Mathematically speaking the sliders control the amplitudes of the overtones of the base frequency.
We offer Excel workbooks for different versions of Excel, but only for Microsoft Windows.
There is an additional example, working only under
Excel97.
This example demonstrates a Fourier
series where the Fourier coefficients form a geometric progression
If you like what you see, you also may want to go to Erich Neuwirth's Spreadsheets in Education Home Page.