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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

Showing 5 responses by ivan_nosnibor

ivan_nosnibor's avatar
ivan_nosnibor
1,055 posts
 
Erik, I don’t think it is so much the death of science that has stopped the adoption of better measurement methods so much as it has been the rise of marketing. Not just the sheer amounts of advertising, but journalism and also the advent of the internet of plenty have conspired to distract us (the consumers) from the notion or concept of what a relevant set of measurements might look like or the significance of its role. In the 80’s the entire hobby was accessed through b&m stores and magazines. It was a lot easier for most everyone to point to an article now and again that might propose or explore new test techniques, since that put it still within the bounds of usual discussion. But, since then the sheer amount of information that has been made available to us average consumers has mushroomed. Combined with the internet, and suddenly ’everyone is an expert’ in this information glut. And an informed/distracted (from the original idea of a standardizing of test methodology, in this case) public, in that regard, will almost certainly be marketed to differently. Once that notion fell out of public consciousness, then the pressure was off of manufacturers or advertisers to maintain it.

But, dial back the clock on any audio discussion and you might find people talking about at least Some issues that...well, maybe..we might ought to be still talking about even today. Time and innovation march on, but, in our haste to get to the future sometimes, it seems there may not be anyone in charge of making sure that we remember to bring along Everything that might be important...or that might prove to be.

Manufacturers might listen though - IF everyone were telling them the same thing. But, which comes first, the manufacturers talking about the right specs, or the consumers...the chicken or the egg??
ivan_nosnibor's avatar
ivan_nosnibor
1,055 posts
 
It may be a bit slow in coming from me, but I want to clarify a bit of what I already posted a while back. I said:

’I don’t think it is so much the death of science that has stopped the adoption of better measurement methods so much as it has been the rise of marketing. Not just the sheer amounts of advertising, but journalism and also the advent of the internet of plenty have conspired to distract us (the consumers) from the notion or concept of what a relevant set of measurements might look like or the significance of its role.’

’Once that notion fell out of public consciousness, then the pressure was off of manufacturers or advertisers to maintain it.’

When I used the word ’conspired’, I did not actually mean to imply a ’grand conspiracy’ that is always to be considered automatically malevolent toward the consumer and that we are all somehow doomed. It was not my intent to project that as a determining attitude of mine or that it was sufficient grounds in my mind to never trust in manufacturers or in innovation ever again. I’m sure at the least I neglected to say that those things **inadvertently** conspired against us, on that point anyway. Even though I’ve had many occasions in my time to feel as though I couldn’t take manufacturers at their word, that was not my point. What I was trying to illustrate was the **mechanism** in the marketplace by which I believe the pre-existing public awareness of measurements and their role had left us. I know my remarks were seized upon earlier in the worst light (my own fault for not being more clear), but I’d prefer to take a moment and set that straight here. And if because of it I came across as unseemly toward manufacturers here, then I apologize. Anyone that I can believe is attempting to further the causes of both maker and end user alike is, contrary to how it may have looked, is quite welcome here by me.

I believe I welcome innovation as well as the next person. But then again, innovation in the market can be notoriously hard to spot. I’m still in the middle of reading the material...but white papers and I argue a lot...and I lose those arguments more often than not.

But, I remain fixed that my ears will have the final say, whatever the tech is or promises to be. Yet I look forward to progress. In the past, tech innovations have come from other disciplines or fields...like Bybee devices by way of the DOD. It does not surprise me to find this trend continuing, should it pan out.

But, as has already been pointed out, I’m sure Erik is dead on the money for raising the question from the start and I would love to see it answered positively, from whatever quarter that may come.
ivan_nosnibor's avatar
ivan_nosnibor
1,055 posts
 
I have to say, all things considered, it's better to be artificially intelligent than genuinely stoopid. 
ivan_nosnibor's avatar
ivan_nosnibor
1,055 posts
 
Here, belatedly, is a picture-perfect example of the kind of (protracted) misinformation campaign that manufacturers have, and do, engage in.


https://www.youtube.com/watch?v=kPqpuTO6Kd4

If you can watch the whole way through, you can see the story unfold in front of you. Although the video is by no means meant as indictment, per se, of this sort of behavior, you should be able to see why I for one am not automatically willing to accept at face value what any given maker has to say about their product or design. The long, slo-mo dance presented here involves certainly the initial ignorance or misapprehension on the part of the consumer, but also the deliberate manipulation of that ignorance on the part of the manufacturer - even if that can stem, quite understandably, from the maker's unwillingness to surrender technical discussion to their competition. But, this sort of thing is why I do not take, nor ever will take, nor should ever be expected to take, a manufacturer's explanation simply at face value, no matter how respectfully they may present it. This does not mean that all makers are evil and therefore must be burned at the steak, it just bears outs caveat emptor. But, a certain amount of these behavioral motives here are necessarily going to be baked in. 

The harder any manufacturer works at being polished at appearing to make all the above out to be a non-issue, the more suspicious of their ultimate motives I typically become. In general, there can be reasons to doubt such highly polished explanations as well as those that are not nearly trying so hard or certainly even those who offer no explanation or rationale at all. But, the video happens to be an excellent encapsulation of human nature in the marketplace.
ivan_nosnibor's avatar
ivan_nosnibor
1,055 posts
 
@erik_squires  I couldn't follow many of the graphs and such, but I found the summary and discussions pretty intriguing. 

Didn't realize it was known that (dynamic) drivers had that kind of "memory"...(and yet somehow it does not entirely surprise me??...maybe I absorbed something by osmosis over the years somehow [by listening I mean]).

Thanks for the links. I'll need to revisit them going forward and see if I can go a little deeper into it.
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