Can you tell MP3 bitrates apart?

by Cosmo Lee

Sometimes “not good” is not only good enough, it’s preferable. Jonathan Berger, a Stanford music professor, conducted tests in which students listened to the same music in different audio formats. Each year, students increasingly preferred the sound of MP3’s. (Story here and here.) He attributed this to familiarity. Older generations prefer the distortion (“warmth”) of vinyl; younger generations prefer the distortion (“sizzle”) of digital compression.

I won’t replicate Berger’s study protocol, as I have better things to do than to track down, say, the vinyl, cassette tape, and CD of the same album. But I have set up a related taste test.

Here are MP3’s of “Onward into Battle,” from Katatonia’s latest album. Using LAME encoding at highest quality settings, I ripped them from CD at constant bitrates of 320, 256, 192, and 128kbps. These are the most common MP3 bitrates today. 320 is the highest, 256 is what Amazon uses, and 192 and 128 are common in the lo-fi rips that permeate torrents and donwnload blogs.

Can you tell a difference among these?

Onward into Battle (320)
Onward into Battle (256)
Onward into Battle (192)
Onward into Battle (128)

This test is rough, for several reasons. First, there is considerable debate as to the merits of constant vs. variable bitrates. For the sake of simplicty and uniformity, I chose constant bitrates. Second, “Onward into Battle” is hardly an ideal song for an audio taste test. It’s dense, over-produced, and mastered too loudly, resulting in dynamic-less, over-compressed sound. Ideally, I would have used, say, an original pressing major label metal album from the early ’80s. But I don’t own many CD’s now, so I made do with something I felt was varied enough in content to yield varied results. (Lo-fi black metal, for example, sounds lo-fi regardless of bitrate.)

Finally, each person’s equipment and ears are different. Much of my stuff is in storage, so right now my setup is low-quality. On $13 headphones, these MP3’s basically sound the same. When I had studio-quality nearfield monitors, 192kbps MP3’s sounded so bad that my hairs would stand on end. Since most people listen to music now on low-quality iPod headphones, perhaps bitrates above 192 are moot. Wired has a good article on how technology (e.g., MP3’s and YouTube) has shifted from “best” to “good enough.” I grew up before over-compressed mastering and digital compression, so I won’t ever prefer that sound. But for many kids now, that’s all they know.