IM Distortion, Speakers and the Death of Science


One topic that often comes up is perception vs. measurements.

"If you can't measure it with common, existing measurements it isn't real."

This idea is and always will be flawed. Mind you, maybe what you perceive is not worth $1, but this is not how science works. I'm reminded of how many doctors and scientists fought against modernizing polio interventions, and how only recently did the treatment for stomach ulcers change radically due to the curiosity of a pair of forensic scientists.

Perception precedes measurement.  In between perception and measurement is (always) transference to visual data.  Lets take an example.

You are working on phone technology shortly after Bell invents the telephone. You hear one type of transducer sounds better than another.  Why is that?  Well, you have to figure out some way to see it (literally), via a scope, a charting pen, something that tells you in an objective way why they are different, that allows you to set a standard or goal and move towards it.

This person probably did not set out to measure all possible things. Maybe the first thing they decide to measure is distortion, or perhaps frequency response. After visualizing the raw data the scientist then has to decide what the units are, and how to express differences. Lets say it is distortion. In theory, there could have been a lot of different ways to measure distortion.  Such as Vrms - Vrms (expected) /Hz. Depending on the engineer's need at the time, that might have been a perfectly valid way to measure the output.

But here's the issue. This may work for this engineer solving this time, and we may even add it to the cannon of common measurements, but we are by no means done.

So, when exactly are we done?? At 1? 2? 5?  30?  The answer is we are not.  There are several common measurements for speakers for instance which I believe should be done more by reviewers:

- Compression
- Intermodulation ( IM ) Distortion
- Distortion

and yet, we do not. IM distortion is kind of interesting because I had heard about it before from M&K's literature, but it reappeared for me in the blog of Roger Russel ( http://www.roger-russell.com ) formerly from McIntosh. I can't find the blog post, but apparently they used IM distortion measurements to compare the audibility of woofer changes quite successfully.

Here's a great example of a new measurement being used and attributed to a sonic characteristic. Imagine the before and after.  Before using IM, maybe only distortion would have been used. They were of course measuring impedance and frequency response, and simple harmonic distortion, but Roger and his partner could hear something different not expressed in these measurements, so, they invent the use of it here. That invention is, in my mind, actual audio science.

The opposite of science would have been to say "frequency, impedance, and distortion" are the 3 characteristics which are audible, forever. Nelson pass working with the distortion profile, comparing the audible results and saying "this is an important feature" is also science. He's throwing out the normal distortion ratings and creating a whole new set of target behavior based on his experiments.  Given the market acceptance of his very expensive products I'd say he's been damn good at this.

What is my point to all of this?  Measurements in the consumer literature have become complacent. We've become far too willing to accept the limits of measurements from the 1980's and fail to develop new standard ways of testing. As a result of this we have devolved into camps who say that 1980's measures are all we need, those who eschew measurements and very little being done to show us new ways of looking at complex behaviors. Some areas where I believe measurements should be improved:

  • The effects of vibration on ss equipment
  • Capacitor technology
  • Interaction of linear amps with cables and speaker impedance.

We have become far too happy with this stale condition, and, for the consumers, science is dead.
erik_squires
You are applying the "audio complexity fallacy". You are taking the very high complexity of a 3d, time variant sound field coupled with the high complexity of human hearing and human preference and applying that to simple things in the audio chain.
You judge too swiftly, I only said that the ultimate judge is the ears.... The eye must read the results of measurements and the ears must decide and work to correlate his experience with numbers and curves to improve measures in a increased ongoing experiments....
I want some audiophile engineers measure more and more and always better.... Who is the fool who dont want that?

Perhaps you suffer of the "Engineer fallacy" saying that numbers and curves are all that exist ? This reduce simply to the maps and territory fallacy or confusion...


« Behind the cloud of numbers are ideas» Husserl


I am sure that you dont like philosopher then I will make a citation by a great statistician:


« The numbers are where the scientific discussion should start, not end » Steven Goodman

Steven N. Goodman is an American Professor of Medicine and of Health Research and Policy (Epidemiology) at Stanford School of Medicine.[1] He has extensively contributed to statistics and probability analysis within the biosciences, and in 1999 he coined the term "p-value fallacy".[2]

I can assure you that the " p-fallacy" in statistics is more interesting to read about than your homemade " audio complexity fallacy" that is only a game for audiophile thread forums ...

Concocted "fallacy" and real one are not the same....You have now a real one to ponder about....
Post removed 
I dont understand your point.... the ears-brain create the sound in some particular room...This is truism evident for all...

«A computer can detect tones that are 1/1000 of an octave apart with ease, even 10 times that. The ear/brain, not even close.»

This is a fallacy....

Using a measured number precision in one dimension parameter against the many parameters complexities of the ears-brain, and saying that the ears is less able to resolve information linked to sound...
But that simple signal in the audio chain before it becomes sound .... it is simple, and to assign the complexity of "sound" and "human hearing", and "human interpretation" to a simple electrical signal .... well that is the "audio complexity fallacy", and it is a fallacious argument that has 0 merit.
The simple signal in the audio chain does not become magically a sound, it is the ears-brain that create the sound in a particular room...And i never attributed myself the complexities of the ears-brain to a simple electrical signal...

It is precisely my point, that it is not possible to attribute the complexities of the ears-brain to the electrical signal....A musical sound is create by the ears-brain, in a particular acoustical field, from a particular electrical grid, in a controlled mechanical resonant-vibrating audio system....


Measures systematically implemented are necessary to improve engineered Electrical component....This is good.... But if the engineer is not an audiophile also, who want to buy his design?
A computer can do it 100 times better. A computer can detect tones that are 1/1000 of an octave apart with ease, even 10 times that. The ear/brain, not even close.
We dont need to improve our speakers beyond what humans can hear. 
The brain can detect angle to about 1-2 degrees. A computer can do it 100 times better. A computer can detect tones that are 1/1000 of an octave apart with ease, even 10 times that. The ear/brain, not even close.
That is missing the point.  Sure objectively the computer can do quite many things better and faster than a human mind, but no computer that I know of can interpret musical reproduction the way the ear-brain can.

What you said is the equivalent of saying a computer is "smarter" than a human because it can perform mathematical operations such as addition, subtraction ... millions of times faster than a human brain.  

A computer can perform addition much faster than any person on earth but that does not mean the computer is smarter or even better.