The speaker is up and running with the play_melody example!! I tried the fade examples and they sounded horrible. I am not sure why. I connected the speaker with a 1K resistor and a 0.01mF capacitor. The speaker is from a pair of old external computer speakers (5 Watts 4 Ohms). They run very well off the Arduino power. My first iteration I was shorting out my voltage regulator because of a lack of ground. The speaker made some horrifying noises. But that problem is now solved. Now I will program some of my own notes for it to play. As for the processing end I created a random noise generator. Click on the applet to generate a random sound
Play applet
View source code