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What kind of Ultrasonic Frequencies are in HD Tracks?

Discussion in 'Sound Science' started by bigshot, Jul 31, 2018.
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  1. bigshot
    One funny story... Last night I may have run across another disc with super audible noise at high volumes. I got the new Japanese SACD of the quadraphonic mix of Miles Davis's Bitches Brew. I put it on and my dog settled in at her normal spot lying between the speakers. Suddenly she leaped to her feet, spun around three times and dashed out of the room. She didn't come back until the album was over.

    Either it was ultra high frequency noise, or she doesn't like fusion...
  2. Arpiben
    Poor dog! Digitally Low Pass filter and sure she will not move next time unless she doesn`t really like fusion.
  3. bigshot
    Thanks for the examples Rrod and Arpiben!
    RRod likes this.
  4. 71 dB
    For her fusion is confusion.
  5. gregorio
    I've been saying that for years, well over a decade. Consumer distribution has moved on to higher and higher sample rates, marketing it as more accurate and/or as capturing more of the "real" sound but that's all it is, marketing! Absolutely ALL eventualities, including ANYTHING that may happen downstream, is MORE THAN covered by 24/48 and that's not just for music but for all audio. Beyond that point it's all downhill, not uphill as suggested by marketing.

    1. Of course "above 20kHz spikes and other noise" is avoidable in real world situations, what a ridiculous thing to state. Simply choose a 44.1kHz PCM sampling rate and everything above 20-22kHz is COMPLETELY avoided!
    1a. How do you propose to "watch for and avoid" it? Your solution makes no sense, record everything up to about 1.4Mhz and then what, how can you "watch for" anything above 96kHz? And, between 20kHz - 96kHz how does "watching" help, how can you tell from "watching" what is noise and what *might* be musical material? And, even if you do spot some obvious interference or noise, how do you propose to remove it, aren't you going to filter it out? Why don't you apply a bit of logic and filter it out to start with?

    2. Why imagine that, why would one use different mic pre-amps from at least two manufacturers?

    3. Why makes you think 20/30 years and older equipment had better power handling than today's pro equipment? Maybe if you compare top of the line vintage gear with today's cheap amateur/pro-sumer gear then in *some* cases the vintage gear might have the edge. Of course that's a nonsense comparison though, by definition commercial/professional recording studios are not based on cheap amateur gear!

    4. What do you mean "some of the noise will come through"? Absolutely ALL of the noise will come through! You don't seem to understand what CMR is or what it does. CMR does NOT reduce/reject noise, it only rejects Common Mode noise, IE. Noise/interference introduced to the XLR connectors (and the cable between them) that is common to the hot and cold connections. Any noise before or after, such as recording venue noise/interference and mic and mic pre-amp self noise, is completely unaffected!

  6. Zapp_Fan
    Came here to basically say this. Filter out the ultrasonics and frequency shift them down to hear what we're subjecting our poor dogs and cats to. In all seriousness it would be interesting to judge by ear whether the ultrasonics would be desirable even supposing you could hear them clearly.

    I can do this if nobody else wants to, but I don't think I have access to any 'offensive-looking' 192khz tracks.
  7. bigshot
  8. Zapp_Fan
    OK sorry about that, I got confused between the sound science and this thread.

    Just tried the same thing on this jazz track (filter @ 20khz) - the transients come through really clearly, you can tell drums from cymbals at least. It sounds really distorted and crappy, but that's only to be expected when pitching the audio down so much.

    Still, for me it's clear this is audio that "belongs" in the recording and I even think it's plausible (if far from proven) that it could make a difference in what the listener hears.

    If you consider it just in terms of time domain and total energy, transients will have a higher total amplitude if they include ultrasonics. In other words you have a higher air density hitting your ear if the ultrasonics are there. I don't *think* (nor do I know for sure) you need to be able to perceive tones beyond 20khz to notice a higher SPL during a drum or cymbal attack. But let's be clear, what I am talking about is detecting differences in amplitude, not hearing ultrasonic tones. BIG difference. (someone correct me if this has already been debunked somehow)

    Of course this is assuming you have transducers (let alone DACs and amps) that deliver this content to your ear without issue, which most won't. But at least we know there is something there that originates with the recording and isn't just complete nonsense.

    Now I know bigshot is going to follow up with "well the amplitude is so low it's hard to imagine anyone could REALLY hear the difference, plus nobody has ever measured audibility reliably, plus most systems won't handle it properly, plus almost all recordings are mostly garbage over 20khz" which is all true. But I still think it's interesting.
  9. Steve999
    Yeah, I almost felt guilty about stating that jazz drums could get you to 24 khz on the sixth-order harmonics, at least according to the reference materials I looked at. But that's what I read and they weren't even trying to make any kind of point, it was just comparing frequency ranges and harmonics of different instruments. I for one am never going to hear that. Nor do I believe anyone else will. When you find the guy (or girl!) that can I will say hey, good for you, that's truly a gift and truly incredible, but give it five or ten years.
    Last edited: Nov 15, 2018
  10. bigshot
  11. Steve999
    First I made sure my $30 headphones could likely reproduce the full range of any sound at issue (bragging rights here!):


    I waited for the heat to shut off.

    Then I made sure my $70 DAC could do 22khz. It said it could go out to 50 khz. But I have a feeling that's just the analog stage, not the DAC.

    Then I tried another DAC.

    But I gotta tell you, for this, whatever it is, I didn't hear a thing.


    And then my son started practicing the piano and that was that . . .
  12. Steve999
    I'll try some Chick Corea and Herbie Hancock with our dog tonight. . .
  13. Glmoneydawg
    Damn it man !...not herbie!
  14. Steve999

    I'll report back when our dog drops by. By the way, this makes a super-cool comparison with the "classic" Herbie Hancock Watermelon Man recording.
    Last edited: Nov 15, 2018
  15. Arpiben
    How much are you estimating that ultrasonic gain?
    What about the effects of ultrasonic huge amount of energy produced by noise shaping then?
    Depending on how ears filter the added ultrasonic energy should be insignificant.
    castleofargh likes this.
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