Here is a better way to make flame sing: the pyrophone.

Using a well-constructed flame organ, you can hook up a keyboard to pipes which create a sound using fire. Just use a glass tube and insert a propane burner into one end of it. Soon, you will begin to hear a sound on the order of the resonant frequency of the tube. Set up a whole array of these, work out complex matters of timing and attack and decay of each note, and congratulations, your flames will be doing your bidding.

The pyrophone is well-documented, beginning with a late nineteenth century publication, and although few of these instruments are currently in working order, if you are interested enough to visit a node on singing fire, you may very well be the creator of the next -- provided you hear and discard the words of common wisdom thusly, "Don't play with fire, kids." Some more detailed information can be found under pyrophone.

Patience is all well and good, but propane and glass tubes are far quicker.