[Joe Bloggs]

Quote:

Originally posted by TonyTripleA Ross, a nice bit of double blind testing with a twist, or is that double, double blind. Anyway congrats. It reinforces my own unscientific opinion that I cannot differentiat WAV from AAC at 320 on the Ipod with etymotic 4P phones. I don't claim to be an audiopile though. I'm not so sure I would call your sample size insufficient. Many a meaningful experiment in biology was designed to have sample sizes of around 30. The minimum sample size can be calculated but at first glance I would suggest (as an old ex-scientist) that your results indicate no significant difference with a high degree of certainty.

I believe by sample size he was referring to the number of people tested in the experiment.

 

[Luke]

Here's a snip from an old article related to this topic that some may find interesting. Keep in mind it's just a bit dated (7/01):

Which brings me to an issue regarding media: MP3s. Sure, my computer’s hard drive is loaded with time-shifted copies of music that I have previously purchased (ahem), but I never regarded them as anything approaching hi-fi, especially when listening via my Rio player or my laptop’s speakers. I mentioned something to that effect to Tyl Hertzens of HeadRoom, and he replied that I shouldn’t jump to such hasty conclusions. He told me that MP3 decoding is a completely different process than WAV (CD-ROM) or Redbook (CD music) decoding, which results in a more "organic" sound.

He went on to say that MP3s with sampling rates in the 300+ kbps range can sound *better* than CD.

Tyl is onto something. I am not about to say that MP3s played back through a hi-fi rig compares with CD, but I agree that MP3’s strengths and weaknesses mesh well with headphone playback. For example, with the high resolution capabilities of the TAH and Sennheiser or Grado, I heard further into many recordings than I could with my home rig. I perceived the decay of plucked notes on an acoustic guitar and the startling snap of snare drum shots, and could even distinguish among the drums used. And there was no harshness whatsoever. (I typically listen at a sampling rate of 128 kbps, which is a pretty good comprise between compression and not). In terms of its smoothness, it made me think I was listening to quality tube gear. That is a tough feat to pull off: "smooth detail." Furthermore, I was starting to eat my words regarding soundstaging. MP3 is a reflection of CD in the sense that some recordings are imbued with much more ambiance and dimensionality than others. On some MP3s, I could actually hear beyond the soundstage and into the ambiance of the recording venue, which, as I said, is my hi-fi Holy Grail. Admittedly, the soundstage was still not in the shape or position that I prefer, and yet I was amazed that I was getting that kind of sound from an MP3. Other hi-fi attributes were also present on MP3 via the HeadRoom: dynamic punch when called for, and a tight bass perhaps in the 30-hz range from a particular synth-based recording. I have no basis to compare what TAH is doing for MP3s relative to other headphone amps, but I can tell you that MP3s lost much of their magic without the amp. I never thought I would use "MP3" and "magic" in the same sentence…

Much of that smoothness must be attributable to the nature of MP3, because CDs played back on the TAH sounded much more "digital." This fidelity to the source material is a tough trick to pull off. It seems to me that the TAH is relatively neutral and balanced, but with a tad of smoothness thrown in, meaning that harsh CDs still sounded harsh yet somewhat smoothed. I mean smoothness in a good way: that which comes from a top-notch solid-state amp, detailed yet inoffensive. Or was it perhaps the smoothness that comes from a top-notch tube amp, warm-sounding with high-resolution? I guess the answers depend on one’s perspective.

<end snip>

http://www.stereotimes.com/acc071301.shtm

 

[pbirkett]

Good post Ross, and one which I feel not very surprising, yet try convincing hardcore audiophiles, its definitely an exercise in futility. I blind tested some audiophiles once, and not one of them got it right both times (a very limited test, but still somewhat valid). Yet even after that, there was one or two who still felt the difference was obvious, even though they managed to get it wrong

 

[jboehle]

Great post!

Does anyone have any links or thoughts describing the technical and/or subjective differences between MP3 (LAME, others)/iTunes AAC/other compressed music formats.

