Why MP3s Are Not Yet Good Enough to Replace CDs

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    • mp3_vs_cd.jpgPictured above: a visual example of the difference between sampling at a high rate and a low rate forcing your brain to fill in the blanks. Photo of Radiohead at Coachella by Joe Puglisi.

    MP3 formatting has changed the way we listen to music, allowing for consumers to hold massive libraries of content without the hassle of a physical collection, or excessive digital storage. Compact Disc audio and MP3s are both digital audio– instead of creating sound waves with physical technology– like the grooves of a vinyl record– digital audio recreates sound waves with samples, a numerical value assigned to each frequency in the spectrum of what you’re hearing. Many people realize that there is a difference in quality, but don’t necessarily know why. The MP3 isn’t a replacement for CD quality, and here’s why:

    1. Size Matters

    CD audio is uncompressed. What that means is the average CD can hold 80 minutes of music, or about 700MB of sample data, and the typical track winds up being around 30-40 MB in size, which was certainly unrealistic for early portable devices with limited memory. The MP3 encoding reduces this file size to about 3-4MB per song, a much more manageable size for a digital library. But this reduction comes at a cost. There is even a difference between a 2MB song and a 4MB, even if it’s the same song, and the size differential seems negligible. Even when you “rip” a CD into iTunes or a similar program, depending on your settings, it converts the CD-quality files into a smaller format.

    2. Quality vs. Quantity 

    The reduced file size allows for a library of 10,000 songs or more on your iPod, but you sacrifice quality. MP3 audio is compressed in a way that removes certain samples from the file in order to trick your ears into thinking they are still there. The variety of bit-rates and sample quality (typically 128 kbps is considered “poor”, and 320 kbps is a high-quality MP3) will give you some variance in sound quality, but only the trained ear would be able to clearly hear the difference between a high-quality MP3 and a CD-quality file when listening on an average pair of headphones. That being said, when you look at the reasons for compressed audio existing, it becomes pretty clear that it’s a quality vs. quantity game. 
    3. Lack of Standardization

    While there are standardized formats (Amazon’s MP3 store, iTunes AAC files), the prominence of MP3 technology has led to a myriad of different file types, shapes, sizes, samples rates, and qualities. Simply obtaining a song in the MP3 format does not guarantee the compression or the clarity of the audio. Also, when an album is recorded, it goes through a final process called “mastering.” If this is done with the intention of having the best quality audio, even more might be lost in the compression process. Some artists have opted to master their albums with the intention of turning them into MP3s, in which case the CD “quality” audio may not sound all that spectacular.

    The average ear can still discern a decent quality file from one that has been poorly created, and if the numbers mumbo-jumbo doesn’t suit you, there are a few tricks to telling how much has been removed from the samples in your file.

    Things to listen for when judging the quality of your audio: 

    1. Listen to the cymbal decay. When the drummer hits a crash cymbal, does it sound clean and even, or does it get a bit glitchy and sound almost computerized? Any suspect distortion is probably an indication of poor quality. 

    2. Can you clearly hear the separation between the guitar, bass, and vocals? Or is it all a bit muddled, like you’re looking through frosted glass? 

    Joe Puglisi
    Joe Puglisi
    Joe Puglisi is an NYU grad and the Managing Editor of Baeblemusic. You can email him at joep (at) baeblemusic.com if you want him to listen to your music, go to your show, or write nice things about you. In his spare time he enjoys haunting New York's rock clubs, a nice whiskey, and tweeting. Baeblemusic brings to its growing audience exclusive video and editorial programming focused on highlighting the most interesting music acts of today across the country. Their voice is positive -- they are fans -- here to bring a curated and exclusive selection of artists and editorial to their devoted audience.

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    • http://profile.typepad.com/6p0120a5b4c045970b twitter.com/Spartz

      I was wondering…
       
      What do you base this on exactly: “when your brain has to work too hard to fill in the blanks, it gets tired of listening.”
       
      I’m really interested in digital audio and would love to see the research which backs up this claim.

      • http://www.facebook.com/profile.php?id=100003406351217 Kalpesh

        I had no idea how to approach this bfoere-now I’m locked and loaded.

    • http://profile.typepad.com/mylifescoop Lifescoopreader

      “Actually, you’ve hit on probably the most interesting facet of psychoacoustics in the article, and the one that’s not quite settled. The effects of removing frequencies and “tricking” the brain are still under debate. If you’re interested in further reading, look up some studies done on missing fundamentals (the removal of a base frequency to fool the mind into thinking it’s there) in digital audio. I’m afraid I don’t have a specific source to cite on this. Thanks for reading!” – Joe Puglisi