This applet lets you select one or more overtones of the A string (second to lowest) on the guitar and hear them. Java JDK 1.1 only supports 8-bit 8 kHz µ-law sound files, which don't sound all that great. In addition, there is no way of insuring that multiple sound files are played synchronously yet. So sounds made with multiple overtones (the whole point of this applet) sound kind of stupid. When Java sound support in browsers is improved (JDK 1.2) I'll improve the applet accordingly.
Right now, all the sounds have the same wave amplitude. Real overtones, of course, get weaker as you go higher in frequency. If I figure out how, I may add a volume control to each sound so you can synthesize your own overtone spectrum; again, Java needs better sound support for that to sound good.
The first time you play a sound, the audio files are downloaded over the net, so it will take a while before you hear anything. After that, those sounds are played from your local cache. You have to wait for a network download each time you pick a new sound. So be patient.
One interesting thing you can do with this applet is make a sound with the fundamental missing. The fascinating thing is that you can still hear the fundamental, because when two neighboring harmonics mix, they produce a fundamental in what is called beats. Try selecting only 220, only 330 and then 220 and 330 Hz together, for example.