-Jason

 

[blessingx]

Hydrogenaudio is a good jumping off spot. Check the general and technical forums.

 

[Zoomie]

I recently faced the same dilemma. I bought a 20G iPod with the intention of using WAV only. During the first week, it seemed my iPod was having trouble with the large file sizes that go along with WAV, short battery life notwithstanding. In an attempt to achieve greater stability and longer battery life, I thought I would give AAC a shot.

I ripped with EAC and encoded everything at 224 in iTunes. The results surprised me quite a bit. I had sworn up and down that I would never listen to lossy formats, but I am a changed man. I didn't design an experiment - like Ross - but indeed I ended up shedding my preconceived idea that compressed files were completely unacceptable and compromising. Boy howdy, I am sure glad I did. My quality of life has substantially improved by having thousands of songs at my fingertips, almost anywhere. I still prefer CDs in my home rig, but I would suspect that is the difference in sources rather than media.

Incidentally, I used the iPod dock lineout and a Zu Pivot IC to hear the iPod through my B&W 601s. Again, there was a difference, but very subtle. It's too bad my transport doesn't support AAC, I would love to compare sources.

Here's to coming clean

 

[iamdone]

I just recently came to the other conclusion. I had LAME 256k mp3s with ety er-4s and hd650/zu. Even with a PPA amp, some of my 80's cds just didn't sound the way I remembered them even though I had much better equipment. I just figured they weren't mastered that great. I was very reluctant to switch to WAV because of the time to re-encode and space issues.

Well I finally made the plung and don't regret it at all. My 80's collection now sounds better than ever. Everything seems more satisfying. It's more of a feeling than the actaully sound quality but you can hear deeper bass and there's a sparkle in the highs that are missing with mp3s. It's not a huge difference for portable devices but I also plan to use my files over a home network as well.

p.s. If you are going to use lossless files on the ipod, I suggest you use AIFF files even on the pc. iTunes uses hidden tagging with AIFF files that it can retrieve even when moving your files around. WAV files contain no tagging and are only stored in the iTunes database. The tagging info will be lost if you ever move the file.

 

[br--]

I'm surprised that many of you can't tell the difference between compressed and uncompressed music.

I was just comparing WAV, 320kbps AAC, and 320kbps MP3 on my speaker system (from my computer, not the iPod). The difference is huge. The WAVs seem to have a lot more life to them, and the sound is much bigger. It is hard to explain, but when listening to AAC/MP3 it sounds like the pleasant ambient noise that makes the recording sound exciting and lively is entirely removed.

edit: And if anyone is interested, for the iPod I use 256kbps AAC. I find it is the best compromise between sound quality and file size.

 

[Dylan]

The point is that several of us would have sworn we heard significant differences just as you do. But after a blind test to remove preconceived notions, we discovered that the differences were much smaller then we expected or non-existant at all.

Why not try a test like this yourself? What's to lose? It's real easy to conduct on a DAP by setting up a playlist of two songs, turning on "repeat all" and then flipping around fash enough that you don't know which song you end up on. Then listen and see how accurate you are.

 

[iamdone]

I just find the lossless files much more satisfying. When I do a direct test it hard to tell the difference but when you listen to a whole album, you're brain knows it sounds and feels better. I think there's more to the music than what you can just pick out in a test. I read an article regarding how the sounds beyond our hearing spectrum still effects what we actually hear. I think this would make an even bigger difference with speakers because of the vibrations on the body that we feel but can't hear.

The other advantage to having lossless files on your pc is you can always convert them to the latest formats without re-ripping them. So if the ipod supports FLAC or AIFC in the future, I get the same quality but free up a lot of hd space.

 

[Ross]

Quote:

When I do a direct test it hard to tell the difference but when you listen to a whole album, you're brain knows it sounds and feels better. I think there's more to the music than what you can just pick out in a test.

I think this is absolutely correct, and that this is the critical issue. This is why I suggested earlier that the kind of A/B comparison that most people call "double blind testing" is not really appropriate for hi fi and that a better experiment would involve monitoring people's listening habits over very long periods of time to determine unconscious preferences for one format over another. But this type of experiment would be far too difficult, expensive and time-consuming for most purposes, and certainly for most reviewing purposes.

