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 cd318

audiokinesis

"If we are going to use "distortion" as a metric of merit, we should process our measurements in such a way that the result correlates well with human perception."


In other words more precise and appropriate data - not less.

Remember what the OP said?

"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." 

The idiotic Hi-Fi press is a laughing stock nowadays. Just check out any car magazine and you will see reams of data pouring off the pages. Everything from cabin and tyre noise to the usual 0-60, fuel consumption, BHP/torque graphs etc.

Why is the audio consumer treated with such comparable contempt?
ivan_nosnibor

"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."


Nailed it!

The entire industry currently runs on implicit advertising and marketing. It discovered decades ago that honesty and openness have little or no relationship to commercial success.

There are no longer any actual claims of sonic superiority in any audio product now being marketed. 

None whatsoever. Think about that.

And more to the point, why should they bother when we golden-eared consumers can't even agree whether we want more data, or even which data we particularly want?

Children in the world of adults.








Yes, it’s fair to say that for the majority of consumers science may as well be dead.

Marketing has long abandoned the use of scientific data when attempting consumers to part with their money.

The world has changed and so has the consumer.

Today’s consumers often simply don’t have the time (or energy) to research purchases the way Steve Jobs once did when spending two weeks looking at washing machine performance data before actually buying one.

Audiophiles are no ordinary consumers, but even they will find scientific data in very limited supply - but not snake oil propaganda, not inference, not hearsay, not suggestion etc.

Even the entire world of audio journalism at times seems to be no more than an advertising arm of the well heeled parts of the industry!

When it comes to the exchange of money, for many, there are very few rules and even fewer principles. Sellers are sometimes in a live or die struggle and very few, it seems, are immune to bending the rules a little.

Or even a lot.

Sure the punch drunk consumer might have some legal recourse but it still requires time and energy they might not have.

Into this void steps forward Amazon and before long the whole world is in its sights.

How about high end audio next, Mr Bezos?






mahgister,

Technology and audio have gone hand in hand ever since reproduction of sound became possible. In fact mankind had to wait eons until technology had advanced sufficiently for the recording and reproduction of sound to become possible.

AI, quantum computing etc are knocking on our door and will shortly change every facet of life as we know it. If you thought the internet was revolutionary, you’ve seen nothing yet.

I’m not saying that there is no room for a little romance (or sentiment, nostalgia, love and respect) in your outlook but the march of science is one of mankind’s most valuable reference points.

Let’s not confuse feelings with facts as far as is humanly possible. Facts don’t care about our feelings as this current epidemic is demonstrating daily. No amount of philosophical squirming can change that.

Facts don’t care about that either.

millercarbon, 

AI, quantum computing etc are knocking on our door and will shortly change every facet of life as we know it.

Which shows just how far they have to go. Stupid robot can't even see we have a doorbell.



I have the same problem with certain visitors and delivery folk.

These doorbells can be tricky blighters!