How does the wind organ in this youtube video work?

[theBEAST]

http://www.youtube.com/watch?v=AuYFcjBmMJ0&feature=relmfu

at time 34:35. He says it depends on how fast the air is flowing by? So does that mean the velocity of sound in the equation f=nv/2L change? How are the different sounds produced?

 

[Michael C]

It's not the velocity of sound that's changing, its n that is changing in the equation f=nv/2L. The different notes are different harmonics, corresponding to different integer values of n.