The AAC - MP3 - WAV Challenge!

[8O]

I'll come clean as being "Test subject A" - i.e. the one with cloth ears. As well as more results, I look forward to reading people's excuses why they didn't get it right, why they think the test is flawed, etc...

[timwright]

I'm test subject B.

[anamexis]

twisted-space just nailed the MGMT and Sinatra tests - meaning, he ranked them WAV, AAC,MP3. Interestingly, though, he ranked Beethoven as MP3,WAV,AAC.
But he's still the only person to even come close.
The test goes on. Put your money where your mouth is, "AAC is significantly better than MP3" people

[twisted-space]

The Beethoven files were the last set I listened to. My ears must have been getting tired
That or the MGMT stuff just destroyed my hearing!
Cool experiment, I'm looking forward to seeing more results.

[8O]

When a lot more results are in, I'd really be interested in discussing with golden ear kids like twisted-space about exactly where the differences were perceived and then, when one knows exactly what to listen for, whether mud ear kids like me can then hear the differences, or whether we're really deaf.

But let's keep that for later...

[locojohn]

When a lot more results are in, I'd really be interested in discussing with golden ear kids like twisted-space about exactly where the differences were perceived and then, when one knows exactly what to listen for, whether mud ear kids like me can then hear the differences, or whether we're really deaf.

But let's keep that for later...

How cannot you guys understand -- it's not a question of going into extremes and challenging those being golden-eared or deaf! MP3 is an extremely advanced algorithm that uses a few theories:

1) that a human ear, in general, cannot perceive any sound below what is considered to be digital silence (-90 dB)
2) that a human can hear the sounds in the range between 20Hz till 20Khz at best! Which, in practice, is almost never the case.
3) that a human ear is most sensitive between 2Khz and 5Khz and therefore it perceives sound in this range better, meaning that it is possible that some loud sounds in this range can mask/hide quieter sounds in less sensitive areas.

The science of how humans perceive sound is called psychoacoustics, and it has discovered a number of useful auditory effects. For example, the Haas effect, which states that two identical sounds arriving within 30-40ms of each other from different directions will be perceived as a single sound coming from the direction of the first.

MP3, like many other lossy audio compression schemes, relies heavily on these kinds of psychoacoustic effects to work its magic. In particular, it exploits the phenomenon of frequency masking. In short, in a single track when one sound at 100 Hz is louder than another sound at 110 Hz, only the former will be heard in the mix.

We really don't have to compare the lengths (or widths) of our... The point is that the latest algorithms employed in lame 3.98 in its high quality settings will make even a person with "golden ears" barely notice a difference between the PCM and MP3 versions of the music. It's psychoacoustic science and it works. And if they do notice a difference, the 90% chance is they simply want to hear it.



Andrejs

[twisted-space]

When a lot more results are in, I'd really be interested in discussing with golden ear kids like twisted-space about exactly where the differences were perceived and then, when one knows exactly what to listen for, whether mud ear kids like me can then hear the differences, or whether we're really deaf.

But let's keep that for later...

I'm a bit old to be a "golden ear kid". It'll be interesting to discuss this when we have a few more results in though.

[8O]

You misunderstand me, Locojohn, I understand how the compression techniques work and I agree with you. I've done blind tests myself between 192Kbps AAC and WAV and even then the difference was very slight. I am perfectly happy to accept that WAV = AAC = MP3 in this test. I'm just interested learn something new from people who *can* hear a difference... Especially as this is a blind test, so hopefully any "wanting to hear a difference" effects will be cancelled out...

[twisted-space]

The point is that the latest algorithms employed in lame 3.98 in its high quality settings will make even a person with "golden ears" barely notice a difference between the PCM and MP3 versions of the music. It's psychoacoustic science and it works. And if they do notice a difference, the 90% chance is they simply want to hear it.



Andrejs

How could I want to hear a difference when I didn't know which file was which. Surely that's the whole idea behind a "blind" test.
I would like to discuss this when more results are in.

[locojohn]

How could I want to hear a difference when I didn't know which file was which. Surely that's the whole idea behind a "blind" test. I would like to discuss this when more results are in.

I was not referring to you personally, or anyone else in particular. I only think that tests like this will again show that we all perceive sound differently, in a non-linear way typical for each particular person individually, and that neither is truth: "AAC is different than MP3", "MP3 is the same as AAC".

Andrejs

[twisted-space]

I was not referring to you personally, or anyone else in particular.

Understood, I was referring to this comment:

if they do notice a difference, the 90% chance is they simply want to hear it

I wanted to point out that in the context of this test, that is simply untrue.

Also I can't agree with:

neither is truth: "AAC is different than MP3", "MP3 is the same as AAC".

AAC is different to MP3 which is different to WAV, that is unquestionable.
The question is can I (or you, or anyone else) perceive the difference?

Just out of interest, have you tried the test locojohn? Can you hear a difference?

[locojohn]

The question is can I (or you, or anyone else) perceive the difference?

Somehow, this is what I don't find too interesting. Everybody will want to find the difference, though, no question about that. Hehe.

Just out of interest, have you tried the test locojohn? Can you hear a difference?

No, I haven't tried this particular test, but I have been doing tests like this myself for weeks when I got interested in this subject. I have a few special reference CD's with rather complex and very well recorded choir/orchestral music which I used to compare when checking loudspeakers and mp3s vs wav's. This time I'd like to skip the test, if you let me please.

Andrejs

[8O]

I have a few special reference CD's with rather complex and very well recorded choir/orchestral music which I used to compare when checking loudspeakers and mp3s vs wav's.

Hey, this is great - you can give a anamexis a full quality version, he can convert them and you can blind test yourself!

[twisted-space]

This time I'd like to skip the test, if you let me please.

Of course, I just thought you might find the results interesting, especially as you seem to have a strongly held opinion on the matter.

[anamexis]

Besides, I need more data, do it for the team