Apple's iTunes store—in partnership with EMI —is now hawking DRM-free music at twice the bit rate of its standard fare (256Kb/s vs. 128Kb/s) and charging a $0.30-per-track premium for it. We’re all for DRM-free music, but 256Kb/s still seems like a pretty low bit rate—especially when you’re using a lossy codec.
So we decided to test a random sample of our colleagues to see if they could detect any audible difference between a song ripped from a CD and encoded in Apple’s lossy AAC format at 128K/s, and the same song ripped and encoded in lossy AAC at 256Kb/s.
Our 10 test subjects range in age from 23 to 56. Seven of the 10 are male. Eight are editors by trade; two art directors. Four participants have musical backgrounds (defined as having played an instrument and/or sung in a band). We asked each participant to provide us with a CD containing a track they considered themselves to be intimately familiar with. We used iTunes to rip the tracks and copied them to a fifth-generation 30GB iPod . We were hoping participants would choose a diverse collection of music, and they did: Classical, jazz, electronica, alternative, straight-ahead rock, and pop were all represented; in fact country was the only style not in the mix. (See the chart at the end of the story for details.)
We hypothesized that no one would be able to discern the difference using the inexpensive earbuds (MSRP: $29) that Apple provides with its product, so we also acquired a set of high-end Shure SE420 earphones (MSRP: $400). We were confident that the better phones would make the task much easier, since they would reveal more flaws in the songs encoded at lower bit rates.
We asked each participant to listen with the Apple buds first and to choose between Track A, Track B, or to express no preference. We then tested using the SE420’s and asked the participant to choose between Track C, Track D, or to express no preference. The tests were administered double-blind, meaning that neither the test subject nor the person conducting the test knew which tracks were encoded at which bit rates.
The biggest surprise of the test actually disproved our hypothesis: Eight of the 10 participants expressed a preference for the higher-bit rate songs while listening with the Apple buds, compared to only six who picked the higher-quality track while listening to the Shure’s. Several of the test subjects went so far as to tell they felt more confident expressing a preference while listening to the Apple buds. We theorize that the Apple buds were less capable of reproducing high frequencies and that this weakness amplified the listeners' perception of aliasing in the compressed audio signal. But that’s just a theory.
Age also factored differently than we expected. Our hearing tends to deteriorate as we get older, but all three of our subjects who are over 40 years old (and the oldest listener in the next-oldest bracket) correctly identified the higher bit-rate tracks using both the Apple and the Shure earphones. Three of the four subjects aged between 31 and 40 correctly identified the higher bit-rate tracks with the Apple earbuds, but only two were successful with the Shures. Two of three under-30 subjects picked the higher-quality tracks with the Apples, but only one of them made the right choice with the Shures. All four musicians picked the higher-quality track while listening to the Apples, and three of the four were correct with the Shures.
Despite being less able to detect the bit rate of the songs while listening to the Shure SE420 earphones, eight of 10 subjects expressed a preference for them over the Apple buds. Several people commented on the Shure’s ability to block extraneous noise. While listening to the SE420s, one person remarked “Wow, I’d forgotten that wood-block sound was even in this song.” Another said “The difference between the Shure earphones and the Apple earbuds was more significant than the difference between the song encoded at 128Kb/s and the one recorded at 256Kb/s.” One of the two people who expressed a preference for Apple’s product told us “It seemed like I got better kick from the bass.”
To our subjects’ ears, there wasn’t a tremendous distinction between the tracks encoded at 128Kb/s and those encoded at 256Kb/s. None of them were absolutely sure about their choices with either set of earphones, even after an average of five back-to-back A/B listening tests. That tells us the value in the Apple’s and EMI’s more expensive tracks lies solely in the fact that they’re free of DRM restriction s .
And as much as we dislike DRM, we just don't think DRM-free tracks alone are worth paying an extra 30 cents a track for. We'd be more excited if Apple increased the bit rate even further, or--even better--if they used a lossless format.
