The Listening Test from a few weeks back was interesting.
I had a few votes come in by email, and adding those to the ones made publicly in the comments, we get this result:
File 1:
- 63% said it was the 75% WMA
- 25% said it was the FLAC
- 12% don’t knows
63% of respondents were correct: File 1 was indeed the 75% WMA.
File 2:
- 63% said it was the 10% WMA
- 25% said it was the 75% WMA
- 12% don’t knows
63% of respondents were indeed correct. File 2 was the 10% WMA.
File 3:
- 88% said it was the FLAC
- 12% said it was the 10% WMA
Most people got this one right: File 3 was indeed the FLAC.
So it seems as if most people really can tell the difference between uncompressed and compressed music formats -but it’s a relatively narrow call when it comes to telling the difference between gentle compression (75% WMA) and drastic compression (10% WMA). Most people got it right even so, but the margin was quite a bit narrower.
I asked the question because (I am somewhat sad to find) I couldn’t tell the difference between the FLAC and the 75% WMA, in good listening conditions (Bose speakers, etc), despite the one file being just 15% the size of the other. It would seem my ears are not as good as I thought (it expect it comes with age!) 
Happily, I could spot the 10% WMA a mile off, the compression artifacts making me grit my teeth at one point.
I then tried the experiment on the train, listening via ear-buds and playing from a Samsung Galaxy SII phone: and all three files sounded exactly the same, perhaps unsurprisingly (everything sounds crap on a train!)
The point being that, as I approach 50, it’s perhaps unnecessary for me to upgrade my RAID array from a mere 8TB to 12TB (which will cost a bomb, with 3TB hard disks still costing around the AU$300 mark). I could compress all my music files instead, saving as much file capacity as I was planning on adding, and I’d never tell the difference. (Except that, of course, I would know, intellectually, that frequencies were missing, and that would annoy me no end. So I’m sticking to FLACs for now, even though they are unnecessary for my particular pair of ears!
Music is music and a performance will involve the listener based on its musicality, not the quality of the audio transmission.
That said: highly compressed formats do also make my teeth grate, but an LP player which isn’t playing at constant speed due to a worn belt does the same.
Certain instruments or sorts of music are more susceptible to compression artifacts than others: I’m an organist and as such listen to lots of organ music. The organ has a complex aural waveform, and a wide dynamic and frequency range. Once you’ve heard organ music highly lossily compressed you learn to easily identify the artifacts, which in turn increases one’s demand of higher frequency recordings.
I find that listening through headphones increases my awareness of compression artifacts: probably also partly due to most compression being done across both stereo channels at the same time, causing the compressed sound to “move around” somewhat compared to the original.
For listening in a car, train, aeroplane or other noisy environment it may actually be better to also normalise the volume levels when compressing. It’s almost impossible to listen to organ music in such an environment unfortunately. Harpsichord with its constant volume is best
Don’t sell your ears short. In general, age-related hearing changes are losses at the high end, along with any particular frequencies that have abused your inner ear. Discrimination tends to be learned, as does familiarity with particular systems. Bose speakers are supposedly designed with a bias towards classical music, so whatever the details of your system, it probably is a fair test you’ve made. However, if you change speakers, even to cheaper ones, it may surprise you. I have speakers from 5 different decades, and am still amazed at what can come out of “multimedia” computer speakers. I’ve had Bose speakers, and they always sounded kind of wrong or muddy to me, which I just ascribed to learning or acclimation or design bias, without much thought. But you made me curious, and looking for frequency response I found http://www.intellexual.net/bose.html
It may not be your ears so much as a demonstration that compression is nearly good enough. There is also so much of a subjective component that it may be hard to truly be scientific about it – one might hear a difference without consciously discriminating it.
I can definitely hear the difference between what comes out of my car speakers from the compressed satellite feed, FM radio, and cd’s, for the same song (FM is often the best, though stations vary). But when I hear something on satellite that I can’t download or buy, the content overrules everything, including my dislike of paying for satellite. I’ve only just started putting mp3′s that I’ve ripped from albums on my android, so that comparison hasn’t happened yet.