Recent posts have challenged previous studies trying to establish whether high-resolution audio is perceptible. There’s also a lot of conversation about the same topic on a closed professional audio engineering list I belong to. I found Ethan Winer’s “high-resolution” examples lacking and Meyer and Moran’s study seriously lacking because of the content used. Not surprisingly, both of these gentlemen argued that I need to conduct a study of my own. While I was on the CEA audio board, I submitted a proposal to have them conduct a rigorous study. They weren’t interested although they did use some of my files for a comparison marketing survey. The participants listened through the files in a glass walled, conference room on a small scale system and not surprisingly, they couldn’t detect any differences.
I read a lot of comments by FB users saying they can easily detect the difference between and CD and high-res file. Or that HD music is “dramatically” better than CD quality. I doubt these claims.
What would a true test look like? Is the core question whether human hearing can consciously detect a high-res file from a downconverted version of the same file? We already know that there is greater fidelity (fidelity meaning more closely matching the source feed) in a high-resolution PCM file. The plots that I’ve provided in the previous few articles clearly shows the presence of ultrasonics and increased dynamic range. But can any listener with a good system listen to a standard-resolution file and a high-resolution file of the same recording and perceive any differences? It’s important that the only difference between the two files be the reduced frequency response AND the lower dynamic range. To keep the comparison fair, both files have to be level matched and otherwise be identical — same file size, same sample rate, and word length.
So here we go. I’ve uploaded 6 different tracks to my FTP site (1.22 gigabytes) in a folder called:
_Hi-Res_vs_Redbook CD Survey June 2018.
To get the credentials for the FTP site, please click on the FREE HD-AUDIO banner on the right sidebar or click here.
My process for preparing these files is as follows: I opened the original 96 kHz/24-bit PCM files into Adobe Audition. To create the Redbook version, I downconverted the high-resolution master to 44.1 /16-bits using triangular dither and noise shaping (which I’ve found to be the most neutral conversion process _ you may disagree. I open to other processes.). Then I upconverted the Redbook version to a new 96 kHz/24-bit PCM file. I analyzed the two versions to make sure the volumes and frequency plots are the same (except for the steep cutoff at 22.050 kHz) and the dynamic range was reduced as a result of the bit reduction. Take a look at the following illustrations:
This is the analysis for the original file. Notice the extended frequency response, the smooth ultrasonics in the spectrum, and the extreme dynamic range. [Click to enlarge]
Here’s the downconverted version at Redbook specifications. The hard cut at 22.050 is present, the spectra has a flat cutoff, and the dynamic range is 50-60 dB less! [Click to enlarge].
So I invite any reader to download these files (you may have to wait for the server to become available) and do your own listening comparison. Obviously, it’s pointless to cheat by doing your own analysis with Audition, Audacity, or Sound Mirror. What’s the point of doing this if you cheat? There 6 different selections labelled A or B. Simply let me know which of the two you believe is the high-resolution version and which is the Redbook downconverted one. I’ll tabulate the results after a few weeks and see what we get. It should be interesting. It would be helpful if you let me know about your system (headphones vs speakers), you listening environment, age, and level of training. I would also ask you to affirm in your email that you have not attempted to circumvent the protocol laid out above and that you have only listened to the files in making your judgement. Thanks.
Once you’re ready to submit your results, please visit The High-Resolution Challenge Results Page. You’ll be asked to fill in some fields on a form. Please don’t post these files elsewhere or post your picks. It would be great to get 100 people to participate. I’ll give a free AIX Records sampler to the first 10 people that send in their guesses (free shipping too!)
This is casual test and in no way is meant to be definitive. But using materials that have better fidelity than Redbook CDs might at least remove my primary complaint against previous studies. I look forward to hearing from those willing to participate. Thanks and have fun.