Dr. AIX's POSTS — 11 September 2014


As many of you are aware, my friend Scott Wilkinson (the Home Theater Geek and editor in charge of AVS Forum) and I concocted a casual test to see if users equipped with high-resolution audio capable playback systems could perceive a difference between a standard resolution, CD spec audio selection and the exact same track in real high-resolution (96 kHz/24-bits). It was never intended to be a definitive or scientifically rigorous comparison but we felt it was worth doing. One of the reasons is because many HRA doubters point to the Meyer and Moran study that was written up in the AES Journal as proof that human listeners can’t distinguish between a 44.1 kHz/16-bit down conversion of a “high-resolution source” (they are not alone in reaching this conclusion).

It surprises me that all of the studies that have done these comparisons start with source recordings that don’t contain any fidelity above that of a compact disc. I’ve written about this previously in a post of two. So Scott asked whether I would be interested in using a few of my tracks (which actually do contain better than CD fidelity) in a non-rigorous test on the AVS Forum. It took a little work to figure how we would prepare the files and present them to the AVS readers, but we figured out a scheme and posted the files. Some of you may have gotten involved and submitted your results.

Scott collected all of the submissions, did some statistical analysis, prepared some graphs, and came to some preliminary conclusions. And things seem to confirm that when listeners with high-quality playback systems listened to real HD-Audio tracks, they were able to identify them 85% of the time. Here’s a quick summary of the results. You can tune into the Home Theater Geek show later today (9/11/2014) and hear an hour-long discussion about our little study.

The first thing that Scott did was divide listener’s system into two groups. There were those that were considered HRA capable and those that weren’t. People were asked to describe their equipment and provide specs if possible.

Here’s a graph showing the success rate for HRA and Non-HRA capable systems.


Figure 1 – This is a graph showing the number of correct responses for HRA systems and non-HRA systems. [Click to enlarge]

The red bars are the non-HRA responses. Notice that the x-axis ranges from “No determination”, meaning the listeners couldn’t tell any difference, to three, which was the number of tracks in the test. The blue bars are those with HRA capable systems. These folks did much better. The non-HRA systems results were around 50%, indicating no ability to tell the difference.

However, those with good systems (and seemingly good ears) faired much better. They average about 85% correct in the test…statistically significant.

Here’s another chart showing the success rates for each of the individual tracks.


Figure 2 – Accuracy by track. [Click to enlarge]

This test involved a very limited number of participants and was done by individuals in their own homes. We make no claim that the results are meaningful or answer the question. But it is encouraging that with REAL HD-Audio content, we got results that agreed with the fidelity of the source files.

I’m seriously looking to do a rigorous test using JBL M2 Studio Reference Model speakers in my studio with my state-of-the-art equipment. I want 500 participants from all sorts of backgrounds. We’ll see what happens then.

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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.

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