In the end, Apple's move doesn't change our opinion that the best way to acquire digital music remains buying the CD: You can rip and encode it at any bit rate you want, you can transfer it to any device you want, you know you won't have any DRM issues to worry about, and you won't have to pay anything extra for it.
As for buying high-end earphones, eight of our 10 test subjects enjoyed listening to the Shure SE420’s more than they did Apple’s stock buds--an interesting finding since fewer listeners correctly identified the higher bit rate tracks with the Shures than did the Apples. We suspect that the performance of the Shures masked the flaws in the tracks encoded at lower bit rates.
Your audio system is only as strong as its weakest link, and if you're listening to cheap earphones, you're missing out on what your MP3 player is capable of delivering. The SE420's fit tight inside your ear canal, so they isolate your ears from extraneous noise. Many of our listeners found that they could turn the player's volume down significantly because the earphones weren't competing with environmental racket. That not only makes your listening experience more enjoyable, but it can also prevent hearing loss.
Despite what Apple charges for a set of its replacement buds, the earphones that come with 90 percent of the digital media players on the market are throw-away items--they're only in the box so you'll have something to listen to when you bring the player home. Do yourself a huge favor and dump 'em. Spending a few bucks more for something that sounds better, feels better, and will last longer just makes sense; after all, you only get one set of ears in life.
[Editor's note, 6/4/2007: We removed our comment about paying a premium for buying the entire album at the higher bit rate, since iTunes Plus albums, according to Apple's FAQ "are generally available at the same price as DRM-protected versions of the albums." If, on the other hand, you previously bought the entire album at the lower bit rate, an upgrade will cost, again according to Apple's FAQ, "30 percent of the album price."]
|ARTIST||ALBUM||TRACK||PICKED HIGH BIT RATE W/APPLES?||PICKED HIGH BIT RATE W/SHURES?|
|Nine Inch Nails||Year Zero||The Great Destroyer||Yes||No|
|Tea Leaf Green||Taught to be Proud||If it Wasn't for the Money||No||No|
|Guns & Roses||Use Your Illusion II||Civil War||Yes||Yes|
|Husker Du||New Day Rising||Celebrated Summer||Yes||No|
|Massive Attack||100th Window||Future Proof||Yes||No|
|Stevie Wonder||Original Musiquarium I Vol. II||Sir Duke||No||Yes|
|Mingus Big Band||Gunslinging Birds||Jump Monk||Yes||Yes|
|Sunday's Best||Where Are You Now?||Truest You||Yes||Yes|
|Andres Segovia||Legendary Andres Segovia in an All-Bach Program||Chaconne (from Violin Partita No. 2)||Yes||Yes|
|ARTIST||WHY THE LISTENER CHOSE THIS TRACK|
|Nine Inch Nails||"It has the typical chord progression of a pop song, and then it goes into this crazy, techno solo. I thought the variety would help me identify the differences in the bit rate."|
Tea Leaf Green
"This is a CD that I listen to a lot; I'm very familiar with it."
Guns & Roses
"This song is meant to be played loud. Axl Rose's voice and the guitars should help me tell the difference."
||"I've been listening to a lot of Husker Du lately. Sometimes you rediscover a band and wonder why you haven't listened to them for so long."|
||"I know this song so well. I figured I'd be able to tell if I was hearing everything that should be there."|
"I thought I'd be able to hear the difference in the sound of the horn section at the beginning of the song. I think the track with the higher bit rate will sound brighter."
Mingus Big Band
"I'll be listening for dynamic range in the horns. I think I'll perceive differences in the sound of the piano solo and the upright bass."
"The drummer in this band is cymbal crazy. I think it will be hard to capture that sound accurately at a low bit rate."
"I've listened to this recording 40 billion times. I know every nuance in it."
"This may be the world's most fanatical band when it comes to recording. One of the things I'll be listening for are the chimes in the opening."