In addition to the standing wave which determines the pitch of the sound, there are additional waves formed which have lower intensities. These together will give the sound colour of the pipe.

Their wavelength compared with the wavelength of the fundamental sound is:
• a third, a fifth etc. in the case of a closed pipe
• half, a third etc. in the case of an open pipe

Their frequency compared with the frequency of the fundamental sound is:
• three-times, five-times etc. in the case of a closed pipe
• two-times, three-times etc. in the case of an open pipe
in accordance with the f= c / formula.
So the frequency of a closed pipe is the integral multiple of the fundamental frequency, while the frequency of the closed one is an odd number multiple of the fundamental frequency.