You can Drag & Drop your own mp3 file to play instead of the sample track. (Drag & drop will not work if you open webpage from your harddrive [file:/// protocol], because of Chrome's security restrictions. Try live demo instead.) By selecting a part of the frequency chart, you can filter different frequencies in real time. Press spacebar to reset frequency filter.
Canvas is used for rendering animations and Audio API for reading live audio from played track. Developed and tested in Chrome 18.
You can try live demo right away. It's automatically pulled, compiled and uploaded to the server every hour, so it reflects current state of this repository.