For the past few days there has been a stack of big steel pipes in the road
outside where they are installing a new gas main. These are steel pipes (I
guess) about 25cm in diameter and 12 metres long as measured by pacing them.
Great, I thought, we can observe reflection from the open end. This is done
by going "boh" into the pipe and listening to the sound bouncing back and
forth. Works well. Today I chanced to click my tongue instead of going "boh"
and observed an interesting effect. What I heard back was a sort of high
frequency "pew" sound, just as if the click had been dispersed, with the
higher frequencies arriving first. Snapping my fingers produced the same effect.
Now I thought that sound in air is non-dispersive. Any ideas?