None of the included albums recorded before 1996 register above DR9, helping illustrate the trend of increasing audio levels on commercial masters -- commonly referred to as "The Loudness War."
"I talk about it as a myth because it's based on this misguided idea that louder is always better," says Shepherd. "If you play people two versions of the same thing, chances are they'll pick the louder one. But that only works if you can keep turning it up forever, and that's not true in any real world situation, especially not in digital audio where there's this brickwall ceiling you can't go past."
The issue is not new -- Shepherd notes that the Beatles tried to compete with the loudness they heard on vinyl Motown releases -- but he identifies a turning point in the late 90s with the advent of CDs. As engineers began overusing techniques like dynamic range compression to compete for louder masters, sound quality suffered.
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"Beyond a certain point, it sounds flat, lifeless, has less of an emotional impact, and can even sound crushed and distorted," Shepherd says. "Unfortunately, that's where a lot of mainstream pop and rock is at."
There may be hope on the horizon. As YouTube joins platforms like Spotify and iTunes Radio in employing loudness normalization to even out track volumes, Shepherd believes artists and engineers will soon realize the audio arms race is "pointless." He also cites recent albums like Daft Punk's Random Access Memories (DR8) and Jack White's Lazaretto (DR10) that were commercial and critical successes despite employing conservative compression levels.
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"They prove that you don ’t need that loudness," he says. "With all this normalization coming in, the ones that are still super crushed are just not going to sound good in that environment and they'll figure it out. I’m optimistic in that sense, but right now the worst stuff is sounding worse than ever."
Check out Shepherd's infographic below and full post here.