Our favorite demonstration for sound waves is to set up a compressional pulse on a horizontally stretched Slinky[TM]. One can easily watch the pulse move back and forth at a speed of the order of one meter per second. Watching this demonstration, it occurred to us that the same thing might happen in a steel pipe if you hit the end of the pipe with a hammer. The main difference is that the speed of sound in steel is close to 5000 meters per second. If you hit the end of a 10-ft (3.05-m) pipe, the pulse should take about 1.2 ms to go down and back, a time conveniently measured by an oscilloscope.