Artifact Training Page - analyzing the results Options

[GL1zdA]

I did some ABX testing using foobar2000 and the samples from ff123's Artifact Training Page. I managed to get 0.1% probability that I'm guessing on all of them except Sarah McLachlan's Wait (there were 3 of us who did the test and only one heard the difference here). Now I'm trying to analyze the artifacts that I have heard. I view the files in Audacity and Sonic Visualizer and look what differences correspond to the artifacts. But I can't see what caused the distortions in 41_30sec_scmpx128.mp3 and left-dist_q0.ogg - the waveforms look quite similar. On most of the other samples the differences where clearly visible or became clearly visible after applying a high-pass filter, but I don't know how to see the difference in these two. Any hints?