Audibility of "typical" Digital Filters in a Hi-Fi Playback
Reply #395 – 2014-11-20 22:52:00
ABX is just one method that has its flaws. Them are fighting words for some here! We want to see reliable, valid, objective, reproducible ... evidence for any claim. For any claim? How about giving me a link to one that has passed all of those here so that I get calibrated.Neither of these are given by posting ABX logs, so there is some faith involved in trusting the person and logs. Well, do we get to say Meyer and Moran's test reports are not reliable? Or do we take it on faith that it is because it had negative outcome? Again, I am trying to get calibrated. Let's say you don't trust the person. What then? He has to get a live witness? Why on earth would he want to go through all that trouble to convince you? What is in there for him to have an anonymous poster be satisfied in this regard? And why do you post under an alias? Shouldn't I be able to examine your history and who you are in judging your opinions and any test results you put forward? You have mine. How come you are afraid of transparency on your part?So what happens is not only skepticism against the original claim, but also the claim that the ABX log is genuine if the result is surprising. Your skepticism is due to lack of experience and knowledge. You can't turn that around and put the work on me to prove you wrong. We have peer reviewed tests in the form of Stuart's tests. We also have peer reviewed tests in the form of Meyer and Moran. In neither case will I remotely go to the place you are, questioning the integrity of people. Run these tests yourself. See if you can pass them. There are people on AVS Forum who shocked themselves after following me lead and carefully listening, found differences reliably. Until you demonstrate that you have done that, your suspicions are not an issue I worry about.(Who cares if someone fudged at 128 kbit mp3 ABX log, right? We know that at this bitrate transparency is not given.) Oh I would. If they cheated I wouldn't want to have anything to do with them in anything. I have little patience for people with lack of integrity. Now what if we have many people trying to reproduce the result but failing, and a few that also claim to have heard differences? These people are either: - cheating as well - hearing some artifact of their system that is not related to the actual comparison - have some anomalous hearing (e.g. psychoacoustic models of lossy encoders expect normal hearing) ... - have better hearing than everyone else (which you boldly admitted to do not) and genuinely hear a difference Did I miss something important? Of course. You missed the most important one: training. Are you really not aware of the concept of trained/expert listeners? You think anyone who does better has better hearing? How come with the same hearing ability I went from not hearing compression artifacts to outperforming all but one person in my entire career at Microsoft? The other major thing you missed is knowledge of the technology in question. I know what to listen for. When I took David's test I quickly zoomed in on the right note and the game was over. If you don't know that, you be lost in the woods when it comes to dynamic distortion. The difference may be there and audible to that person but if you don't know where it is in a 3 minute song, good luck finding it by randomly clicking here and there. There is a science to what is relevaing and what is not. Let me give you a real life example. The year is 1999 or early 2000. The music industry is up in arms about piracy. It forms a consortium called SDMI chaired by Leonardo whom you may know has chairman of MPEG to remedy that situation. One of the things they went after was adding audio watermark to DVD audio. They put out a call for proposal and Microsoft Research put one that they were working on forward. I hear about them doing that just before submission. I ask them to let me listen to see if the mark is transparent (big deal as far as acceptance by the labels). They assure me that they had done their listening tests and no one could tell the difference. I ask them to humor me and give me the tracks which were supplied by the labels. I don't know how much you know about audio watermarks but the concept is data hiding where the encoder attempts to find segments where masking would easily cover the toggling of the bits. Back to the story, they files were 24 bit 96 Khz and 3+ minutes long. I listen and I can't tell the difference. Bothered , I try harder and all of a sudden I detect something in a fraction of a second. It was just a transient that didn't sound right to me. I go back to the Microsoft Research manager and tell him that I thought I had found the difference. With disbelief, he asks me for the timecode where I heard it. I give it to him in seconds and milliseconds . The reaction was golden. He comes back after a bit and says I had indeed found it and was a bug in the code! They fixed it and all was well. This is what training, critical listening ability and technical knowledge enables. To people without those attributes, it comes across as something impossible. But with objective confirmation of the bug in the code, you can take what I said to bank. By the same token, unless you can demonstrate to me that you are an expert in this area, your incredulity I am afraid has no weight or importance to me. The above is one of the most important lessons here. We have proven beyond any doubt that the above skills exist and you cannot take your listening results as a measure of whether someone else can or cannot hear small distortions. This is why I don't care what Meyer and Moran found. They did not have critical listeners so their results don't apply to me. I will stop here and encourage you to go and take these tests. Try hard to pass them. You might, just might be able to do that. If so, you will learn something valuable.