This kind of question causes religious arguments among audiophiles. Now, I’m no audiophile, but I’ll call it a matter of taste that’s dependent on your ability to hear the difference.
I do want to clarify a couple of things. Audio CDs are not compressed. That’s the reason they’re limited to around one hour. If you actually do the math, 16-bit stereo at 44 thousand samples per second takes up about 700 MB of data. That’s the capacity of an audio or data CD.
That doesn’t mean the sound you hear wasn’t compressed.
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What is compression?
File compression is simply a way to replace data with less data. For example, a compressed file might replace a string of zeroes with a number indicating how many zeroes are really there. The compressed format might be smaller than the original format, but it can be reconstructed with 100% fidelity. I use the word “fidelity” specifically because it does apply both to audio and video as well as data.
When we talk about zip files maintaining 100% fidelity, for example, that means what you get out of a compressed zip file is exactly the same as what you compressed.
Audio and mp3 compression
The same is not necessarily true for mp3 or other compressed audio and video formats. Audio compression looks for things like frequencies out of the range of the human ear and says, “You don’t need to keep 100% of the data. You can get by with 90% and it will still sound good.”
If compressed correctly, some amazing mathematical transformations do a wonderful job of preserving the sound you hear when decompressed for playback. But when you listen to the audio file, what you’re hearing is not exactly what went into it – you just might not hear that there’s a difference.
Audio data can be extremely large. A recording studio probably uses multi-track recording at a much higher bit rate than is finally delivered to customers, so we’re talking about a lot of data. But when they compile the final tracks, they compress them into something more manageable.
One thing to know about compression is that it isn’t an either-or process. It’s a scale. When I compress audio I can determine if I want to compress a lot to get a smaller file at the cost of audio quality or compress less aggressively to preserve audio quality.
The problem is that we don’t know where recording studios specifically set the dial while they’re producing the final product. Compression is going to depend on the producers’ goal, their audience, their budget, and other factors, so we just don’t know what the compression rate is.
Fidelity and the difference between CDs and vinyl
But what a studio finally puts on a traditional audio CD will be exactly the same as what you’ll get off of it when you play that CD. While there may be some compression in how they produced the file, what they put on the audio CD is not compressed because the plain old audio CD format does not have compression.
In a way, the same is true for vinyl records as well. The studio went through many steps to create the record and each step had its own issues. For instance, you might hear tape hiss in some songs, depending on the quality and state of the tape recording and playback equipment used in the studio.
Some people hear it, some people don’t, some recordings have it, and some don’t. Whether it’s important or not depends on the listener and the kind of music or audio.
In reality, we’re really trading off different kinds of distortion and issues when we talk about digital versus vinyl or analog recordings.
Now, it’s true that compressed formats like mp3 do introduce some distortion. Just as studios determine quality when they compress, it’s easy for an individual to create an mp3 that has high quality and large size or low quality and small size. It’s just a setting that they choose when they create the mp3.
Digital music is here to stay
One more thing to consider is that how you hear audio will also depend on the device. For instance, I would be shocked if you could hear the difference using iPod-caliber audio equipment.
It also depends on how well you hear. I honestly can’t tell the difference. Admittedly, I have 55 year-old ears and as you get older, your audio acuity tends to decrease.
When I did buy CDs in my twenties, I was just enjoying the sound. I wasn’t doing an A/B test, comparing them against vinyl records, or trying anything like that. I was glad that the pops and scratches were gone and that I didn’t have to worry about bouncing my record player. And, yeah, I thought those “you might blow out your speaker” warnings were kinda cool.
But digital music is incredibly flexible and convenient. I buy all of my music now on Amazon as mp3 files and I’ve actually ripped all of my old audio CDs and created mp3 files out of those original uncompressed audios. Again, it’s convenient, it works for me, and I really don’t hear a difference. I just enjoy the music.