Here! The third applet on this page allows you to turn individual harmonics in the sound on and off:
http://www.jhu.edu/signals/listen-new/listen-newindex.htm
The only problem with it that it doesn't allow you to choose amplitude of said harmonics, which makes them too loud. You can not simulate a flute or a clarinet for example. And you can not change the base frequency (not a hammond organ), which make make it a bit harder to demonstrate the blending of harmonics into one timbre. But at least it's something, and it is online.
And a bonus: an applet that lets you to compare different tunings (temperaments), such as equal, Pythagorean, just, as well as several historical ones.
http://leware.net/temper/js/acc.htm
http://www.jhu.edu/signals/listen-new/listen-newindex.htm
The only problem with it that it doesn't allow you to choose amplitude of said harmonics, which makes them too loud. You can not simulate a flute or a clarinet for example. And you can not change the base frequency (not a hammond organ), which make make it a bit harder to demonstrate the blending of harmonics into one timbre. But at least it's something, and it is online.
And a bonus: an applet that lets you to compare different tunings (temperaments), such as equal, Pythagorean, just, as well as several historical ones.
http://leware.net/temper/js/acc.htm
