Regarding mcc's wondering as to why no sound is produced when there is no variation:

It's really pretty simple. /dev/audio doesn't interperet each byte as a frequency or wavelength or any other representation of a tone. Instead, it interprets the data more like an amplitude. As you may remember from physics, sound is produced by vibration (usually, vibrating air). This means that sound is a wave. The energy in a wave is determined, primarily, by the difference in amplitude (the "height" of the wave, when graphed) between the peak and the valley. If you send a stream of the same byte constantly, you get no sound since there is no energy in the wave.

It'll take a little experimenting to figure out exactly how /dev/audio translates the bytes to amplitudes, but that's the general idea. (I think I just figured out what I'm going to waste MY weekend on...)