A private music tracker called REDacted has a good overview [0] on this subject (link should be SFW, and is on a different domain than the tracker itself). What.CD, before its demise, was the first I had seen demonstrating this, but older trackers (OiNK, Waffles.fm, et al.) may have also had it.
Objectivity aside, IMO the easiest way to tell when listening is paying attention to high-frequency sounds, especially hi-hat cymbals. Unless lossy encoders have gotten remarkably better since I last tried, there’s always a marked loss of shimmer / reverb on those.
Spectrals are easily the best method. It’ll give you a subjective idea, but it’s never going to be truly perfect with lossy encodes. If you’re looking at FLAC then you can tell pretty easily if something is a lossy transcode, but otherwise knowing if something is 192kbps vs 128kbps is going to be difficult. For really low bit rate reencoded as 320 that should be obvious on the spectrals, but it won’t tell you anything definitive beyond “well, it was a much worse bit rate previously”… which is useful, but only to a point.
Great post, thank you! I was expecting to see frequency blocks because of quantization, but I'm positively surprised that there are MP3 compression tell-tales like the cut-off and gaps.
Objectivity aside, IMO the easiest way to tell when listening is paying attention to high-frequency sounds, especially hi-hat cymbals. Unless lossy encoders have gotten remarkably better since I last tried, there’s always a marked loss of shimmer / reverb on those.
[0]: https://interviewfor.red/en/spectrals.html