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hypersonic effect discussion

Discussion in 'Sound Science' started by kiteki, Jul 6, 2011.
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  1. kiteki






    [​IMG]^Note: This is testing linearity from 6kHz - 100kHz with three different driver materials, the black line is Polyethelene / Polyimide  successive layering.

  2. nick_charles Contributor
    1. Qualitative evaluation of Wave Field Synthesis with expert listeners
    2. Improving the sound quality of recordings through communication between musicians and sound engineers
    3. Subjective Evaluation of MP3 Compression for Different Musical Genres

  3. kiteki
    Ok... I still need to read the paper like... five times... have you read this part?
    "It should also be noted that all the files used in this
    study were recorded and presented in 24 bits. Thus,
    we were not comparing the CD standard (i.e.
    44.1 kHz, 16 bits) with high-resolution formats but
    restricted our experiment to sample rate
    discrimination. This choice was based on the fact that
    limitations of bit-depth of the CD standard at 16 bits
    have been identified and documented [10]. Therefore,
    differences between CD standard and high-resolution
    audio formats should be easier to detect than the
    differences observed in this study."

    So they intentionally selected 24/44 versus 24/88, since they think 16 bit is too easy and already documented?
    They reference
    "[10] Stuart, J., “Coding for high-resolution audio
    systems”, J. Audio Eng. Soc., vol. 52(3),
    pp. 117-144. (March 2004)"

    Edit: http://www.meridian-audio.com/w_paper/Coding2.PDF
  4. nick_charles Contributor
    Yes I read that part. Bob Stuart http://dhantalradio.com/bt/aes/Journal%20AES%20Vol%2052%20No.%203.pdf does a fine job of describing measurable issues with 16/44.1 but he starts with a bias. He is the head man at the Acoustic Renaissance for Audio (ARA) a bunch fully committed to high res PCM encoding (and very anti-DSD as well fwiw) , so far from bias-free.
    Stuart however insists on noise-free playback at 120db at the listening position of pure sine waves (roughly equivalent to having an ambulance siren in the room with you) as the only acceptable standard.
    However his paper does not support his assertions with empirical listening tests so cannot be used as proof that the CD standard limitations are intrinsically audibly detectable below absurd volume levels. The limitations of CD at very high volume levels with null signals is something which M and M tell us as about anyway.
  5. Head Injury
    Just the materials, not the drivers themselves? I'd like to see the drivers in action.
    The first graph only appears to go up to 20 kHz, like a typical graph or headphone. The second graph has no labeled axes. The third and fourth have no labeled scale on the vertical axes. I don't even know what the fifth is trying to represent because of the poor resolution and grid lines obscuring everything. The last graph suggests that Sony does not make use of hypersonic frequencies, because of the roll off to 20 kHz. And that graph is of an actual headphone, not just driver material.
  6. kiteki
    Lol, you are correct there.  The last graph isn't from Sony, it's from "mister_terch" it looks like.  For some reason when measuring IEM's it's very difficult to capture what's above 10kHz accurately, that site goldenears says 100Hz to 10kHz is their "safe zone".
    The fifth one is from Sony's development, they are testing drivers of different material, not only driver material.  The significance is they found polyethelene / polyimide / polyethelene (PET-PI-PET) layering to have a nicer respone up at, err... well all the way up to 100kHz.  That's not for 22kHz->100kHz listening though, it's just to test how the driver material performs overall, it's a pretty complicated process to layer PET-PI-PET several hundred times in opposite directions just to make a successful multi-layer driver, then they used it in the Sony EX700 IEM which had limited success.
    I don't know why Sony didn't provide FR data from their labs on the SA-5000 or Qualia drivers, surely the customers would like to know the specs are real?  Perhaps it's in a Qualia pamphlet somewhere.
    To be honest if the hypersonic effect is real it's unlikely you can hear it in a headphone and more likely to exist via speakers.  The 'most' scientific explanation is it enters your eyeball.
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