Reverse of the old Loudness Control

[bentoronto]

Originally Posted by Don Hills

Who is Ellie the Greek?
The proof, or otherwise, will be in the spice simulation.

Any talk of proof by simulation gives the empiricist in me the willies.

Sorry, I hoped my "hint" would be enough explanation. The fallacy is supposing you need to correct for human hearing "deficiencies." Human hearing is what it is.... hope this isn't too mysterious a sentence.

El Greco fallacy

With 50 years of studying perception behind me, I still am confused about this loudness compensation thing. For sure, the discussion treads dangerously close to the El Greco fallacy quite often.

[Don Hills]

Originally Posted by bentoronto

Any talk of proof by simulation gives the empiricist in me the willies.

My comment was merely that a simulation will show how accurately the suggested circuit will provide a classic "loudness compensation" curve. If it provides a similar curve to my originally suggested circuit then it will be a preferable solution, as it requires only a 2-unit (for stereo) potentiometer instead of a 6-unit monster.

Originally Posted by bentoronto

Sorry, I hoped my "hint" would be enough explanation. The fallacy is supposing you need to correct for human hearing "deficiencies." Human hearing is what it is.... hope this isn't too mysterious a sentence.

El Greco fallacy

With 50 years of studying perception behind me, I still am confused about this loudness compensation thing. For sure, the discussion treads dangerously close to the El Greco fallacy quite often.

I don't see it as a fallacy. It is a physical fact. The effect is real and quantifiable. Anyone can hear it for themselves. Where we differ is that you believe the "loudness" effect, as actualised by use of the volume control, is natural and does not require compensation, whereas I see it as an unnatural alteration of the music which requires compensation. (Unnatural = does not occur in nature. If it did, there would be no need for compensation.)

In my opinion, music is best listened to at the SPL at the listener position that it was created for. (Creation may mean the original performance, or the engineer's creation of a mix of separate components recorded at different times in different acoustics - or no acoustic at all in many cases.) If we normally listened at this SPL, there would be no need for any loudness compensation. But we do like to listen at different levels for several good reasons, and when we do so we no longer hear the intended tonal balance. Many of us like to adjust the tonal balance at our chosen listening level so that it is similar to the perceived tonal balance at the "correct" level. Done properly, we find this adjustment effective and pleasing. It is an effective mitigation of the degradation forced by having to listen at a different level to that which the work was intended for.

So regarding the "El Greco" effect, I have no problem listening to music that is "tall and thin", provided the music was intended to be heard that way. I imagine El Greco would not be happy if the aspect ratio of his work changed from "tall and thin" to "short and fat" as the viewer moved away from it. He intended it to be seen at a specific aspect ratio, regardless of the distance from it. It's not an exact parallel to the acoustic case, but I hope you see what I mean.

[bentoronto]

Hold on a minute. My original comment was to somebody else's post and also not about doubting the reality of the lab tests which produced the equal loudness curves.

Further, my comment about simulations was not to doubt whether or not a computer could duplicate the theoretical performance of a physical circuit, but whether you could demonstrate some truth about human hearing that way.

Specifically, the original post pointed out that people hear poorly in the treble and maybe should get some EQ correction for it. I pointed out people hear barely at all above 20kHz but it would be fallacious to "correct" for that human limitation... an obvious, self-evident, and intuitively-grasped strange idea. And THAT is an El Greco fallacy.

[Don Hills]

You're right on your first point. I misunderstood your post #79, for which I apologise.

I also misread your point about the simulation - I thought you were doubting that the presented circuit would work as advertised. Again, I apologise.

But on your third point, the original post (#78) didn't specifically single out high frequencies as requiring correction, even though the equal-loudness curves suggest that some HF boost may be useful as the volume is reduced. (Personally, I don't see the need for it. I'll explain later.)

You said earlier, "...The fallacy is supposing you need to correct for human hearing "deficiencies." Human hearing is what it is...."

You're right, but this does not negate the argument for "loudness compensation".

In the specific case of loudness compensation, we aren't correcting for human hearing deficiencies. We're compensating for deficiencies in the reproduction environment.

In a "live" situation, if we move away from the source we experience an overall level decrease. In addition, the treble decreases somewhat faster than the midrange, and the bass somewhat less. We perceive this as a natural tonal balance change, which needs no correction.

In a reproduction scenario, if we reduce the volume by a similar level, the tonal balance does not change. Compared to a distance increase, we have too much treble and not enough bass. We perceive this as unnatural. This is why I believe in leaving the HF compensation alone and just boosting the bass. The natural change in HF sensitivity of the ears, as illustrated by the "loudness curves", takes care of the required additional HF attenuation, so only the bass requires compensation. Which is where we came in, at the beginning of this thread.