I have a loudspeaker that is facing into a long cylindrical piece of PVC pipe of length L. The loudspeaker is sealed in so that no air can escape around the edges. The pipe is open at the other end.
The loudspeaker is attached to a signal generator and made to vibrate at frequency f.
In this configuration, should the system be modeled as a closed pipe or an open pipe? Or does the choice of model depend on f ?
My intuition is that the loudspeaker represents a displacement antinode (and therefore a pressure node), and so the system should be modeled as an open pipe (pressure nodes on both ends). The system would then resonate at frequencies where $L=\frac{\lambda}{2}=\frac{c}{2f}$. Is this a correct assumption?
If one were to place a circular piece of PVC with a small hole in the center across the face of the speaker, so that air is compressed inside a small cavity before being released into the pipe, would this reverse the scenario so that the speaker end becomes a pressure antinode?
Thanks in advance!
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