[2] G. Karwasz, E. Rajch, "Die Zauberflöte" http://lab.pap.edu.pl/~rajch/flet/, in Polish
[3] E. Rajch, G.P. Karwasz. "Thunder Drums" http://lab.pap.edu.pl/~rajch/multimedia/Drums.doc, to be published
Sounds are the easiest to detect wave phenomena. Human ear is able to recognize single instruments in a symphonic orchestra, by detecting harmonic components characteristic to an instrument, i.e. performing Fourier analysis. Fourier analysis even one hundred years ago was a difficult, mechanical task. So-called König analyser was a series of empty metallic spheres, resonating at characteristic frequencies. Ten years ago, digital oscilloscopes http://polly.phys.msu.su/~zeld/oscill.html were needed to do this same. Today it is free software and cheap microphone connected to the PC input.
Generators can be electronic circuits but then no didactics is inside: if we add new frequency, we (to our surprise!) find this frequency (!). We show that: 1) monochromatic generator, with slightly adjustable frequency are glasses with water [1], 2) up to 6 series of odd-like spectra can be obtained from a toy flute [2], 3) thunder drums show Bessel frequencies, open tube features, and reverberation [3], 4) three different frequencies can be obtained from an Al rod. 5) wave modulation can be done with two iron bells.
[1] E. Rajch, G. Karwasz, "Sparkling music", http://lab.pap.edu.pl/~rajch/kieliszki , in Polish
[2] G. Karwasz, E. Rajch, "Die Zauberflöte" http://lab.pap.edu.pl/~rajch/flet/, in Polish
[3] E. Rajch, G.P. Karwasz. "Thunder Drums" http://lab.pap.edu.pl/~rajch/multimedia/Drums.doc,
to be published