I opened up iTunes yesterday and navigated to the iTunes Plus page. I was offered with the opportunity to upgrade my 21 EMI tracks to the new format for $6.30 ($0.30 a piece). I accepted the offer. I'd like all the music companies to let their music use this format; and this is how we consumers vote, with money. Not that Apple's DRM has hurt me. About once a year, my iPod forgets it's authorized to play my tracks, requiring a sync; but otherwise it's been transparent. What I like is the knowledge that my music is now truly my music, and the quality.
I know some people believe an ordinary person can't tell 128 kbps from 256 kbps AAC files, and this may be literally true when comparing 10 second clips in one and 10 seconds in another. The difference is in the long term.
Backing up. In one of my previous incarnations, I helped write the ill fated OS X client for MusicMatch. Ill fated because Apple came out with iTunes and it's hard to compete with free.
People at MusicMatch were used as convenient guinea pigs to determine just how much you could compress various styles of music before you started to hear the compression; the more compression the more MusicMatch could save on bandwidth costs. Too much compression, and people would hate it. The goal was to deliver good sound, but not wastefully good sound. We'd put on big noise isolating head phones and listen to several clips at various compression levels, plus an uncompressed version, straining to hear the difference. Over and over for an hour. I became reasonably good at catching the differences, picking out the instruments especially susceptible to distortion, those that rattled, scratched or were high pitched went first; the fine details lost; things like bass guitars not so much.
And sometimes I couldn't tell the difference. But one thing I can tell you about overly compressed music, even that which I couldn't discern from the original: it made me sick. Not throwing up in the waste basket sick, but mildly nauseated or at least a general feeling of non-wellness. At the time, I thought it was just from having to listen to the same Backstreet Boys riff too many times, but I have a new theory.
Music is compressible because the human mind can be fooled. The AAC and MP3 codecs use psychoacoustic tricks which make the mind think it's hearing what it isn't. The actual sound waves don't look much, if anything, like the original; the details are faux. For me, this trickery disorients and tires my brain, and the more compressed the more intense the feeling. The less compression, the less trickery, and the more wholesome the music. Not that 128 kbps AAC is as bad as 96 kbps MP3, I'm just saying I can barely feel the unnaturalness of it. Similarly, I hate listening to stereo music being manipulated by the Dolby Pro Logic filter through my SphereX surround speakers, a few seconds of that and I'll be diving for the remotes 2.1 button and its refreshing clean sound.
I'm listening to some Norah Jones in iTunes Plus format now. Her piano sounds rich and beautiful; I love the sound of a grand piano. I feel good. The music is making me feel quite mellow. I can't tell that the harmonics of the acoustic guitar in my left ear are more realistic or the tambourine being slapped in my right ear are less distorted, but my sense of well being does. So, anyway, I paid my $6.30.
[Update: I suppose I should point out that I'm not claiming any expertise in audio compression or the psychology of sound perception. I'm an application programmer. No sensible person would hire me to write an audio codec.]