All my evidence is anecdotal, but I'm continually surprised by how little people who are under 30 understand about the nature of sound. As consumer electronics have done a better job keeping the details of music reproduction "under the hood" (especially with iPods and laptops), many listeners have lost contact with how the music goes from its source (digital files or analog LPs) to actual sound moving through the air. Does it matter? Not at all. I don't see people enjoying music any less. But for someone who has long been interested in the nitty gritty of sound, the changes are worth noting.

-=-=-=-As a high-end-audio-obsessed teenager growing up in the 1980s, I regularly read magazines like Stereophile and Audio. It was near the beginning of the CD era, and these publications were grappling with a big question: Do CD players really sound different? If you're talking turntables and cartridges-- devices meant to extract sound from tiny grooves and which involve a tremendous amount of physics-- it made perfect sense that two set-ups would produce noticeably different results. But hi-fi magazines had trouble with CD players because when two machines are extracting the same patterns of 1s and 0s, there was a real question of whether they could be distinguished.

One thing that was not in question, especially in the early days, is that CDs sounded better than LPs. Hi-fi magazines, especially then, were notorious for their number-crunching. Reviews of gear would include graphs that showed the frequency range of the sounds produced, measurements of things like channel separation (how much the information from the two stereo channels could be kept isolated from each other), signal-to-noise ratio, and dynamic range (the difference between the softest and loudest sounds the source was capable of reproducing). And every possible measurement of the sounds-- which are, after all, vibrations in the air that are quantifiable-- suggested that CDs were superior to LPs. There were still some holdouts, especially among those who had spent thousands of dollars on turntables, but the consensus was that CDs had gone a long way toward "solving" sound.

Of course, when you listen in on casual discussions of sound in 2013, you often hear that "LPs are back" because they "sound better." This has happened, in part, because "digital audio" is now considered as a monolith. In the time that the dominance of CDs started to erode around the turn of the millennium, we've come to understand the wide range of how mp3s can sound-- how cymbals on a circa-2002 128k mp3 sound like a pixelated wash compared to a 320k mp3, for example. But since these low-quality files were thrust upon people in the name of convenience and file size, certain associations regarding digital audio as a whole began to develop among a subset of record connoisseurs. For some, "mp3s are cheap and bad" turned into "digital audio is cheap and bad compared to LPs."

One of the often overlooked facts about LP reproduction is that some people prefer it because it introduces distortion. The "warmth" that many people associate with LPs can generally be described as a bass sound that is less accurate. Reproducing bass on vinyl is a serious engineering challenge, but the upshot is that there's a lot of filtering and signal processing happening to make the bass on vinyl work. You take some of this signal processing, add additional vibrations and distortions generated by a poorly manufactured turntable, and you end up with bass that sounds "warmer" than a CD, maybe-- but also very different than what the artists were hearing in the control room.