Having said that, I do think a lot of what we regard as "satisfying" is determined by our perception. As I indicated in my first post, I felt instinctively that the uncompressed files were more musically satisfying than the MP3 files, until I realised that I had mistakenly reversed them. I think this says more about bias and perception than it does about audio fidelity.

Before I did the experiment, whenever I listened to a file that I knew had been recorded in MP3, there was something preventing me from enjoying it, and I often attributed it to "audible" artifacts such as lack of ambience or texture, lack of tonal colour etc. After the experiment, when I realised I had been wrong about this, I have been able to enjoy listening to MP3s without any of these problems, including instrumental tracks which would highlight these issues if they existed. This morning I listened to a complete Schubert string quartet on the way to work and found it extremely satisfying.

I also think it is interesting that the sort of things that people claim about MP3 vs WAV are exactly the sort of thing that people have been saying (and continue to say) about CD vs LP, and I'm still convinced that LP is a more musically satisfying medium than CD.

 

[Dylan]

Quote:

Originally posted by iamdone When I do a direct test it hard to tell the difference but when you listen to a whole album, you're brain knows it sounds and feels better.

I agree that there is some merit to this. Ross stated very well the difficulty in doing a valid abx test for audio that must encompass a long period of time to accurately reproduce the normal listening conditions.

But here are some of the quotes from just this thread:

The difference is painfully obvious...

...you can hear deeper bass and there's a sparkle in the highs that are missing with mp3s

The difference is huge.


These are not the sort of comments you make about a vague difference in your level of satisfaction. If you can hear a difference to the degree as in the above quotes then you should be able to pick that out easily.

What Ross, myself, and others are saying is that we used to believe the differences were of the magnitude similar to the above comments. But when we removed our bias we learned that the difference was much more subtle then we had believed.

The point is not what equipment we used or whether our test was valid for long term satisfaction. The point is that we learned our perception is influenced by our bias. Ross and I certainly aren't alone in experiencing this human trait.

Try it yourself. I gave a simple test above that can be performed with a DAP. The only thing you have to lose is that you might have to change some of your existing notions to match a newly proven reality. Is that so bad? For Ross and myself, this new knowledge has lead to greater enjoyment of our music. Isn't that the goal?

 

[Joe Bloggs]

Quote:

When I do a direct test it hard to tell the difference but when you listen to a whole album, you're brain knows it sounds and feels better. I think there's more to the music than what you can just pick out in a test.

But a test is the only reliable way of detecting differences. With training some people are able to pick out 320kbps mp3s from uncompressed wav files in a DBT every time. Isn't that much better than some vague impression that wav 'should' sound better because you already know it's a wav? These people would readily tell you that not being able to carry out a DBT lowers their ability to detect real differences between 2 sources because expectation bias creates differences out of thin air.

 

[iamdone]

Basically just use what works for you. If lossy files work, great. I tried them for a while but am now convinced lossless files sound better and will continue to use them.

As, I said regardless of how they sound, having a lossless file while allow you to encode to whatever formats the future holds. Transcoding will always result in a further loss of sound quality.

 

[DeadTrying]

For what it's worth i'm of the opinion that you should store two copies of all your music on your PC.

The first copy is a lossless encoding in something like the flac format. This essentially compressed wavs to roughly 2/3 their size but the sound is a digitally perfect copy of the original

The second copy is a portable copy encoded in was, ogg or whatever tickles your fancy (or whatever your player supports). For this purpose I usually encode at 160-192kb/sec in mp3 format. I know that as time goes by better compression algorithms will be released (E.g. AAC) and when they become more widely supported on portable players I'm going to want to convert everything to that format.

Having the lossless 'backups' mean that this can be done quickly and easily, especially if the format supports ID tags. You can also listen to some of these formats in Winamp with the right plug-in just as you can do with a normal MP3s so when you're in audiophile mood you could just listen to these instead.