Generate "Silence" so you have something to start with.
Change the view to "Samples." You can see how many samples make up the waveform on the lower status bar by rolling over the end of the waveform. Note: if you are having trouble doing this, go to the View menu, then Set Selection Format to "samples (snap to samples)". The number of samples you have selected will be displayed in the lower status bar.
Cut down most of the silence. Zoom in.
Repeat until you've cut the number of samples down to a power of 2 (64, 128, and 256 are good values.)
Now select the "Draw" tool.
Paint something with the mouse on the silence. A smooth, slow curve will sound "hollow" while a jumpy, irregular pattern will sound "noisy."
Make sure your sound is on, but keep it turned low for the next part. (This is so that if your sound wave sounds particularly unpleasant, your ears will be spared.)
Shift-click on the Play button to loop-play your sound.
