Would you like to feed your audio system with signals equivalent to what the artist, producer, and mixing engineer heard in the studio? For most people, this is a no-brainer. Why would you not want to hear what the pros heard? And on that basis, a new generation of music players, USB DACs, and other high-resolution audio products is now on the market, seeking open ears and open minds. You'd think this would be cause for celebration. But a small cadre of rigid ideologues are not celebrating. They're insisting that there is no audible difference between CD-quality audio and high-res audio. They bought Perfect Sound Forever, the ancient Compact Disc marketing slogan, hook, line and sinker. Infinitely condescending, the Perfect Sound Foreverists claim to have science on their side and dismiss any other point of view. But the latest science flatly contradicts their long-held dogma.
For non-techies who just wandered into this war of ideologies, CD audio is a 16-bit, 44.1 kHz format. That means a string of 16 zeroes and ones is transmitted 44,100 times per second. High-res audio is generally meant to refer to 24-bit, 88.2 kHz (and up) formats. The theory is that a longer string of bits, transmitted at a higher rate, translates into higher quality. In practice, to my ears, sometimes the difference is audible and sometimes it's not. A lot depends on the character of the original content, the resolution of the files used for mastering, and the quality of the mastering job. But I've heard enough great-sounding high-res audiosome demos staged by manufacturers, some by myself at hometo be pretty certain this new world is worth exploring. So it would be a shame if the Perfect Sound Foreverists succeeded in undermining high-res audio just as it's reaching a new generation of potential audiophiles.
And that is just what they are trying, perversely, to do. I once published a blog asserting that CD Quality Is Not High-Res Audio. A typical Perfect Sound Foreverist responded: "This is the assumption of all too many audio dilettantes who do not understand the engineering and physics supporting digital audio in general and the CD Redbook specification in particular. In fact, the evidence does not support the contention that there is an audible difference between CD and the so-called 'high resolution' audio formats, which differ from CD by using longer word sizes and sampling rates than CD."
The evidence cited over and over in favor of the Perfect Sound Foreverist viewpoint is a study by E. Brad Mayer and David R. Moran presented to the Audio Engineering Society in 2007. The title is Audibility of a CD-Standard A/DA/A Loop Inserted into High-Resolution Audio Playback. The abstract says: "Claims both published and anecdotal are regularly made for audibly superior sound quality for two-channel audio encoded with longer word lengths and/or at higher sampling rates than the 16-bit/44.1-kHz CD standard. The authors report on a series of double-blind tests comparing the analog output of high-resolution players playing high-resolution recordings with the same signal passed through a 16-bit/44.1-kHz 'bottleneck.' The tests were conducted for over a year using different systems and a variety of subjects. The systems included expensive professional monitors and one high-end system with electrostatic loudspeakers and expensive components and cables. The subjects included professional recording engineers, students in a university recording program, and dedicated audiophiles. The test results show that the CD-quality A/D/A loop was undetectable at normal-to-loud listening levels, by any of the subjects, on any of the playback systems. The noise of the CD-quality loop was audible only at very elevated levels." While access to the study is paywalled for non-AES members, you can buy it for $20 here.
Seven years later, a new study was submitted to AES by Helen M. Jackson, Michael D. Capp, and J. Robert Stuart, all of whom are associated with Meridian Audio Ltd. in the U.K. The title is The Audibility of Typical Digital Audio Filters in a High-Fidelity Playback System. The abstract says: "This paper describes listening tests investigating the audibility of various filters applied in high-resolution wideband digital playback systems. Discrimination between filtered and unfiltered signals was compared directly in the same subjects using a double-blind psychophysical test. Filter responses tested were representative of anti-alias filters used in A/D (analog-to-digital) converters or mastering processes. Further tests probed the audibility of 16-bit quantization with or without a rectangular dither. Results suggest that listeners are sensitive to the small signal alterations introduced by these filters and quantization. Two main conclusions are offered: first, there exist audible signals that cannot be encoded transparently by a standard CD; and second, an audio chain used for such experiments must be capable of high-fidelity reproduction." (Emphasis added.) Twenty bucks will get you a look at the study here.
So here are two studies undertaken with double-blind methodology, which the Perfect Sound Foreverists (and objectivists in general) insist is the scientific gold standard. They say a double-blind study is always right; they slam anything else as "pseudo-science." What could go wrong? Yet these two double-blind studies contradict one another. Only one of them can be right. But which one?
We might drill deeper into the details and discuss the different hardware, content, listeners, and testing practices. One aspect of the newer study that I find interesting is the Training section. I probably can't quote the paywalled material at length but I'll summarize. Jackson, Capp, and Stuart believed, based on preliminary data and feedback, that listeners needed time to prepare themselves for the task. So they implemented a three-phase training program that allowed listeners to familiarize themselves with the 200-second piece of music used for comparison, the filtering used in the test to distinguish CD-quality audio from high-res audio, and the test conditions. Only when listeners had prepared themselves in this manner did the actual testing move forward.
The conclusions? Listeners could hear the difference between 16/44.1 and 24/192. The filters and quantization used to downsample high-res masters for CD release can have a "deleterious effect." However, not all music reveals this loss of transparency. It is more audible with music having prominent echoes. This is roughly consistent with my considerably less scientific high-res listening experience: Sometimes I can hear the difference, sometimes I can't. Jackson, Capp, and Stuart also caution that, to ensure meaningful results, psychophysical tests should "minimise cognitive load," which presumably was the intent of their training procedure.
The new study is a win for high-res audiophiles. But it probably won't silence toxic ideologies. Nor will it be sufficient in itself to ensure the success of high-res content and equipment. The future of high-res audio is in the hands of artists, recording engineers, product designers, marketers, and enthusiasts. It's great that they now have a more compelling story to counter the rigidity, dogmatism, bitterness, and condescension of the Perfect Sound Foreverists. But they will also have to produce both compelling high-res content and the gear necessary to make it sing. And then current and future audiophiles will have to decide for themselves whether high-res audio is worth the investment. In the end, this battle is not about science. It's about music. Anything that brings you closer to music is a good thing. And having a virtual seat in the recording studio, hearing what the artist intended, is a great place to start.
