The speed of sound in air is 340 m/s. (a) Find the fundamental frequency of a closed organ pipe of length 0.85 m. (b) Find the fundamental and the first two overtones of an open organ pipe of the same length. Solution: (a) Closed pipe: f1 = v/(4L) = 340/(4 x 0.85) = 340/3.4 = 100 Hz. (b) Open pipe: f1 = v/(2L) = 340/(1.7) = 200 Hz. Overtones are all harmonics: first overtone = 2 f1 = 400 Hz, second overtone = 3 f1 = 600 Hz. Note the closed pipe of the same length sounds an octave lower (100 Hz vs 200 Hz) and has no even harmonics.