Inside the MP3 Codec - Masking Effects
I wondered about this questions while flying home, listening to my AAC (MP4) encoded music on my iPod. These are old songs and tunes, yet I seem to hear more than I used to. Certainly neither my ears or my brain are improving; entropy rules. Probably it's simply using better headphones, and and perhaps the experience of listening with more care to more music. My iPod has brought more music to my middle-aged gray days than all the toys of my youth.
And yet ...
Lossy compressed music is fundamentally quite different from non-compressed music. It sounds reasonably similar to the original music because of our brain can't fully detect all the missing elments, and because in some ways the brain "recreates" what isn't heard by the ear. This lossy compression effect is usually considered a necessary evil; an unsatisactory compromise with the storage limitations of current technologies.
But one could hypothesize that the overall experience might in some way be "superior". With the 'unheard sounds' removed, can the brain better focus on the fundamental sounds? Could the process of 'filling the gaps' be in some way 'pleasant' for the brain, a mild excercise that is stimulating and agreeable?
It's easy to imagine all kinds of interesting experiments with different compression levels, different music, functional neurocognitive imaging, etc. I hope to read about these soon ...
It would be funny if it turned out that part of the appeal of the iPod is that people like lossless encoded music better than the 'real' thing.