You might also want to try this version of the applet,
which has sound but requires Java 2.
This java applet demonstrates
Fourier series,
which is a method of expressing an arbitrary periodic function as
a sum of cosine terms. In other words, Fourier series can be used to express a
function in terms of the frequencies (harmonics) it is composed of.
To select a function, you may press one of the following buttons:
Sine, Triangle, Sawtooth, Square, and Noise. The function is
displayed in white, with the Fourier series approximation in red.
You can edit the function directly by clicking on it.
Full Directions.
More applets.
Zip archive of this applet.
Version 1.5, posted 3/1/05
java@falstad.com