Should you use Fletcher-Munson loudness compensation?

[dshreter]

I know many are familiar with the Fletcher-Munson or equal loudness curves. In a nutshell:

“The Fletcher Munson Curve contains a set of graphs that show that when you listen to music at a lower volume, mid-range frequencies will be sound more prominent, whereas high and low frequencies will be somewhat suppressed.

However, when the volume is increased, the reverse happens – high and low frequencies become more pronounced while the mid-range frequencies fade into the background.

In other words, the Fletcher Munson Curve demonstrates the average sensitivity of a human ear to audio signals of different frequencies at varying sound levels.”

I have a few questions about what this implies in practice.

Should you compensate for this in your own listening? I’m aware in psychoacoustics the brain naturally compensates for many things, so does fully adjusting for equal loudness compensation at low levels sound wrong or is it more similar to the intended mix? And in reference to music, what level is considered reference that you would compensate in relation to?

Given I tend to listen to music at lower volumes I am a bit lost on what to use as a target response curve for EQing my speakers. I could just do what sounds “best” but a little extra bass always sounds good for a little while so I don’t exactly trust my ears to get it right.

 

[Doodski]

Hmmz... This partially explains why I crank up the PEQ high freq to the top stops and then crank the volume up.

 

[rkbates]

Never measured it to see if it follows Fletcher-Munson exactly, but I've found a continuously variable loudness control very useful. Not very audiophile-like, and the position it ends up on varies from album to album (and day to day).

 

[Doodski]

View attachment 176078
Never measured it to see if it follows Fletcher-Munson exactly, but I've found a continuously variable loudness control very useful. Not very audiophile-like, and the position it ends up on varies from album to album (and day to day).

I love the Yamaha variable loudness control. It's just well done. It can really transform a set of speakers into something else for awhile until the next setting comes down the pipe.

 

[Kijanki]

I used to climb the stage and adjust band's amplifiers during softer pieces, but now I'm getting too old for that

 

[Doodski]

I used to climb the stage and adjust band's amplifiers during softer pieces, but now I'm getting too old for that

You where one of those hard working people scurrying about under the lights performing service en route?

 

[dshreter]

It’s funny that there’s some decent consensus that loudness compensation is important but speakers aren’t built to an implied listening level. Or maybe they are. I don’t have data to back it up, but I suspect people that like high SPL gravitate to flat speakers more than those preferring moderate volumes.

 

[krabapple]

wow no one here has heard of Audyssey's Dynamic EQ or other schemes to implement equal loudness curve compensation for low level audio?

 

[MakeMineVinyl]

I don't bother with loudness compensation on my 2nd system because it doesn't add anything much and sounds false.

 

[dshreter]

wow no one here has heard of Audyssey's Dynamic EQ or other schemes to implement equal loudness curve compensation for low level audio?

I think there is familiarity. Similar features are implemented in a lot of gear - some implementations better than others of course.

I guess my question is if you “should” use it, or if psychoacoustics already compensate for how it is meant to sound at higher or lower volumes.

The effect is profound, but I think very few systems are actually EQed as such. Even Dirac which gets a lot of praise I don’t think it supports a dynamic loudness function.

 

[krabapple]

Yes, you should use it

The equal loudness curve *is * psychoacoustics. Why would you think we somehow 'compensate' for it? It is a measurement of how we actually hear. You not only hear disproportionately less bass , you also perceive it so.

It is why loudness buttons were invented.

 

[dshreter]

Why would you think we somehow 'compensate' for it?

I’ve heard a lot of people state it sounds unnatural to them. Similar to how there’s an expectation of different sound in large vs small rooms, I could believe that equal loudness at lower levels sounds strange - in other words it might sound natural for music to be bass shy if it quiet.

But I don’t know either way which is why I wanted POVs.

 

[levimax]

If I am listening very low at night I turn up the bass and it sounds better to me. If listening way louder than usual I turn the bass down a little and it again sounds better to me. For these adjustment I find tone controls better than equalizers or filters.

