Here is the circuit in action:

Going Further

You may change either the SCALE variable or even the entire calculation of the frequency freq. There is nothing you can do to "break" the sound values generated to feel free to vary the numbers generated, the time the tone is generated, and the delay between tones.

You can generate precise notes by selecting the correct frequency. Which notes correspond to which frequencies may be found at http://en.wikipedia.org/wiki/Mathematics_of_musical_scales