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Thread: Measurements, EQ, and what we actually hear

  1. #1
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    Default Measurements, EQ, and what we actually hear

    Following a suggestion from curtis, I'm starting a new thread to discuss this topic.

    I use a series of 1/12th octave test tones when trying different speaker placements/positioning, and it's very correlated with what I hear with music. I'll usually listen to music for a while, and see what sounds different, then listen to the test tones after that.

    The clear exception is with room modes - they don't show up on the test tones, but show up on plucked double bass. For those, I rely on a room mode calculator and our piano. I can generally find the note that's more resonant than it should be on the piano.

    That's why I'm leaning towards getting a precise parametric equalizer like the Behringer, fine tuning the response a bit, so that the frequency response is extended and even more neutral than it is now. I'm not imagining I'd change a lot - just boost the low bass a bit, tame a room mode or two, and bring down the 500-1000Hz rise a little bit.

    I lean towards less intervention rather than more.
    Last edited by James; 04-18-2022 at 10:07 AM.

  2. #2
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    Default Re: Measurements, EQ, and what we actually hear

    But then I've come across the REW, which seems much more complex and sophisticated than what I'm doing, but seemingly less correlated to what people actually hear.

    So I'm interested in anything people want to share about using it. Especially if/when the measurements don't correlate to what you hear - how do you make sense of that?

  3. #3
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    Default Re: Measurements, EQ, and what we actually hear

    "REW is free software for room acoustic measurement, loudspeaker measurement and audio device measurement. The audio measurement and analysis features of REW help you optimise the acoustics of your listening room, studio or home theater and find the best locations for your speakers, subwoofers and listening position."

    https://www.roomeqwizard.com/

    I have used REW. In general, ALL audio measurements (frequency response, harmonic distortion, impulse response, waterfall plots, etc. etc.) are difficult to correlate with "what people actually hear". But you can learn a lot from REW measurements of your audio system, and how your system interacts with your listening environment, that you can't learn from "just listening".

    I think REW provides an amazing range of audio measurement capabilities considering that it's freeware, although it does of course require some hardware to work, such as a USB measurement microphone and a Windows laptop computer with an HDMI connector (if your AVR or audio processor has HDMI inputs).

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    Default Re: Measurements, EQ, and what we actually hear

    Yes, it looks like very impressive software, and I'm also kind of amazed that it's offered for free. But I'm puzzled by the differences between measurements and listening.

    For example, merrymaid520 posted some REW measurements (I believe they're the ones with the adjustments made to more accurately reflect the way people hear) on page 52 of the LX thread.

    They show what look like large deviations from neutrality to me, and yet merrymaid says they sound neutral.

    Would you expect to hear those deviations in your system? And/or would you expect those measurements to correlate with what you hear with test tones?

    I'm not trying to pick on merrymaid - those are just the easiest REW measurements for me to find.
    Last edited by James; 04-18-2022 at 01:55 PM.

  5. #5
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    Default Re: Measurements, EQ, and what we actually hear

    Quote Originally Posted by James View Post
    Yes, it looks like very impressive software, and I'm also kind of amazed that it's offered for free. But I'm puzzled by the differences between measurements and listening.

    For example, merrymaid520 posted some REW measurements (I believe they're the ones with the adjustments made to more accurately reflect the way people hear) on page 52 of the LX thread.

    They show what look like large deviations from neutrality to me, and yet merrymaid says they sound neutral.

    Would you expect to hear those deviations in your system? And/or would you expect those measurements to correlate with what you hear with test tones?

    I'm not trying to pick on merrymaid - those are just the easiest REW measurements for me to find.
    A few things:
    The room has a lot to do with the FR measurements. FR is not the only thing that determines how a speaker sounds. Trying to correlate what one hears in their room to what someone else will hear in their room is a lost cause.
    Those deviations are not that big. You don't listen to test tones when listening to music as you are listening to harmonics(which is what gives you the difference in sounds of instruments or voices) as well.
    Lastly, people have to understand the deficiencies in their own hearing, as well as understand measuring equipment is much more sensitive to our hearing.
    I am very skeptical when someone can be specific to what they are hearing before they look at an FR graph or any other measurement for that matter. But hearing something, and then going back at looking at measurements to verify, that is more credible.
    Last edited by curtis; 04-18-2022 at 02:44 PM.
    -curtis

  6. #6
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    Default Re: Measurements, EQ, and what we actually hear

    Yes, rooms are very important - I get that part. I didn't mean would you hear the same thing as merrymaid - I meant if you had a set of REW measurements like that, would you expect to hear deviations from neutrality.

