I probably shouldn't say this  because I don't think anyone who reads this will ever take me seriously when (if) I comment anything on this forum...but : I ripped a track from a CD with a very high quality recording of music with a lot of dynamics, acoustic instruments and vocal. Then I converted the WAW file into 320 kbps and 128 kbps MP3 files.
I imported the files into sonar and used solo exclusive to toggle between the WAW and MP3 files. I tried to loop short and long passages, but I could not hear any difference!
I used a frequensyanalysator and I could see a drop in the high freqs (above 16 Khz) in the 128kbps file, but I couldn't hear it.
So the question is: Is it just a matter of listening training or are the soundquality of MP3 better than the people claim ?
(I hear people say that they can't listen to MP3 because  of the bad quality.....??)
 
My soundcard is an ECHO audiofire 4 going trough a Yamaha MG 166CX mixer and into ADAM A5 speakers.

Waw file? I'm assuming you meant .wav file?

As w/ any lossy format, there is, well, loss.  A lot depends upon the music, the listener and the playback system.  And what you are used to.  Ear buds are hardly a good transducing system, and a car is full of noise.  I wouldn't expect to hear a lot of difference.  But the better the listening equipment and enviornment, the more likely it is to be an issue.

Finally, ears.  Most people don't listen.  Musicians do.  and engineers, that is their job.  They develop their ears to hear the differences.  They are not listening to music so much as the sound of the music.  So don't kick yourself if you can't tell.  Even on a good system there might not be too much difference since 320 kps doesn't do too much masking. 

Do this, convert a song you know well to the lowest rate you can and then listen to it.  See if you can learn to hear what to look for.

@

yes.  I can hear a difference between wave files and 128k mp3's.  I can't hear a difference between 320k mp3's and wave files, tho and anywhere in between 128k and 320k depends.  some music I can, some I can't.

it will also depend on the genre of music you're listening to as well.  if all you're listening to is hard rock or death metal or something that's slammed to a brick then you might not hear any differences. 

I too can defo hear the difference in 128 and a wav, its very apparent in the highs, they come across wishy washy and grainy. 192, 256,320, honestly I dont really know, certainly not the latter two.

Cian

You're not supposed to hear any difference. That's the whole idea behind perceptual encoding: you're only removing stuff you can't hear anyway.

There's a plugin out now that does MP3 encoding on the fly, so you can hear what your mix will sound like after encoding. It has a feature that allows you to hear just the stuff that's being removed. Many reviewers have noted how scary that is, to hear what's going to be missing, and it reinforces their belief that MP3s are horribly inadequate. But the truth is you weren't going to hear those things in uncompressed waves, either.

I am, of course, talking about higher bitrates, 192 kb/s and up. At 128, you can usually hear the degradation clearly, especially in an A/B audition. But at 256, it's very difficult to hear the loss, and even then only on high-pitched sounds such as triangles. The music you listen to on the radio was probably delivered electronically to the broadcaster as compressed data which (though not MP3) is equivalent to about 256 kilobits per second.

Far more relevant is the quality of the playback device. Sadly, the majority of portable MP3 players have dreadful DACs in them that are prone to aliasing. Even high bitrates can't save those abominations.  

this has been beat to death...

most pros, which we have to look to for guidance, can easily hear the difference in their professional studios, which most of us don't have anything even close to matching the performance ability of those types of studios.

just because you cannot hear the difference, doesn't mean it isn't there.

would you rather ignore the sage of advice of professionals who have already done these tests for themselves, and told everyone else what they found out?

or just trudge ahead and damn the status quo?

For a start, it is very dependant on the music content. Of you have a lot of cymbals and high frequency stuff going on, it's going to be very audible. If you just have a simple track with a bass and deep mellow singing, things are getting more difficult. In my experience. The lower the mp3 bitrate, the lower the perceived frequency attacking (to my ears). Why do you think they use variable bit rate encoding? It's based on the fact that more complex material needs a higher bitrate to adequately 'trick' the human ear and simple stuff you can get away with a lower bitrate. I typically think a variable bitrate encoding of say 192-320 is more than adequate for everyday listening. It'll only go down to 192 if it needs to and stay at 320 if it needs to. So as long as the encoder reliably gets this, we are good!

128, I believe I can hear all the time if I listen. Some songs it stands right out at you and punches you in the ears. Other songs you don't really notice, till you listen, and then you can't listen to it anymore once you realised as you then hear it like daylight.

320, sometimes. I have done a direct A/B of some of my music before and I could hear a VERY subtle difference in the high frequency content. The .wav just seemed that teeny little bit clearer and sharper in the very top of the highs. But if you gave me a 10 minute break between listening to the two samples, I highly doubt I would be able to hear the difference. Thus my conclusion is 320 is perfectly adequate because I don't think I could pick it out in real world examples (ie direct A/B ing two versions is NOT real world - that's not how we listen to music).

And although I have never tested for or experienced it, there should be difference in different .mp3 encoders. The new encoders should be much better at 128 than the original ones at 128 when .mp3 first came out.

After years of working with heavy machinery and playing in local bands (and firing 106mm mortars in the army) I doubt if I could hear the difference because of my hearing loss. High frequencies? What are those? But I still encode my songs at a high bitrate for others who may listen to them. I only use a lower bitrate if faced with size restrictions.

You betcha. The difference between an MP3 and raw wave (CD) is dramatic. But you require some decent equipment (and ears) to hear it. Most iPods and MP3 players, and low to mid range monitors do not have the resolution to hear the difference. But, compare them on a quality hi-fi and you will be stunned at how bad they sound. The losses are dramatic. FLAC and other lossless formats do a much better job, but nothing compares to a raw wave.