phsyics help?

Question

A drainage pipe running under a treeway is 28m long. Both ends of the pipe are open, and the wind blowing across one end causes the air inside to vibrate. A)if the speed of sound on a particular day is 340 m/s, what will be the fundamental frequency of air vibration in this pipe? B)What is the frequency of the lowest harmonic that would be audible to human ear?

Answer 1

The fundemental is 340/28 = 12.1 Hz This is sub-sonic.

The 2nd harmonic at 24.2 Hz will be audible (as will the 3rd, 4th, etc. harmonics if they are present).
.