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Device for Equal Loudness/Fletcher Munson Curve? Do Any Speakers Adapt to This?

dasdoing

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Will a piano being played at a distance farther from me (lower SPL) have adjusted its frequency response for my relative location?

it would sound totaly diferent from turning volume knob down

I've played with the curves, didn't find them personally useful, and don't worry about it.

If you do, that's fine.

you position is totaly fine, too
two things though:
a) If you like a song that suddenly plays wont you turn the volume up? Do you do so in order to compansate for background noises? No, you want to hear it balanced
b) why do people put smiley curves on their EQs? why they put (descending) house curves on their correction? because 83dB is pretty loud and most hear on lower volume. there is obviously a natural desire to compansate for the lost balance
 

Aerith Gainsborough

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I have a (probably dumb) question regarding this topic:

People mentioned ~83dB as the level at which the human ear has the most balanced frequency response.
So if you listen critically at this volume, does that mean the peaks of the piece in question are at 83dB or does that SPL refer to the RMS value?
 

dasdoing

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I have a (probably dumb) question regarding this topic:

People mentioned ~83dB as the level at which the human ear has the most balanced frequency response.
So if you listen critically at this volume, does that mean the peaks of the piece in question are at 83dB or does that SPL refer to the RMS value?

the 83dB level was not chosen this way. they tested levels in a movie theater and asked the audience until they found a level everybody liked afair.
the way you set up this level is with pink noise.
read here (though I personaly think the -20 level is missinterpretation) https://www.audiosciencereview.com/...ference-sound-pressure-level-flowchart.11069/
 

Pluto

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Is there a device that will change the frequency response of a system to match [equal loudness contours] at normal listening levels?
I remember some colleagues and I being given an analogue equal loudness "correction" unit to try, years ago. It was inserted before the studio power amps and had to be calibrated according to the amount of gain (i.e. sensitivity) in the amplifier/loudspeaker system. You then adjusted the volume level on this box instead of the usual control.

The effect was unsettling. Why? Well, we studio engineers (who were not psycho-acoustic experts) surmised that humans live with the equal loudness effect from birth and unconsciously ‘compensate’ for it quite effectively. We get used to quiet audio having less bass (and, to a smaller extent, less top) and that somehow seems normal and what the ear/brain expects. When you introduce a volume control that, in effect, defeats one of the fundamental characteristics of human hearing in favour of being more “technically correct” it seems all kinds of things go awry.

The gadget remained in situ for about a week and during that time, not one job was evaluated as having the ‘right’ spectral balance. So the box went into the cupboard under the stairs along with all the other failed experiments…
 

dasdoing

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I remember some colleagues and I being given an analogue equal loudness "correction" unit to try, years ago. It was inserted before the studio power amps and had to be calibrated according to the amount of gain (i.e. sensitivity) in the amplifier/loudspeaker system. You then adjusted the volume level on this box instead of the usual control.

The effect was unsettling. Why? Well, we studio engineers (who were not psycho-acoustic experts) surmised that humans live with the equal loudness effect from birth and unconsciously ‘compensate’ for it quite effectively. We get used to quiet audio having less bass (and, to a smaller extent, less top) and that somehow seems normal and what the ear/brain expects. When you introduce a volume control that, in effect, defeats one of the fundamental characteristics of human hearing in favour of being more “technically correct” it seems all kinds of things go awry.

The gadget remained in situ for about a week and during that time, not one job was evaluated as having the ‘right’ spectral balance. So the box went into the cupboard under the stairs along with all the other failed experiments…

is there a natural way of hearing an attenuated recording?
let's take a recording of an orchestra with a totaly flat mic. it will sound natural if you reproduce it at the exact same loudness level the mic "heard". if you change the level it can't sound natural anymore.
now, since you are an engineer. what if the mastering reference level for some reason was 60dB? the level would be lower than what was "heard" by the mic. would or wouldn't you equalize the balance in the master to compensate for that?
 

Pluto

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if you change the level it can't sound natural anymore
That is where I disagree… I think!

