Equal Loudness

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Fletcher-Munson Curves - Wikipedia
"The Fletcher–Munson curves are one of many sets of equal-loudness contours for the human ear."

Merlijn van Veen - equal-loudness
This calculator displays equal-loudness contours in accordance with ISO 226:2003. It allows you to normalize to any contour and see relative differences."

This calculater makes it easy to see the difference between 40 phon which correspence to a silent environment and a louder environment like a concerthal.

Equalizer APO download | SourceForge.net
Equalizer APO is a parametric / graphic equalizer for Windows.

add a graphic equaliser and past this text in it:
GraphicEQ: 20 -5; 25 10; 31.5 14; 40 12.8; 50 11.9; 63 10.9; 80 9.5; 100 8.8; 125 7.7; 160 6.6; 200 5.5; 315 3.4; 400 2.4; 500 2; 630 1.5; 800 0.5; 1000 0; 1250 -1.5; 1600 -2; 2000 1.05; 2500 1.065; 3150 -1.5; 4000 -2; 5000 -2; 6300 -1.5; 8000 0.5; 10000 2.5; 12500 4.5; 20000 14
This will give you a nice loudness contour which corresponse to the difference between perceived loudness at 40 and 70 phon.

You can play with different levels of loudness; but to me this 40-70 level sound pleasant with better realistic bassdrum experience.

For my Orions i thought it better to supress the lowest tones of 20 and 25 hz. Be aware of higher woofer excursions.
 
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listening at low volume the impact of low frequency sounds like bassdrum is not realistic without some boost

somehow we not aware of this even when the difference with real life music should be clear

weird enough our mind does not question this difference
 
i use now a 20 phon difference
 

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I think it's more about getting a realistic balance across the spectrum at lower volumes, so for instance how does our brain interpret something played at a lower than expected volume, does it sound like it's further away, does it sound like it's smaller, does this for some reason make it sound less realistic?
 
I've been using the loudness feature on my ADI-2 DAC FS and love it. I'm using this mainly with TV/movies (new house doesn't suit a surround setup, and I have young kids so volume needs to be kept low in the evening).

https://www.rme-audio.de/download/adi2dac_e.pdf

Basically you set a reference level and bass/treble gain at that point. At 20dB above reference the gain of bass/treble is zero. Bass/treble gain is automatically reduced as you increase volume between reference level and 20dB higher.

All settings are made by ear at this point but the impact on voice intelligibility and bass presence is profound (to me). I can switch the feature on and off via the remote, so it's easy to compare.
 

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Hi,


I have trouble with these curves. On my system, it appears that past 90-95dBC, SPL increases more for medium/high frequencies than others. My listening room is very dead (RT60 = 170ms for a room volume of 100m^3). I have to use a flat frequency with bass shelve +6dB for 80-90dBC playback, but a slope of -6dB in the upper part of the spectrum for 95-100dBC playback.


My perception disagree with isosonic curves, I'd like to know if you feel the same or not ?
 
Most loudness circuits just work wrong. That's because most engineers do not know how to design something like that. I have at least already examined 30 or more circuits. Maybe one has worked halfway (from 70s). The experts from the 70s have died away.
 
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