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
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If you are intentionally modifying the signal that is not engineering that is art, in which case don’t make up characteristics for equipment that are simply not true, not validated, not verified, and reproducible and disappear
Thanks, your answer about spirituality is fair enough...

But when I say that engineering is also " art" I dont say that in the sense of your wording in this extract of your post...I dont say that as if I was speaking about taste or fancy....Or illusion....


Some of the tweaks I use modify the sound in a reproducible way and can give new ideas to an engineer...Some ideas I replicate came even from some engineers... Engineering is not only about measuring, it is also innovating, design is not reducible only to numbers and measure....And dont confuse measuring with reproducible....validation by other human beings also count even if not measurable at the moment....And dont call "not true" what is not measured nor measurable at some point in time but validated tough by many human ears...Do you get my point?


If not, you reduce yourself to less than what you are....

If you are faithfully recreating the signal that is engineering and science. If you are intentionally modifying the signal that is not engineering that is art,

By the way, the frontier between art and science is absolutely not clear cut like you pre supposed it to be....Luckily, because creativity is linked to break artificial frontiers, artificial methods, habits, and false rigid distinction that has no link to a living complex reality in biology and in physical reality also....Art is not synonym for illusion and science synonym of reality....This is for common sense and for philosophy absurdly simplistic view...
If one takes the non-spiritual view then there is nothing about the human brain that cannot be replicated.
That is not true. Can you replicate Beethoven or Einstein? If you’re right, then we probably have a bunch of Einstein running around already.  That is such a simple-minded point of view that I have to scratch my head.

Again, you seem to be confused between things that can objectively replicated vs. things that belong to the conscious mind that cannot be replicated.

If you are faithfully recreating the signal that is engineering and science.
That is not possible even with the current equipment. You can come close but nothing in this world that can replicate the original performance 100%. I mean you can come close but not 100%. Currently you got 24bit/192KHz, SACD, DSD and so on but they all have their own compromises.

You seem to be putting yourself into a corner that you cannot get out of :-)
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