The ear-brain seems remarkably adept at dealing with the consequences of the equal loudness contours without getting too worked up about it. If I listen to an orchestral recording, I need to adjust the volume a long way before I'm left with any real sensation that there's a worrying spectral imbalance.

In other words, the ear-brain seems to accept that quieter listening entails less bass and treats that as normal and correct. I have known dozens of engineers whose preferred listening level varies from the barely audible (“I don't want to f**k-up my hearing”) to war-zone (LETS ROCK’N’ROLL). Yet, when scrutinized, the spectral balance produced by both is about right.

How could this be, unless the ear-brain has a very highly-refined system of dealing with the equal loudness contours and compensating this so-called problem that just doesn't seem to be much of a problem in real life!
 

dasdoing

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That is where I disagree… I think!

The ear-brain seems remarkably adept at dealing with the consequences of the equal loudness contours without getting too worked up about it. If I listen to an orchestral recording, I need to adjust the volume a long way before I'm left with any real sensation that there's a worrying spectral imbalance.

In other words, the ear-brain seems to accept that quieter listening entails less bass and treats that as normal and correct. I have known dozens of engineers whose preferred listening level varies from the barely audible (“I don't want to f**k-up my hearing”) to war-zone (LETS ROCK’N’ROLL). Yet, when scrutinized, the spectral balance produced by both is about right.

How could this be, unless the ear-brain has a very highly-refined system of dealing with the equal loudness contours and compensating this so-called problem that just doesn't seem to be much of a problem in real life!

how do you explain smiley-eq curves and housecurves for room correction which most people tend to like? isn't his related to the fact that most people will playback stuff at quieter then reference level?

on a sidenote. since you are an engineer can you have a look at this? https://www.audiosciencereview.com/...sure-level-flowchart.11069/page-2#post-416499
 

maverickronin

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I'm going to go Cherry Picking and note that Toole recommends the use of tone controls for bass for just this reason...

On a personal note, after experiencing the dynamic loudness compensation on my RME ADI-2 DAC I can never go back to something without this feature. It makes low volume listening so much more satisfying.
 

Pluto

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how do you explain smiley-eq curves and housecurves for room correction which most people tend to like?
It's all Dolby's fault. Whether you love or hate the proprietary regime they established, and still largely control, they did have the clout to convince most movie theater owners that the audio had to be brought up to a certain minimum standard.

I don't really seek to explain anything that "people tend to like". Room curves became a way of allowing Dolby to set a number of standards in an attempt to bring the then-abysmal sound quality in the average movie auditorium up to a level of reasonably consistent mediocrity. The only standard hitherto dated from the late 1930s, the "Academy Curve" which was designed to ensure maximal speech intelligibility from noisy optical tracks and wasn't interested in much below 80Hz or above 8kHz.

The equal loudness curves have their big upturn at low frequencies that barely exist in nature: our hearing evolved the way it did for, presumably, good evolutionary reasons – mainly to maximise our sensitivity to human speech but to hear approaching predators, stuff like that. Up to about 400 years ago (no time at all in the evolutionary scheme of things), most people hardly ever heard anything below 200Hz. Likewise, most people went from birth to death without experiencing a sound pressure much over 85dBA! Contrast that with the SPL and LF assault to which we are sometimes subject these days.

When you are creating a sound track that varies drastically from real life (which is why people like movies!) it helps to have decent calibration i) for consistency in dodgy venues operated by largely unskilled staff and ii) to know what hardware is required to do the job and make the task of equipping the average high street movie theatre as formulaic as possible and iii) to satisfy the egomaniacal director that his work would be as well-represented in the Grimthorpe Curzon as in the Grauman Chinese Theater.

Reference curves tend to exist because of the artificially high level of extreme LF in many films where the ear is operating a long way from its normal LF parameters. The idea is that the film is shown at, more or less, the level it was mixed at and, therefore, you get the sound that the director intended. It stands to reason that the whole concept of reference levels is more important to a movie about the destruction of worlds by massive weapons than it is to a film about the relationship between Granny and her poodles.

The other major purpose served by reference levels is to keep the volume of the main dialogue reasonably consistent, because the audience tends to prefer the dialogue about the destruction of worlds to be at roughly the same volume as Granny talking to her poodles, particularly on TV where one may follow the other within a few minutes.
 

