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georgehifi

Hearing test: 16/44 uncompressed, 320kpbs mp3, and 128kpbs mp3

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On 01/09/2018 at 9:54 AM, aussievintage said:

I got 6/12 (I did it twice) correct. Enough to indicate that I do have some preference for the best files. 

No that's not.     Statistically, you will get "50% right" if you guess randomly..... and so the score needs to be substantially above 50% to start showing that result.

 

Quote

btw.  3 times out of 12 I chose the worst 128k mp3 ! Or, in other words,   I chose the better files 9 out of 12 times. 

Indeed.  That's more like what (9/12) would be 'starting to show a preference' ... and also supports the typical result that well-made high-bitrate MP3 is audibly transparent.   :) 

Edited by davewantsmoore

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1 hour ago, davewantsmoore said:

No that's not.     Statistically, you will get "50% right" if you guess randomly..... and so the score needs to be substantially above 50% to start showing that result.

 

Are you sure?  There were three choices, so random choice gives you 33% doesn't it?

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7 minutes ago, aussievintage said:

Are you sure?  There were three choices, so random choice gives you 33% doesn't it?

Geez, I'm glad someone is paying attention (not me).

 

Sorry.   Yes.     (I often do trials with choice A and B, so I just get 50% stuck in my head).   Carry on  🤐

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I got 5 out of 6 using my pc sending through HDMI to my AVR, and plugging in Sennheiser HD 800 phones. (I failed on the Mozart piano concerto by choosing the 320kbps version.)

 

I found the 128kbs mp3 distinctly "mushier" in all cases except the last piece of music. Generally I found it quite hard to differentiate the 320kbps mp3 from the uncompressed version. The fact I got 5 correct answers may partly be due to a lucky guess in one or two cases [after I had eliminated from contention the 128kbps version]!

 

This exercise would be much more difficult if a modern codec such as AAC were used (instead of the now dated and relatively inefficient mp3 codec).

 

On 31/08/2018 at 7:41 PM, georgehifi said:

Sennhiser HD650's straight into the computer headphone socket got me 5 from 6, and I only just hear to 16khz.

I understand that the artefacts of mp3 encoding can affect frequencies all over the audible spectrum. (My own hearing no longer extends as high as 16kHz.)

 

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If you don't get at least 5/6 sell your gear or upgrade. I always find mp3 has lumpy bass and bad distortion. Tidal do 6 months mp3 for free if you want "normal" service it costs, do they know something? 

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13 minutes ago, deblur said:

If you don't get at least 5/6 sell your gear or upgrade. I always find mp3 has lumpy bass and bad distortion. Tidal do 6 months mp3 for free if you want "normal" service it costs, do they know something? 

Audio files compressed with the mp3 codec differ in the noticeability of the artefacts depending on a number of factors including:

  1. the bitrate (128kbps being much more susceptible to creating audible artefacts than 320kbps)
  2. the nature of the music (e.g. complex orchestral music can be harder to encode successfully than simply textured music)
  3. whether an uncompressed version of the same music is available for immediate comparison.

 

I think the audible differences (such as they are) are revealed with even modest hi-fi equipment. (Having said that, very high quality equipment may make it a little easier to hear differences in a 320kbps mp3.)

I suggest @deblur that if a person cannot hear artefacts in a 320kbps stereo mp3 played on a hi-fi system, then the most likely explanation is that their hearing is tolerant of, and oblivious to, the minor artefacts arising from the compression to 320kbps stereo mp3.

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9 hours ago, MLXXX said:

This exercise would be much more difficult if a modern codec such as AAC were used (instead of the now dated and relatively inefficient mp3 codec)

Most results show they are both equally as transparent, assuming encoded well..... just at different bitrates (like you say, lower for AAC)

 

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56 minutes ago, davewantsmoore said:

Most results show they are both equally as transparent, assuming encoded well..... just at different bitrates (like you say, lower for AAC)

 

I meant using the same bitrates as used in this test. I know from my own listening experience that 320kbps stereo AAC is indistiguishable from an uncompressed version except in occasional passages in the music and needs very careful immediate A B comparison for me to be able to hear any difference.

 

As for 128kbps stereo AAC, I find that a distinct improvement over 128kbps stereo mp3.

Edited by MLXXX

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8 hours ago, MLXXX said:

Audio files compressed with the mp3 codec differ in the noticeability of the artefacts depending on a number of factors including:

  1. the bitrate (128kbps being much more susceptible to creating audible artefacts than 320kbps)
  2. the nature of the music (e.g. complex orchestral music can be harder to encode successfully than simply textured music)
  3. whether an uncompressed version of the same music is available for immediate comparison.

 

Maybe also the quality of the encoding software?

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30 minutes ago, MLXXX said:

As for 128kbps stereo AAC, I find that a distinct improvement over 128kbps stereo mp3.

 

and the higher the bitrate, the less distinct that improvement will be. 

 

I am surprised at the low quality some commercial radio stations use at time.  Judging from the audible artifacts it sounds like 128k or worse.  Noone should be using low bitrates like this anymore.

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26 minutes ago, aussievintage said:

I am surprised at the low quality some commercial radio stations use at time.  Judging from the audible artifacts it sounds like 128k or worse.  Noone should be using low bitrates like this anymore.

DAB+ radio in Australia commonly uses 64kbps nominal (which is less than that for the actual HE- AAC audio after deductions for error correction, and slides). Digital radio, as implemented in Australia, has generally favoured a high number of program services over high audio quality.

 

I have found television sound using mp2 distinctly irritating. It is much less efficient than mp3. Mp2 has been used particularly for Standard Definition TV broadcasts. For my ears, the old analogue broadcasting FM sound used for television was better.

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4 hours ago, MLXXX said:

DAB+ radio in Australia commonly uses 64kbps nominal 

 

and you can hear it, very obviously at times.   I have also heard it on AM stations (obviously using source files that are compressed) - as bad as they are fidelity wise - the whispery treble artifacts shine through.

 

4 hours ago, MLXXX said:

I have found television sound using mp2 distinctly irritating. It is much less efficient than mp3. Mp2 has been used particularly for Standard Definition TV broadcasts. For my ears, the old analogue broadcasting FM sound used for television was better.

What bugs me on the television is the contour patterns in the sky at times due to low bandwidth compression.

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HI All,

 

I got 3 out of 6 correct, the other 3 were the 320khz tracks, but as I am in my latish 60's I think that is not tooooooo bad 😀

 

The Neil Young track was the most difficult due to the softness in presentation, the ones I got correct seemed to have more 'body' to them.

 

JJ

Edited by Janjuc

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36 minutes ago, Janjuc said:

I got 3 out of 6 correct, the other 3 were the 320khz tracks, but as I am in my latish 60's I think that is not tooooooo bad 😀

3 out of 6 means it was purely random chance...

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26 minutes ago, Ittaku said:

3 out of 6 means it was purely random chance...

Again?    There were 3 choices, random chance is 33%

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