Dr. AIX's POSTS — 22 December 2014


I have been highly critical of the study by Dave Meyer and E. Brad Moran on the “Audibility of a CD-Standard A/D/A Loop Inserted into High-Resolution Audio Playback”. Their AES paper has been quoted as “proof” that high-resolution audio is “not audible” because no one in their study group could identify a “high-resolution audio” vs. a CD specification version. My point has been that none of the content that they used during their project qualified a true high-resolution audio. As readers know, my definition means that it was natively recorded using high-resolution equipment at the time of the original sessions. If your definition includes older analog tape masters transferred to DSD 64, then you’ll agree with the study.

The purpose of the research was to determine whether the new SACD and DVD-Audio formats were worth the effort and cost. After all, if no one can tell the difference then why bother?

Apparently, the debate about the validity of the research continues. On a different high-end audio group, I asked a supporter of the Meyer and Moran study to identify a single track on any of the albums that contained any qualities that would qualify as high-resolution. I asked this because I know that every recording that they used during the test didn’t qualify as high-resolution. If the “high-resolution” sources didn’t have greater dynamic range or higher frequencies than 44.1 kHz/16-bit CDs, then the test was meaningless.

A response from one of the two researchers was posted on that site this morning. I have quoted it below:

“This whole discussion has been hijacked, Fox-News-style, by people who were forced to abandon their original claims and have been driven into a small corner of the territory they formerly occupied.

The original take on both “hi-res” formats was that for the first time they got digital right. The difference was said to be obvious not in the very highest frequencies but in the midrange, where we were supposed to experience for the first time true timbres; accurate and consistent placement of sources within the stereo image; reverb with accurate bloom and depth, and so on. The harshness supposedly inherent in then-current PCM hardware, laid at the feet of digital filters, jittery playback or whatever, was now banished; the ‘digital glare’ was gone at last.

Not only was all this about midrange material that even people my age could hear; it was not in any way dependent on extended dynamic range. It was all supposed to be audible with musical material in the upper 40 dB of the signal space, when played at normal levels. THAT’s what our tests were very well designed to find, and the big and important surprise was that once we equalized the levels and made the test blind, all those obvious differences vanished in the clear morning air.

So here’s an answer for those scornful people: You are arguing from the notion that there will only be a difference if there is musical material on the hi-res disc that exceeds the CD’s frequency and dynamic ranges. These are things that, as we pointed out and that you now admit, are very rare in recordings of any kind. In other words, there are very few discs on which one would expect any audible difference at all; none where the difference is easy to hear; and none where it is audible at normal playback levels. You have accepted the science behind all this! Welcome to reality. It appears our paper has had more influence than we could have dared to hope.

All that is left, now, is the question of sounds above 20 kHz. Everyone who argues that these are important has taken the research and its conclusions about human perception that were well established forty years ago, and thrown them out the window.

Meanwhile, there is one disc whose dynamic range exceeds the CD’s limit: The Hartke recording on Hilliard. When I discovered the properties of this disc, I turned the system way up and conducted a test using only the initial fade-in of the room sound. The difference was easily (and of course provably) audible. This is all in the paper, so, as has so often happened, those arguing that we didn’t use such a recording have not read what we wrote.

E. Brad Meyer”

I’ll parse the statement in tomorrow’s post but I find it interesting that the opening line is so self-referential (“people who were forced to abandon their original claims”). I haven’t changed my perspective. They’ve changed what they were testing (midrange?). I thought the test was to test the “audibility of high-resolution recordings” vs. CD spec audio. WE’RE learning now that this was not the focus at all.

And yes, I did read the paper…more than once.


