Lesson 10 of 15
Open Pipe Harmonics
Open Cylindrical Pipe
A pipe open at both ends (flute, organ open pipe) has pressure antinodes at each end. The resonant frequencies follow the same formula as a string:
f_n = rac{nv}{2L}, quad n = 1, 2, 3, ldots
- n — harmonic number
- m/s (speed of sound in air)
- L — pipe length (m)
All Harmonics Present
An open pipe supports all integer harmonics — the same as a string. This gives it a bright, rich timbre (flute, recorder, human vowels).
Changing Pitch
Halving the pipe length doubles the frequency — one octave up. This is why flutes are shorter than tubas.
| n | L=1 m | L=0.5 m |
|---|---|---|
| 1 | 171.5000 | 343.0000 |
| 2 | 343.0000 | 686.0000 |
| 3 | 514.5000 | 1029.0000 |
Your Task
Implement openPipeMode(n, L) returning the nth resonant frequency ( m/s).
Run the code to hear the fundamental and second harmonic of a 1-metre open pipe.
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Click "Run" to execute your code.