Both Apple and AOL have adopted AAC (aka MPEG4) for their new music formats. How does AAC stack up against MP3? Now you can find out for yourself.
Roberto Amorim has created 12 samples of music encoded at different frequencies using different methods, and you can listen to them without knowing which is which. Rate them based on what you hear, and the results will be published after the test concludes. You have until June 15, so hurry up and get listening.
Please be sure that you can take this test under the best conditions possible. High-quality playback equipment is preferred. On lower-quality systems, differences between samples can be hard to distinguish because they all sound bad.
You can take the test on Windows, Mac or Linux, but your results will only count if you are running Windows. The music samples are 47MB, and available via BitTorrent for the BitTorrent-savvy.