[1] This means that when an MP3 that was encoded at those bitrates is being played back, it is indistinguishable from the original PCM, and the compression is transparent to the listener.
Despite this, sometimes general consensus is formed for what compression options "should" provide transparent results for most people on most equipment.
Due to the subjectivity and the changing nature of compression, recording, and playback technology, such opinions should be considered only as rough estimates rather than established fact.
Judging transparency can be difficult, due to observer bias, in which subjective like/dislike of a certain compression methodology emotionally influences their judgment.
Such a confusion is widely present in the field of radiology (specifically for the study of diagnostically acceptable irreversible compression), where visually lossless is taken to mean anywhere from artifact-free[5] to being indistinguishable on a side-to-side view,[6] neither being as stringent as the flicker test.