I made a few sound recordings where I struck a square metal plate with a wooden mallet. The address is http://homepage.lnu.se/staff/pkumsi/2FY808/ followed by the file name which is STE-xxx.wav, where xxx ranges from 007 to 020. For example http://homepage.lnu.se/staff/pkumsi/2FY808/STE-017.wav (not the best recording).

The recordings are in stereo. The signals originate from two pickup coils below adjacent corners of the square plate.

The are many ways to analyze the data files. For the spectrum shown on this page, I used Audacity to do the Fourier analysis, and then Graphical Analysis (now Logger Pro – students can get a copy of this software at home) to generate the plot. It might be that BaudLine is also a good tool.

Everyone can choose a different file. The spectra will not be the same, because I struck the plate in different places – can you deduce where? You are encouraged to cooperate and discuss.