Audio DesignLine Blog | Audio Design Opinions and Analysis

June 25, 2008
Another shot fired in the "loudness war"
By Rich Pell

With all the recent negative attention that the "loudness war" - the music industry's tendency to increasingly limit the dynamic range of CD recordings of popular music - has been receiving lately it seems more music artists are beginning to try to do something to address it (for example, see Rolling Stone: Hi-Fi not dead after all). The most recent example is a new CD from a popular artist that's made directly from an LP master.

According to a recent column in The New York Times ("For Tom Petty Fans, the True Sound of Vinyl, Also Captured on a CD"), a new album from the group Mudcrutch, featuring Tom Petty, will include the LP-mastered CD packaged with the vinyl version of the album. Those who purchase the regular CD version of the album will receive a separately mastered product that, according to one of the album's producers, reflects "the realities of the marketplace" - presumably meaning it has a reduced dynamic range.

This is an interesting approach, but it does bring up a couple of questions. For example, I wonder if the LP-mastered CD, while perhaps not being unduly compressed (a good thing), might also reflect equalization and/or limiting in the master that was added to compensate for vinyl's inherent limitations (and which would be unnecessary - and detrimental - on a CD)?

That aside, why not make the LP-mastered CD available separately, rather than require listeners to purchase the LP package to get it? I checked online and didn't see this available as an option. Better yet, why not make both the regular and LP-mastered recordings available online as downloads?

While it's nice to see the "loudness war" being actively fought on several fronts, I doubt that much will come of efforts that are dependent on the recording and distribution of dying media formats.

Comments, questions or suggestions? Email me at rich.pell@verizon.net.

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June 18, 2008
MP3 player audio quality tests: Some surprises
By Rich Pell

The audio quality test results of several popular - and not so popular - MP3 players are compared in an interesting article on CNET's MP3 Insider. And the results may be surprising to some people.

In the article ("Audiophile MP3 players, by the numbers"), players from Apple, Creative Technology, and Sony, among others, were tested for frequency response, THD+N, and SNR using an Audio Precision ATS-2 Audio Analyzer, and then ranked by measured audio performance. The top two players were the Creative Zen and the Creative Zen Stone Plus.

The authors admit to being somewhat taken aback at this result - they had naturally expected the uber-popular Apple iPod to take top honors. I can't say I was surprised. I've written before about how while the iPod may win hands down in usability and style over other players, it may not necessarily be the best choice for "audiophile" sound quality (see "Why I don't own an iPod").

The authors go on to downplay the measured performance differences among the players, pointing out that they're hardly likely to be audible in the usual listening conditions in which these units are typically used. True enough, but it's also true that portable players are increasingly serving double-duty in docking stations to provide music in the home.

And some of us even use these players as portable/transportable secondary hi-fi systems - often along with high-end headphones and separate headphone amplifiers etc. - for when we're away from our primary systems. So subtle audio performance differences among the players can take on greater significance.

For the record, the top-ranked player among those tested - the Creative Zen - had the lowest measured distortion, with a THD+N of -82.27 dB (over 10 dB better than the iPod). The Zen's "frequency response deviation average" and SNR were on par (or even slightly worse) compared to some of the other top players.

To be fair, all of these measurements were taken from the players' headphone outputs and thus reflect, in part, the performance of the players' built-in headphone amplifiers. So the test results most likely won't reflect the performance enjoyed by those of us who choose to amplify the audio signal separately from a player's line output (if it has one).

Comments, questions or suggestions? Email me at rich.pell@verizon.net.

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June 11, 2008
Study: How does the brain separate audio signals from noise?
By Rich Pell

Some recent research may shed new light on how the human brain extracts meaningful signals from noisy acoustic environments. In an article published in the open-access journal PLoS BIOLOGY, researchers describe how they investigated the role of the auditory cortex in informational masking by recording the brain responses of listeners performing an auditory detection task.

Informational masking is distinct from traditional "energetic" masking, which occurs when a target signal is rendered inaudible by a competing "masking" signal(s). In informational masking, both the target and masking signal are audible, but are not perceptually recognizable to listeners.

The researchers used this effect to isolate brain responses that correlated with conscious auditory perception among listeners who indicated when they heard a stream of repeating tones (target) embedded in a stochastic tone background (masker). You can listen to the sound files used in the auditory detection test (below):

Example of a Target Embedded in an Informational Masker (236 KB MP3)
The Isolated Target of the Example (236 KB MP3)
The Isolated Informational Masker of the Example (236 KB MP3)

From the results of their study, the researchers concluded that conscious sound perception originates from within the auditory regions of the brain, but not from the initial cortical region where sound is processed. According to the press release, this study will likely affect future research in this area:

Because many previous neuroimaging studies have used simple stimuli in unnatural contexts, such as pure tones in an otherwise quiet environment, this novel study will influence future research investigations aimed at uncovering the neural mechanisms of conscious perception in natural and complex environments.

You can read the complete article online at the following link:

"Neural Correlates of Auditory Perceptual Awareness under Informational Masking"

Comments, questions or suggestions? Email me at rich.pell@verizon.net.

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June 04, 2008
Is MT9 the new MP3?
By Rich Pell

A new digital music format that's being described by some sources as the "new MP3" has been introduced by Korean company Audizen. The format, which uses "MT9" as a file extension and is being marketed as "Music 2.0," offers six channels of unmixed audio tracks - vocals, chorus, piano, guitar, bass and drum - that allows end users to control each track independently in playback.

According to The Korea Times, the format was selected as a candidate item for the new digital music standard at a regular meeting of the Motion Picture Experts Group (MPEG) in April. Audizen is expecting it to be formally selected as an international standard at the organization's annual forum in Germany in June.

The company says that Samsung and LG Electronics have expressed interest in including an MT9 player on their future mobile phones. In terms of content, Audizen is currently selling some MT9-compatible albums on its web site, and says that currently existing albums can be converted to MT9 files if they have a digitally re-mastered music source.

Clearly this new format will have some appeal to musicians and karaoke fans, but I suspect the MP3 file format is safe for now.

Comments, questions or suggestions? Email me at rich.pell@verizon.net.

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