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  • High Frequency Hearing and Mixing

    I was using a tone generator to check the functioning of some 3 way speakers and noticed the SPL output really dropped off above 13kHz.  I wanted to quantify this so I  measured the output with EASRA and a DBX measurement mic and the output did drop off somewhat above 13kHz, but only by about 3 -6 dB all the way to about 18kHz.  

    I then cranked up the mixer output a bit and listened right by the measurement mic. It appears  it was my hearing that was dropping off.  This was at about 95dB A fast in a basement shop, loud enough where the lower frequency tones were somewhat uncomfortable.  So Fletcher-Munson nothwithstanding, I think about 13kHz is the upper limit of my hearing.


    Well this is a little disheartening because sometimes I find myself twiddling EQ knobs in the 15kHz range and thinking I am hearing something.  Like I am cutting some really high frequency hiss or, alternatively  like I am adding "shimmer" or "sparkle".   I think my brain might be playing tricks on me that I actually hear a difference. Or maybe the 16kHz EQ filter on the ASHLY MQX2310 has a wide overlap.

    So my rather nebulous question is whether there are subtle nuances that you can you sense with respect to EQ changes at the higher frequencies or is it just my imagination?

    The other question is how likely is it that the average audience member at rock sort of event would have good hearing at frequencies above 13kHz?  I hate to think I was making big changes that everyone could hear but me.

    --Mike<br><b>&quot;</b><i>If your not confused, you don't know what is going on</i><b>!&quot;</b><br><br>Live Sound for the Mt. Shasta area<br><a href="http://www.shastalivesound.com">ShastaLiveSound.com</a><br>

  • #2

    First of all, you need to use an unweighted measurement for any SPL levels

    Second, 3dB down at 18kHz is generally quite excellent, even 6dB down might be quite good depending on the HF lift correction being used (or not used) With powered speakers with DSP, -3dB at 18kHz is kind of the general target.

    Yes, you will find that your HF hearing is unlikely to be flat at 18kHz, and even 13kHz. I have a hearing test every 2 years to keep a check on any changes and so far I'm doing very well. You might want to do this as a benchmark against future changes.

    Comment


    • WynnD
      WynnD commented
      Editing a comment
      As far as things the audience might notice that are above 13K htz, female voices and cymbals come to immediate mind. (Cymbals mostly. You lose a lot if the high end in a mic'd drum situation isn't good.)

  • #3

    When I'm not booked for sound gigs, I sometimes go hear bands at different venues to listen to the mix and see how other engineers approach their mixes.  Often when I walk in, the overall tone of the mix strikes me as pretty harsh and bright.  My theory is that there are a lot of sound guys with some significant hearing loss in the higher frequency ranges.  So they tend to EQ the mix to what sounds 'good' to them, but to those with normal/better hearing, is actually pretty harsh.  

    I know that 'threshold shift' can occur after a while, but even allowing for that, I sometimes can't stay too long, as it is just too hard to tolerate the way the mix sounds.  I sometimes wonder if it's just me, or do other sound guys come across this too?

    Comment


    • Bugzie
      Bugzie commented
      Editing a comment

      I've questioned my hearig for quite a few years. Working at an airport I can be subjected to high SPL's on occasion. As a result I've been going to an audiologist at least once a year. Odd thing I found was that I hear high freq's better than I should. As a result I have to be careful when setting up the house mix. I've been told that I needed more highs on more than one occasion. So I adjust and find that I need ear plugs as I find that the sound is quite shrill to my ears. Everyone else likes it so I grab my trusty foam ear plugs. Funny thiing is that I don't like the over emphasized bass that others do either. But "the boss is never wrong."


    • Craig Vecchione
      Craig Vecchione commented
      Editing a comment

      There's not much musical source at 18k, even 13k is approaching the limits of cymbal "shimmer". Thinking you hearing a change when adjusting sliders is a pretty accurate assessment, as you hear more hiss and sibilance than music fundamental or overtone.


  • #4
    I'd like to add a couple of things to this discussion. First are you assuming that your DBX mic is flat above 13khz? I would bet its down quickly above it so the amount of difference you are attributing to your measurements may likely only be half of that.

    Second you need to think in terms of octaves and not single frequencies. Think pink noise not white noise for example. The difference between say 13k and 15k may be 2000 Hz but its only a small part of an octave. The perception of HiFi sound is thought to relate to balance. So the you have the same number of audible octaves above 1k ( the center of human hearing). Typically you don't have a bunch of frequencies ( again in terms of an octave below 40 Hz so as long as it is fractionally balanced above 10k it should sound HiFi balanced.
    Don Boomer

    Comment


    • agedhorse
      agedhorse commented
      Editing a comment

      dboomer wrote:
      I'd like to add a couple of things to this discussion. First are you assuming that your DBX mic is flat above 13khz? I would bet its down quickly above it so the amount of difference you are attributing to your measurements may likely only be half of that.

      Second you need to think in terms of octaves and not single frequencies. Think pink noise not white noise for example. The difference between say 13k and 15k may be 2000 Hz but its only a small part of an octave. The perception of HiFi sound is thought to relate to balance. So the you have the same number of audible octaves above 1k ( the center of human hearing). Typically you don't have a bunch of frequencies ( again in terms of an octave below 40 Hz so as long as it is fractionally balanced above 10k it should sound HiFi balanced.

      I agree, it's always a good idea to verify that the measurement tools are accurate. Don's comment about the flatness of that particular mic matches my observations very closely.


  • #5
    Compare to a known calibrated mic is one was to improve confidence.

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