Pluto

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can you have a look at this?
Like I said earlier, while there exists the need to keep things under control in a complex chain, my gut says that we humans are really quite good at compensating for volume changes without the need for curves and calibrations. Likewise, we tend to set our volume to suit the material and the occasion. Assuming 'serious' i.e. not background, listening one is likely to set an orchestral concert to peak at about 94dBA and the radio play about Granny's poodles no higher than, say, 78dBA when the massive German shepherd who lives across the road barks aggressively.
 

Aerith Gainsborough

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the way you set up this level is with pink noise.
read here (though I personaly think the -20 level is missinterpretation) https://www.audiosciencereview.com/...ference-sound-pressure-level-flowchart.11069/
Thank you for taking the time to reply.
Not sure about this calibration mumbo-jumbo using DAW input but I exported the pink noise @ -20dB from REWs generator and fed it to foobar while measuring at the MLP with the UMIK-1.

With my usual playback settings I measured ~50dB(C) or ~48dB (A).
When I pushed the volume at the AVR until I measured 78dB (A) it was very loud. Do people really listen to music at that level for enjoyment? The pink noise was so loud, that I did not dare to put on any actual music. Sunday evening here, my neighbors would not like that one bit, will try briefly during a work day, but I doubt that this SPL is sustainable for more than a minute unless you live in your own house. Not to mention that I'll probably feel as if my ears are about to fall off.

So if I am interpreting the curves in the OP correctly, I would need to "boost" the bass (or rather attenuate the other frequencies in order to avoid clipping) to around 75dB when the midrange is at 50dB in order to perceive the bass at the same level? That does sound neither right nor technically feasible and my gut tells me that it would probably be pretty horrible to listen to, with overwhelming +25dB bass drowning out everything else.

Bottom line: what am I not getting here?
 

ernestcarl

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Haven't tried said loudness feature in Equalizer APO, but as mentioned before by pierre -- if you're comfortable with trying out a software solution for a PC -- you can route all audio through JRiver directly first and let it automatically run its own Loudness DSP with just a few clicks:

1590990598053.png


Change the Internal volume reference level to set at what volume level it starts to apply compensation:

1590985679597.png


I've posted the following measurements below before and briefly described it on another thread (here):

1590984173895.jpeg


In my desk's standing position FR measurements (shown above), the compensation starts immediately as soon as I lower the volume below 100%; however, in my sitting position I set it to start when adjusted below 80%. Since I've set the program to always upmix/downmix to 'pseudo' 5.1ch audio, it's really difficult to make a sweep of all channels at the same time without causing some kind of cancellation in the higher frequencies.

Below are averaged RTA measurements with psychoacoustic smoothing -- hence the smoothness -- using the MMM (moving microphone method/measurement) of all channels playing at the same time at different volumes in my desk's sitting position:

1590995202778.png

*The slope of the higher frequencies with the averaged RTA measurements is somewhat less steep in reality. Also, I could probably use a few decibels off using a low shelf filter around 500Hz or so -- I'll have to re-evaluate this with longer listening sessions. Spent the entire day listening to various media content, there's not much reason to readjust anything at the moment.

The EQ settings here needed to be, of course, different as the response differs quite a bit while sitting down and it's worse in the sub bass (substantial null between 60-80Hz), and the HF slope actually looks different than if just doing just a regular sine sweep a few dBs less until you get to the lowest volumes (I reduced the HF shelving & don't quite remember what mic calibration I used previously) -- but never mind that. The resulting compensation curves will appear quite similar overall to the sweeps made in the standing desk position. Sorry, I'm currently too lazy to do an averaged RTA for all volume levels. Anyhow, you pretty much can get a picture what's happening with the Loudness DSP.

I ran a series of pink noise quite a while ago to see how well JRiver's Loudness DSP conformed with the ISO 226:2003 standard with volume change and I do think it does a pretty good job here.