 

[rkbates]

Yes, you should use it

The equal loudness curve *is * psychoacoustics. Why would you think we somehow 'compensate' for it? It is a measurement of how we actually hear. You not only hear disproportionately less bass , you also perceive it so.

It is why loudness buttons were invented.

I expect there is a big variation in implementation, however the loudness button on a Denon PMA520-AE is exactly (measured) the same as winding up the bass and treble to the max. The 'button' approach seems pretty rough, and I'm not overly keen on letting software automatically apply compensation. I'm sure my random knob fiddling is far better than expert engineers spending years of research perfecting an software solution

 

[maverickronin]

Loudness compensation is amazing. It would be very hard for me to give up my RME ADI-2 DAC's excellent implementation of it.

 

[abdo123]

Can someone share some layman level article with the necessary knowledge to build a loudness filter?

I typically listen at 75dBSPL = 0dBFS and i'm wondering whether i'm missing out on something.

 

[solderdude]

I made this a while ago.

Most recordings are mixed at average levels between 80 and 85dB (depending on the size of the mixing room and other factors)
I have 'normalized' 80 dB equal loudness contour and then you can see what 'compensation' you would need when you listen to different average levels.
Determining what average level you actually listen to is another matter.

I would say just apply EQ based on the right plot with your average SPL and the 80dB reference. When this sounds better to you and your speakers/headphones are correctly tuned this should work.

It is not by chance that my target curve is matching the 70dB line. I too listen at average levels (active listening) between 70 and 75dB average and well made recordings sound good to me on this target.

 

[levimax]

Can someone share some layman level article with the necessary knowledge to build a loudness filter?

I typically listen at 75dBSPL = 0dBFS and i'm wondering whether i'm missing out on something.

@solderdude has excellent information for building a digital filter. Traditionally a Baxandall analog filter was used i.e. tone controls. See project 7 for how to build one using op amps https://sound-au.com/dwopa2.htm

 

[sarumbear]

View attachment 176066I know many are familiar with the Fletcher-Munson or equal loudness curves. In a nutshell:

“The Fletcher Munson Curve contains a set of graphs that show that when you listen to music at a lower volume, mid-range frequencies will be sound more prominent, whereas high and low frequencies will be somewhat suppressed.

However, when the volume is increased, the reverse happens – high and low frequencies become more pronounced while the mid-range frequencies fade into the background.

In other words, the Fletcher Munson Curve demonstrates the average sensitivity of a human ear to audio signals of different frequencies at varying sound levels.”

I have a few questions about what this implies in practice.

Should you compensate for this in your own listening? I’m aware in psychoacoustics the brain naturally compensates for many things, so does fully adjusting for equal loudness compensation at low levels sound wrong or is it more similar to the intended mix? And in reference to music, what level is considered reference that you would compensate in relation to?

Given I tend to listen to music at lower volumes I am a bit lost on what to use as a target response curve for EQing my speakers. I could just do what sounds “best” but a little extra bass always sounds good for a little while so I don’t exactly trust my ears to get it right.

The question is wrong. It should be should we go back to 60s understanding of music reproduction?

 

[DVDdoug]

Can someone share some layman level article with the necessary knowledge to build a loudness filter?

I has to be built-into the volume control circuit or the volume-control software. A basic loudness compensation circuit doesn't "know" the signal level or the acoustic loudness. It only knows the volume control setting. Variable loudness compensation helps you to adjust for that but it's still "imperfect". With software you can calibrate to the acoustic loudness, to some extent. (But you don't want to adjust dynamically to quiet passages, just for lower than expected listening levels.)

I found this. It's rather simple, just boosting the bass and there's no bypass switch. I think the old analog designs normally used a special volume control pot with an extra tap that could be switched-in. But I've never seen a pot like that available to hobbyists.