. when the wave reaches a change in air pressure, the wave is reflected back- similar to a wave reflecting off a rock.)

Sound wave reflects back and forth through the tube (standing wave)

   Frequency of the sound wave is dependant on the length of the air tube and the air pressure

   More complex than sin wave

   Standing Wave: reflects where air pressure changes at the end of the holes