Appreciating HD Audio

Bob O'Donnell
B. O'Donnell|06.25.15

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Bob O'Donnell
June 25th, 2015
Appreciating HD Audio
Sony HD Audio ComponentsThe annual Consumer Electronics Show held every January in Las Vegas is, of course, the granddaddy of all consumer-focused trade shows. Its impact on the consumer electronics and tech business is felt far and wide, and many people eagerly look forward to its return. In fact, so much so, that several years ago, the folks at the Consumer Electronics Association (CEA)—who put on CES every year—decided to start offering their own version of "Christmas in July" by hosting CE Week in New York City at the end of June.

This year's CE Week mini tradeshow and related activities was held this week (June 23-25) and saw the debut of some new TVs and other gadgets, as well as further discussion about some of the hot topics that were a big issue at this year's main CES show, notably high resolution 4K TVs and high-resolution audio.

As a lifelong musician, I've always had an interest in high-quality audio sources. From the early days of CDs and DAT (Digital Audio Tape), through SACD (Super Audio CD), DVD-Audio, and other multi-channel audio formats, I've been an early adopter and eager supporter of high-resolution music.

Not surprisingly, I've been following the discussions around newer high-resolution audio products and developments with great interest. Companies like Sony and Pono have introduced a wide range of new products that can play back high-resolution HD Audio files—from portable players to desktop hifi units to high-quality headphones with integrated DACs (digital-to-analog convertors). In addition, services like the beleaguered Tidal are attempting to offer a higher-quality alternative to the often massively compressed MP3 streams used by other popular music streaming services.

What I find interesting this time around is that higher-quality audio formats are being greeted with a fair amount of skepticism in the press. The general argument goes something like this: "I've done listening tests and can't tell the difference between compressed music formats and these high-resolution files. Besides, the human ear can only hear so much, so don't bother with any of these products and services because you won't be able to get any real benefits."

Sound familiar?

The difficulty is that there is some truth to what's being said. However, as with many things in life, the devil is in the details. Part of the problem is that you need to maintain high-quality equipment throughout the complete listening chain—from file to source device to output device, whether that's headphones or an amplifier and speakers—in order to hear the kinds of differences that high-resolution audio can offer. If you're plugging stock white earbuds into an iPhone in order to listen to Tidal streams, you'd be hard pressed to tell the difference between almost any kind of file format.

Even decent quality equipment isn't always up to the task because some of the differences can be very subtle—in some cases it's things like the overall soundstage, or how different sounds "sit" in the mix. Now, you can certainly argue that this is esoteric and beyond the needs and listening skills of most people, and honestly, I'd be hard pressed to argue with you. But think about it this way: if you're auditioning sets of speakers or comparing different headphones against each other, it's exactly these kinds of subtle clues and differences that you use to decide to buy one product instead of another.

An even bigger problem with all of the "high resolution audio is no better" arguments is that virtually all of the listening tests are done with popular music, for obvious reasons. But what most people don't know is that virtually all pop music is intentionally compressed to sound "better" to our ears. I don't mean data compression here, but rather audio compression, which is a process by which the dynamic range of the audio signals is basically "smooshed" together in order to avoid extreme volume changes.

A much fairer test for hearing the difference in high-resolution audio is to listen to music formats like classical, jazz or acoustic that use little or no audio compression because you'll be more likely to hear differences there.

But that's not the only problem. If you're listening to music in any format that hasn't been recorded and mastered (basically, mixed down to stereo) in higher resolution, you'll be hard-pressed to hear any audible difference between standard definition and high definition audio. It's kind of like trying to add resolution to a low-res digital image. Yes, there are some tricks to help you do it, but you're basically adding something that wasn't originally there.

In order to create a true high-resolution audio file, musicians and engineers have to go back to the raw source recordings (presuming they're recorded at high resolutions) and then specifically create a new high-resolution mix. Given the relatively small size of the audiophile, high-resolution friendly market, many don't feel it's worth the extra effort. Thankfully, there are some who do, and you're best bet for being able to really hear high resolution audio benefits is to listen to these kinds of source files on high-quality equipment.

Unfortunately, yet another problem is that there isn't any real consistency in labelling of these high-quality files. Most people assume that if they're listening to a 24-bit, 96kHz (or even 192 kHZ) FLAC file, then it's got to be "true" high resolution. But again, that isn't always the case. Yes, technically it is an HD Audio file, but it may not essentially be much better than a standard resolution file with a bunch of extra empty bits tacked on at the end of it.

The quest for high-quality audio is a never-ending one, and it's unlikely that this latest round of products and services will be the last. But one last thought for audio enthusiasts to console themselves with is that if you do make the plunge into HD Audio, you can be assured that you'll get the best possible playback quality of any format file you choose to play through your new devices. That's certainly worth something.
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