1590986864757.png


If you've experienced using a really good Loudness DSP, it's extremely hard to want to go back -- why the hell would you? It makes it enjoyable to listen to music at all volume levels -- most esp. when set low like between 15-40%
 
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Aerith Gainsborough

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Thank you for the measurements.
I did try JRiver, as you suggested.

Interesting experience, the effect is more subtle than the graphs would suggest. I wasn't able to calibrate anything, since I can't measure headphone SPL but the difference was pretty noticeable once I adjusted foobar & JRiver to roughly the same volume (done by ear) and then switched between the two during the same track. JRiver definitely sounds much punchier and lively in the bass department at low levels. W/o proper calibration, I probably had way too much bass in the signal but it's enough for a first impression.

What an intolerable little program though. I had to disable my network interface, because it went berserk and started DLing all of my "online only" videos w/o ever asking. I hate it when applications hijack my system like that. In general I find it to be a bit bloated. Oh well, one more reason to keep eyeballing the ADI-2 DAC, I guess. :D
 
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dasdoing

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So if I am interpreting the curves in the OP correctly, I would need to "boost" the bass (or rather attenuate the other frequencies in order to avoid clipping) to around 75dB when the midrange is at 50dB in order to perceive the bass at the same level?

no
here are the curves realted to a flat 83dB level, which is our starting point https://www.audiosciencereview.com/...eakers-adapt-to-this.10949/page-3#post-412846


@Pluto I think I just have to trust my own ears on this one. -20dB (after calibrating loudness to 0dB) sounds very bad without the curves for me. -10dB is still enjoyable though, but still get's better compensated
 

Pluto

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I think I just have to trust my own ears on this one
Absolutely – there's really nothing to gain from all this calibration nonsense. All these people that, for some reason, believe that their enjoyment of the content will somehow be enhanced by listening at the ‘right’ level are deluding themselves.

In practice the equal loudness contours are merely an average that's been arrived at after a lot of studies. There is no guarantee that those curves are an accurate representation of your particular hearing or mine, therefore to allow those curves to predicate your listening conditions is a farce.
 

Aerith Gainsborough

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Thought as much.
I mostly had an interest in calibrations because I am curious how it would sound at the "correct" level, since I've never experienced it.
 

dasdoing

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In practice the equal loudness contours are merely an average that's been arrived at after a lot of studies. There is no guarantee that those curves are an accurate representation of your particular hearing or mine, therefore to allow those curves to predicate your listening conditions is a farce.

for me an aproximation is better then nothing. I don't use fixed levels (since no two albuns are equal loudness anyways). I throw in a loudness correction curve for -10dB for example and adjust the volume until it sounds right. And FOR ME it will sound "righter" then without it
 

ernestcarl

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Thank you for the measurements.
I did try JRiver, as you suggested.

Interesting experience, the effect is more subtle than the graphs would suggest. I wasn't able to calibrate anything, since I can't measure headphone SPL but the difference was pretty noticeable once I adjusted foobar & JRiver to roughly the same volume (done by ear) and then switched between the two during the same track. JRiver definitely sounds much punchier and lively in the bass department at low levels. W/o proper calibration, I probably had way too much bass in the signal but it's enough for a first impression.

What an intolerable little program though. I had to disable my network interface, because it went berserk and started DLing all of my "online only" videos w/o ever asking. I hate it when applications hijack my system like that. In general I find it to be a bit bloated. Oh well, one more reason to keep eyeballing the ADI-2 DAC, I guess. :D

Honestly, it took me years -- and, lot's & lot's of customization and practice with calibration before I could truly love like JRiver. I don't think I can live without it now, though.
 

Aerith Gainsborough

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Honestly, it took me years -- and, lot's & lot's of customization and practice with calibration before I could truly love like JRiver. I don't think I can live without it now, though.
Hmm without the ability to measure headphone SPL, I simply pushed the volume to "this is as far as it is comfortable" and set that as reference level to not be interfered with. Currently 70%. Generally I listen at -20dB from set reference volume.

It sounds interesting, though I am not sure yet whether I like that much bass in my music in the long run. Time will tell.

Would be easier with speakers, though when I am listening at low volume here, I generally want less bass because I turn it down to not disturb the neighbors.
 
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