Ohm's law of hearing states that our brain's do not process phase information for slowly varying sounds but does respond to changes in amplitude and frequency. Listen for yourself. (It will take a few moments for the sound to load.) Move the red cursors to several places in the graph and verify that the waveform is drastically changing shape.
This applet requires Java 1.1 and a sound card. The highest frequency that can be produced without aliasing problems is ~3500Hz. This demonstration was created by Dan Boye.