Author Topic: How sensitive are our ears? My experiment.  (Read 3146 times)

Offline steve

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How sensitive are our ears? My experiment.
« on: August 11, 2016, 03:44:38 PM »
Been performing this particular experiment over the years. Playing lone cello on mine and another's systems. On the back of my 11A Line Preamplifier I have a control in parallel with my output jacks.

It adjusts the low bass response, at a -6db/octave, but only enough to cover different amplifier input impedances (Z) from 20k ohms on up. The object is to have the same, accurate, bass response with differing amplifier input Z.

It is a simple experiment, as me and whoever else listens, I adjust the bass response until the other notices a sonic difference. We do this a number of times. If I want, I just pretend to adjust the control.

I then use Cirmaker program to measure the amount of FR change at 20hz. Over and over my subjects were able to perceive differences to 32udb (micro db) change at 20hz.

+/- 0,1db difference in frequency response is typical to -54 db changes at 20hz. 32udb is consistent to -95db or lower changes. This is vs normal listening levels. At cello frequencies, it is even lower.
 
With such data, I am not surprised, and supports the perception most have that different components sound different. 

Is this all encompassing? Of course not. Much will depend upon the venue, components, musical selection etc. But I have found that it is possible to perceive to such low levels.

I thought that was quite an interesting type experiment.

Cheers
Steve
« Last Edit: August 11, 2016, 03:56:37 PM by steve »
Steve Sammet (Owner, Electron Eng, SAS Audio Labs, Ret)
SAS "V" 39pf/m 6N copper ICs,
SAS Test Phono Stage
Acutex 320 STR Mov Iron Cart
SAS 11A Perfect Tube Preamp
SAS 25 W Ref Triode/UL Monoblocks
2 way Floor Standing Test Speakers

Offline richidoo

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Re: How sensitive are our ears? My experiment.
« Reply #1 on: August 13, 2016, 08:38:34 AM »
Low Q EQ is pretty easily audible even at LF, but .1dB that's pretty impressive. So much for the psyches saying our LF perception is less sensitive than midrange. There's nothing more exciting and desireable to audiophile than low distortion bass. Everybody loves bass detail, but we can't actually hear it. Uh huh..

I always wondered what that knob on back of 11A was for?  :thumb:

Offline steve

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Re: How sensitive are our ears? My experiment.
« Reply #2 on: August 13, 2016, 08:50:03 PM »
Low Q EQ is pretty easily audible even at LF, but .1dB that's pretty impressive. So much for the psyches saying our LF perception is less sensitive than midrange. There's nothing more exciting and desireable to audiophile than low distortion bass. Everybody loves bass detail, but we can't actually hear it. Uh huh..

I always wondered what that knob on back of 11A was for?  :thumb:

Ah, I gave it away, now you know Rich. :)

I was quite dumbfounded to find how sensitive the ear can be. I find altering the bass and its effects on perception to be an interesting topic to explore.

Cheers
Steve
« Last Edit: August 13, 2016, 08:52:04 PM by steve »
Steve Sammet (Owner, Electron Eng, SAS Audio Labs, Ret)
SAS "V" 39pf/m 6N copper ICs,
SAS Test Phono Stage
Acutex 320 STR Mov Iron Cart
SAS 11A Perfect Tube Preamp
SAS 25 W Ref Triode/UL Monoblocks
2 way Floor Standing Test Speakers

Offline steve

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Re: How sensitive are our ears? My experiment.
« Reply #3 on: January 10, 2017, 10:38:59 AM »
I have been having some friends over, at different times of course, and adjusting the xover on my test speakers.

In my latest experiment covering several months, I have been adjusting a 9k, 9,000 ohms, resistor by less than 0,1 ohms. The 9k ohms is in parallel with a 16 ohm fixed resistor which is in parallel with a full range driver. By doing such, I am altering both the tonal balance across the full range driver, and the relationship between the full range driver and woofer.

We found one can perceive such differences in tonal balance. (This is not the same as spl across the entire audio band.)

To be super cautious, let's use 0,1 ohm rather than hundredths, and let's leave out the full range driver impedance. We will just use the 16 ohm resistor parallel with 9k ohms.

9,000 in parallel with 16 ohms.
A. 15.97160603

9000.1 in parallel with 16 ohms.
B. 15.97160635

Divide B by A and we obtain 1.00000002 .

That is the resistance change just across the 16 ohm resistor when I changed the parallel 9,000 ohm resistor to 9,000.1 ohms.

And we have not included the parallel full range driver impedance (Z), which would make the ratio 1.00000002 substantially less.

The figure represents a tonal balance change of -120db to be on the cautious side. -130-140db is more like it.

I can perform the experiment using either a silver contact switch (10 milli ohms contact resistance) or a variable potentiometer across a very small fixed resistor, in series with a very very large resistor.

There are a couple of important points.

1. The perception is somewhat dependent upon the music played.
I have been using much more variety of music for testing.

2. One has to understand that weighting of harmonics is involved. Olsen's research has found that the higher the harmonic, the more sensitive the "ear" is to changes.
Changes to the 3rd harmonic is more easily perceived than changes to the 2nd harmonic. 10th more than 9th etc.

Cheers

Steve

« Last Edit: January 10, 2017, 10:47:20 AM by steve »
Steve Sammet (Owner, Electron Eng, SAS Audio Labs, Ret)
SAS "V" 39pf/m 6N copper ICs,
SAS Test Phono Stage
Acutex 320 STR Mov Iron Cart
SAS 11A Perfect Tube Preamp
SAS 25 W Ref Triode/UL Monoblocks
2 way Floor Standing Test Speakers

Offline steve

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Re: How sensitive are our ears? My experiment.
« Reply #4 on: January 12, 2017, 10:19:25 AM »
Delete the -130-140db comment above. I meant -120db.

Cheers

Steve
Steve Sammet (Owner, Electron Eng, SAS Audio Labs, Ret)
SAS "V" 39pf/m 6N copper ICs,
SAS Test Phono Stage
Acutex 320 STR Mov Iron Cart
SAS 11A Perfect Tube Preamp
SAS 25 W Ref Triode/UL Monoblocks
2 way Floor Standing Test Speakers