The Frequency Test program to the left uses uncompressed audio files and will take a little while to load. This program allows you to test your computer speakers ability to handle various frequencies. The frequencies are all expressed in sine wave forms. The Sawtooth will start a sweep from 20khz down to 20hz, back up to 20khz, and will repeat. Hit the "Stop Sawtooth" button to stop it. This will allow you to hear the full range of your speakers. The other buttons emit a single frequency for one second.
You may want to try and find the specifications the manufacturer gives for your computer speakers and do a comparison. It is always interesting to see if your speakers are performing as well as the manufacturers specify.