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About Author


Mark Waldrep, aka Dr. AIX, has been producing and engineering music for over 40 years. He learned electronics as a teenager from his HAM radio father while learning to play the guitar. Mark received the first doctorate in music composition from UCLA in 1986 for a "binaural" electronic music composition. Other advanced degrees include an MS in computer science, an MFA/MA in music, BM in music and a BA in art. As an engineer and producer, Mark has worked on projects for the Rolling Stones, 311, Tool, KISS, Blink 182, Blues Traveler, Britney Spears, the San Francisco Symphony, The Dover Quartet, Willie Nelson, Paul Williams, The Allman Brothers, Bad Company and many more. Dr. Waldrep has been an innovator when it comes to multimedia and music. He created the first enhanced CDs in the 90s, the first DVD-Videos released in the U.S., the first web-connected DVD, the first DVD-Audio title, the first music Blu-ray disc and the first 3D Music Album. Additionally, he launched the first High Definition Music Download site in 2007 called iTrax.com. A frequency speaker at audio events, author of numerous articles, Dr. Waldrep is currently writing a book on the production and reproduction of high-end music called, "High-End Audio: A Practical Guide to Production and Playback". The book should be completed in the fall of 2013.

(12) Readers Comments

  1. Well I hear a difference between a (properly recorded) hi-res audio and a standard CD, not sure why there is so much heat in the debate.

  2. Mr Meyer chooses to subjugate rather than address facts. An all too common immature threader, who would rather mitigate their shortcomings by avoiding a fair and balanced discussion.

  3. My head is spinning with all the BS being thrown into this subject.

    1. Can ANY differences be heard between a Red Book and HD Recording original using at least 96/24 to define HD. Common sense would tell anyone that the original recording would have to be done at HD spec. Anyone who claims Analog Tape is good enough is just peddling snake oil on the subject.

    2 Complete playback chain must be up to HD spec standards.

    “Meanwhile, there is one disc whose dynamic range exceeds the CD’s limit: The Hartke recording on Hilliard. When I discovered the properties of this disc, I turned the system way up and conducted a test using only the initial fade-in of the room sound. The difference was easily (and of course provably) audible. This is all in the paper, so, as has so often happened, those arguing that we didn’t use such a recording have not read what we wrote.”

    So Mr Meyer, Using the necessary HD media and playback equipment “The difference was easily and of course provably audible” YOU CAN “hear a difference. To me that statement immediately supports Mark Waldrep’s and a large part of the audiophile communities position on the subject.

    • I’m going to parse the Moran statements today. However, you’re right. He dismisses the increased dynamic range of 24-bit HD-Audio and then goes on to us increased dynamic range to show that the content they chose was really high-resolution! The study was seriously flawed and the authors (and plenty of others) are still supporting it.

  4. Well hey, there’s nothing wrong with noticeably better midrange, ’cause that’s where the music is. No matter from what point in the chain the improvement comes, when we hear better mid-range, we hear better sound.

    But, part of any master tape grade playback is the revelation of LF and HF bandwidth not present on the typical consumer format. I certainly have found quite a few DVD-A’s, ( definitely including yours Mark,) and SACD’s that manifest these values.

    As far as the value of wideband reproduction exceeding the audible range, this is another old song that needs no further refrain; of course we want a wide margin of accuracy around the range with which we are principally concerned in order to ensure linearity in the region of concern. Merry Xmas one and all!

    • Happy holidays to you as well Craig. I don’t think anyone was claiming that the midrange of a PCM digital recording would improve by moving to high-resolution. At least none of the engineers that I knew at that time…or now.

      • What about all the audiophiles, i.e. the ones that matter? They were DEFINITELY claiming that SACD sound was vastly batter than CD sound in the ‘guts’ of the music, not the extremes. And many still do.

        • That the same group of “Golden Ears” that hear day and night improvements from their new $3000.00 power cables.?

          • Don’t get me started on the whole cable thing…the PFO reviewer that choose cables as the most important item in his system needs help.

  5. Having only superficial knowledge of the background of this debate / argument I can only say that Meyer’s comments above make sense; regardless of what they actually set out to prove originally or what people thought they set out to prove. A well recorded / mastered red book CD may only be differentiated from higher ‘resolution’ (how I hate this word) recordings / masterings by extremely subtle differences in HF and, under ideal conditions, by the noise floor. Which nicely fits with the theory. The rest is industry and ‘high-end’ press mumbo jumbo. I don’t think there’s much material disagreement here. Peace!

    • Not just HF-LF extension in hi-res recordings increases the sense of air and dimension in playback not commonly heard on typical CD.

      • I’m not going there Craig…this is exactly the stuff the Meyer and Moran (and other studies) have shown to be inaudible.

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