Audio Comparison: Putting MP3, WMA, And AAC Under A Microscope
Creating an audio compression codec is not an easy task, and neither is analyzing its results. Thankfully, there are tools today that help make this task easier.
CoolEdit provides a good frequency analyzer. Using the frequency analyzer, it becomes easy to tell the effects of each codec on the original audio track: 4.wav. I took a snapshot of the three encoded files at the same point in the track. This allows apples to be compared with apples.
The above picture is the frequency analysis for the original audio track "4.wav." The vertical axis is in decibels and the horizontal axis is in Hz. The human ear can hear between 20 Hz and 20 kHz.