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
Getting back to the original subject for just a second the only way I would get really interested in philosophy of science or mathematics is if it could improved the sound
Musical sound waves are more akin to " a language", a temporary living quasi-crystals, than to only a mechanical random phenomena...The sound is like a sensible equation, made visible for the eyes, like the wind on undulating grass... Imagine that like the fixed image of a film, if you put some 3/8 inch resonant bowls, on some critical points on the walls of a room, the pattern of the musical sound waves are now less blurred and present to the ears some clearer image where the waves are more clearly perceived.... I guess Fourier analysis will be useful.... :)

This is my last "tweak" or better said my last way to design the acoustic of my room...The acoustical field being one of the 3 dimensions to embed any audio system.... The fourth one, or the fifth one,( if I counted the active and passive treatment of the acoustical field like 2 dimension), being the information field, but this is and you know that, a little too advanced to be explained here and believed... :)
Unless AI or quantum computing or whatever has some direct or even indirect audio application that I can hear forget about it
By the way tomorrow at low cost any A. I. will make any acoustical linked tweaks superfluous.... Simply by an analysis in real time of my ears particular structure and the structure of my room.... That already exist but in an imperfect and static way.... … :) For the electrical grid analysis and filtering it will be the same... for the monitoring and correction of the working of electronic components also...But I will be dead when this will be affordable....


A.I. is in no way a real intelligence because there is no real soul here, and no love....Even ants society is highly more intelligent than A. I. because ants are our conscious brothers, we are linked to them by a common history on many levels.... There is no link at all between humans and A. I. The link between the creator and his machine will be severed by the auto replicant Artificial intelligence itself in a not distant future....A. I. dont need a breathing living planet also, a pure mass of diverse minerals is what this A.I replicant intelligence need....And the chance to link itself to another A. I. because they exist all on the same level in the physical universe where they are remains of Faustian sorcerers ignorant apprentices....

The experience was tried in the past and this A. I. exist already in myth and in reality in the universe...Von Neumann is the first that think about it and his theoretical possibility and reality at the rise of the designed architecture of modern computer...

I will not speak about the "artificial soul" it is a bit more too wacky for the moment.... :)
When a woofer is moving a distance that makes higher frequencies come from different, moving planes, it changes the frequency, due to the Doppler effect.  This is IM distortion at its max.  
Oh come on, I can easily fix that just by changing my speaker cables? Little things acoustic things on my walls? Cable risers?  NO?  :-)
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.