- #1
greypilgrim
- 582
- 44
- TL;DR
- Why are the even-numbered overtones not suppressed?
Hi.
I have a wooden organ pipe with removable stopper and wanted to confirm the theoretically predicted spectra using a smartphone app. The formulae for the fundamental frequencies for the open and stopped cases work quite well, with the stopped pipe being about an octave lower.
However, theory also predicts that the even-multiple overtones should be absent in the stopped case (or at least clearly weaker than the odd ones). The spectrum does not exhibit this at all, I can clearly see all multiples of the fundamental with no clear pattern for the amplitudes. Same with a clarinet (which should behave like a stopped pipe as well); and I also used different apps and an iPad at some point.
Of course real instruments do not behave ideally, but I observed no indication of suppression of even-multiple overtones at all. Why?
I have a wooden organ pipe with removable stopper and wanted to confirm the theoretically predicted spectra using a smartphone app. The formulae for the fundamental frequencies for the open and stopped cases work quite well, with the stopped pipe being about an octave lower.
However, theory also predicts that the even-multiple overtones should be absent in the stopped case (or at least clearly weaker than the odd ones). The spectrum does not exhibit this at all, I can clearly see all multiples of the fundamental with no clear pattern for the amplitudes. Same with a clarinet (which should behave like a stopped pipe as well); and I also used different apps and an iPad at some point.
Of course real instruments do not behave ideally, but I observed no indication of suppression of even-multiple overtones at all. Why?