[to Newman]
Most Atmos listeners never hear the studio master, only a compressed delivery codec. So how big is the difference in practice? The team at Immersive Machines hosted a double-blind 7.1.4 listening test with pro engineers comparing DD+, AC-4 and lossless PCM. The results were closer, and more revealin
www.production-expert.com
Thanks for finding and sharing this, much appreciated.
@krabapple's
analysis separates the wheat from the chaff, good job. The author, who co-designed the experiment, had a dominant interest in what the codecs did to the surround channels individually. As krabapple says, that is "
very much bullshit from a psychoacoustic perspective". After all, masking is the fundamental operating principle of lossy audio codecs (that's why, if one plays the difference file between an mp3 and its source PCM, the difference is shocking and horrendous no matter how high the bitrate), so the only valid way to evaluate a lossy audio codec is in totality. Not separately in parts.
In the end, the author's dominant interest destroys the whole experiment. How? Because they told the listeners when they were hearing A, when B, and when C. By the time listeners had completed the first musical selection, they had heard the surround channels solo, had heard the artefacts that way, and knew that A and B were lossy with 'audible artefacts' (solo). From that moment on, all the other musical selections were effectively fully sighted, with full prejudices established. Cover of blinding blown, experiment broken.
Assuming their conclusions are from summing all the musical selections, those conclusions will be fully invalid. It would be interesting to see the results of part 1 only (all channels on) of musical selection 1 only.
A pity. If they had stuck to all channels playing, the whole thing would have been much more informative wrt to audibility and preference.
”When I first listened to new albums on Apple Music or TIDAL on my living room home theater system, DD+JOC was exciting and filled the room with a big sound in a way that stereo simply could not do. But over time, the limitations of DD+JOC became more apparent. And when listening to DD+JOC in the more critical setting of a professional mix room, and with an uncompressed reference available for comparison, its limitations are obvious. The spatial distinctiveness of individual objects are blurred and the soundstage folds in”.
??? Are you unaware that the above quote is
not the conclusions from the experiment? It is, instead, the writer's pre-formed conclusion before entering the experiment, based on
his personal sighted listening experiences. In other words, it is an accurate description of the cognitive biases he had developed over time, reinforced and amplified with confirmation bias. A statement of prior bias.
If you are indeed aware, then it is quite unacceptable for you to deliberately try and mislead the readership like this.
What every listener with access to quality MCH system AND ability to critically listen to immersive audio was able to tell since years - that there is clear audible difference between DD+ and lossless Atmos, is now being slowly accepted - even if the only motive is to push new Dolby codec. I hope, we are going to see more tests like this [funded by Dolby ;-) ] as Dolby will push AC4 into streaming.
So the discussions should be really now about “How much do I care about MCH audio quality” rather than empty discussions about what should be audible or not. If you are not able to distinguish DD+ vs lossless Atmos - now you have the answer - either your critical listening ability is not good enough or the system was not good enough to show the differences [or both].
@Sal1950 - looks, like we will be getting even LOWER bit rates in the future ;-), as usual only reason is better quality for the end consumer.
Totally disagree.
@krabapple came to the right conclusions through the appropriate analysis: in
the intended use case of all channels playing together, lossy is difficult to differentiate from lossless
even in an A/B comparison carefully set up. Translating this to the much looser comparisons made in the home environment, pretty much everything is going to be imagined, with momentary rare exceptions. Subject to revision with better evidence.
Anyway, Tidal Atmos is in AC-4, (for loudspeakers not just headphones as krabapple mentioned) and yet you complain about the clear audible inferiority of lossy streamed Atmos.
What the experiment shows is that you have most likely been kidding yourself in your listening room when
you say, "
For me, lossy DD+ versus TrueHD isn’t even a close call — the difference is obvious, not subtle."
You seem to be completely biased on this question. With this latest claim you now have a
track record of announcing "we have proof" when we have no such thing, not even close. You have started with your sighted listening impressions, and doggedly set out to have them validated as generally factually true about the sound waves themselves. Why not be more open to the very strong possibility, drawing on the audio science of sighted listening, that they are dominated by sighted listening cognitive effects?
cheers
PS I don't have a penny in the pot either way. Don't make the mistake of thinking I have the opposite opinion to yours. I do feel, though, that blatant claims based on sighted listening deserve to be called out, and checked. And I am genuinely curious as to what the science is actually telling us, as it applies to us at home. And no, it's not a question of personal standards.
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