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No difference between 128 and 320.

Discussion in 'Sound Science' started by xinze, Sep 21, 2012.
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  1. eahm
    The magic comes when you try AAC or Opus and you go down to 64kbps with some songs and you don't hear the difference with good headphones. Then you cry.
  2. bigshot

    What hissing noise?
  3. joeyjojo
    All the impedance does is change the distribution of voltage and current.
    What will make a difference is the sensitivity of the headphones. High sensitivity headphones will reveal more noise as the SNR ratio suffers (think IEMs plugged into a noisy front panel audio socket on a computer. The whining noise has a constant power, which turn into a much larger SPL through sensitive earphones than low sensitivity ones).
    This is a constant noise though, not for "artefact hunting". There's no reason I can think of for one headphone to be more revealing of compression artefacts than another.
  4. BoxerOrBag
    can somebody please tell me if this site's test is accurate/fair?
  5. mikeaj
    I think for mp3 and some other formats and encoders, the artifacts are mostly high frequency.  A treble-tilted headphone would make those things easier to hear, with less auditory masking of the problems I guess.
    With a low enough bitrate and certain preset and young enough ears, you could detect the presence of the lowpass filtering, which should be easier with headphones with good treble extension.
  6. stv014
    It seems to be so mostly, other than the minor level mismatch noted below. Also, the delay before playing "X" is relatively long, but maybe that is intentional.
  7. xnor
    Yes it is.
  8. stv014
    I found some level difference (a few tenths of a dB) between the pair of files I downloaded.
    Edit: I tried another pair of files, and the 128 kbps version is again slightly quieter.
  9. Lorspeaker
    errrr.....do u think a dedicated dac would help u separate between the diff resolution?[​IMG]
  10. stv014
    The DAC on the card degrades the signal much less than 128 kbps MP3 compression, probably not even audibly at all, so most likely no. Although maybe some "audiophile" DACs distort the sound in a way that somehow makes the difference more noticeable. [​IMG]
  11. BoxerOrBag

    THANK YOU very much [​IMG].
    On a completely unrelated note, I'd just like to mention that while I've just recently made my account, I have been browsing this forum for close to a year now. I would now like to take the opportunity to thank all the gracious folks who's been sharing the knowledge on the Sound Science forum, it really helped me learn about not just the gear, but my senses as well.
  12. xnor
    Slightly quieter in rms level but actually louder (EBU R128 loudness). My guess is that the guy that created the files used a ReplayGain scanner to normalize the volume.
  13. stv014
    I have now checked the files with ReplayGain in foobar2000, but it also shows the 320 kbps version as being a few tenths of a dB louder.
  14. xnor
    Yes, fb2k switched to a r128 compliant loudness scanner some versions ago. For example the 320 kbps Gino D'Auri track needs 0.37 dB more attenuation than the 128 kbps version to have equal loudness. One would have to check with an older fb2k version or mp3gain to see if they were normalized at all or based on the old proposed RG standard.
  15. streetdragon
    i got pretty interested after reading this article

    free download link is here available in FLAC and others http://wolfgun.bandcamp.com/track/voyager

    so I decided to run a little blindtest on myself, i took this song in FLAC into sound forge and saved it as:
    FLAC x1
    320mp3 x2
    128mp3 x2
    32mp3 x1
    HighVBR x1
    MediumVBR x1
    LowVBR x1

    placed them into winamp and randomized them, and did a blind test
    guess answers on the left, real answer on the right

    128mp3/MVBR - HVBR
    320mp3/FLAC - 128mp3
    128mp3/MVBR - FLAC
    320mp3/HVBR - 320mp3
    128mp3/MVBR - MVBR
    LVBR               - LVBR
    32mp3             - 32mp3
    320mp3/HVBR - 320mp3
    MVBR/128mpr - 128mp3

    i was quite surprised at the results, especially when i mixed up FLAC for 128mp3 and 128mp3 for HVBR

    test run on a Dell inspirion 1525, Hippo box amp and a Sennheiser HD558 modded,250band eq used

    so it is actually quite difficuilt and almost impossible to differenciate 320mp3 and 128mp3
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