I have visited many sites and I have been impressed with how thorough many analysts are when it comes to comparing the Mp3, VQF, and AAC formats. Although I have been impressed, I have rarely been enlightened. First of all, Mp3, VQF, and AAC all produce different sounding files.
Data is cut away from the original file in order to produce a file similar yet a lot smaller.
All three of these formats use acoustical algorithms designed around the human ear. Frequencies and sounds that are not heard by the ear are eliminated. Each audio format handles this differently. My control test is listed below. All encoded songs are the encoded directly from the original WAV at 44 kHz stereo.