    What qualifies as a big deviation from neutrality? I see what looks like about a 15db difference between 100Hz and a bit over 200Hz. Will most people not hear that?

    Yes, with music we hear many frequencies at the same time.

    Would you expect that the REW measurements correlate with listening to test tones? Or would they be different, and if different, how would you explain that difference?

  7. #7
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    Default Re: Measurements, EQ, and what we actually hear

    Quote Originally Posted by James View Post
    Yes, rooms are very important - I get that part. I didn't mean would you hear the same thing as merrymaid - I meant if you had a set of REW measurements like that, would you expect to hear deviations from neutrality.

    What qualifies as a big deviation from neutrality? I see what looks like about a 15db difference between 100Hz and a bit over 200Hz. Will most people not hear that?

    Yes, with music we hear many frequencies at the same time.

    Would you expect that the REW measurements correlate with listening to test tones? Or would they be different, and if different, how would you explain that difference?
    First, define what you mean by neutrality.

    That 100hz to 200hz difference is caused by the room, and it is high peak to low peak, and those peaks are narrow. I think one would be hard press to hear the difference with a sliding sine wave tone.

    I do think REW would give a good general idea of how a speaker sounds in-room, but not as specific as you make it out to be.
    -curtis

  8. #8
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    Default Re: Measurements, EQ, and what we actually hear

    Well, absolute neutrality would mean a completely flat frequency response, I would think.

    I picked that one because it's the biggest - there are also a lot of other smaller ones as well. Would you expect the approximately 8db difference between 90 and 100Hz to be audible?

    What about the 1/12 octave test tones that I use? They're not a sine wave sweep.

  9. #9
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    Default Re: Measurements, EQ, and what we actually hear

    Quote Originally Posted by James View Post
    Well, absolute neutrality would mean a completely flat frequency response, I would think.
    That is an incorrect statement.


    Quote Originally Posted by James View Post

    What about the 1/12 octave test tones that I use? They're not a sine wave sweep.
    Test tones are, in fact, sine-waves, what frequency test-tones are you using?
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    David Fabrikant
    www.ascendacoustics.com

  10. #10
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    Default Re: Measurements, EQ, and what we actually hear

    Quote Originally Posted by James View Post
    Yes, it looks like very impressive software, and I'm also kind of amazed that it's offered for free. But I'm puzzled by the differences between measurements and listening.

    For example, merrymaid520 posted some REW measurements (I believe they're the ones with the adjustments made to more accurately reflect the way people hear) on page 52 of the LX thread.

    They show what look like large deviations from neutrality to me, and yet merrymaid says they sound neutral.

    Would you expect to hear those deviations in your system? And/or would you expect those measurements to correlate with what you hear with test tones?

    I'm not trying to pick on merrymaid - those are just the easiest REW measurements for me to find.
    James,

    The background of my entire career in this industry is to try and correlate what we hear with measurements, and I am still not there - nor do I suspect this industry will ever be. We all hear differently and the biggest mistake one can make is to trust one's own hearing.

    As measurement technology improves, so does our ability to at least make an estimate as to what we can expect to hear. Your method of using sine-wave test tones combined with an SPL meter to try and determine how a speaker measures (ie sounds like) is very flawed, and a method that was thrown away over 30 years ago.

    First off, sine wave test tones excite only a specific frequency, so unless you are able to run 1/12th octave test tones (12 test tones per each octave), your data is basically not usable.

    Second, sine wave test tones are steady state signals, they are not music and can actually be quite damaging to a speaker (especially a ribbon tweeter)

    Third, with using your SPL meter to measure ( I assume this is actually a calibrated spl meter, hopefully not an app on a mobile device) - the only thing you are somewhat accurately measuring is the acoustics of your room (and even that is questionable), not the speakers. (this is why this method was thrown in the dumpster so long ago)

    And finally, and I must stress this - please do not trust your hearing to even attempt to estimate an actual frequency response measurement. There is nothing more inaccurate than your own hearing and it will take you many, many years of critical listening experience combined with understanding how to take accurate measurements and understanding of the differences between an in-room response and an anechoic response.

    My advice to you, throw out all of your current assumptions regarding audio measurements, read as much as you can about using REW (it is a good place to start) and most importantly - about how to interpret those measurements.

    Hope this helps!
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    Good Sound To You!

    David Fabrikant
    www.ascendacoustics.com

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