Measurement Bias


Measurement bias is the idea that if you know the measurements of something that information will already bias your perceptions of it’s performance. For instance, knowing the g-force at which car A might slip vs. car B could affect your perception. B, having a higher g-force rating should be a "better" car but if you did not know this you might rate A as better. It may be more fun to drive.

I’ve seen this happen in a review in (I believe) TAS. The review was for a DAC I purchased. The reviewer noted it as "noisy." I read this after I had purchased and been listening to the DAC for a while. I was more than a little shocked, I could hear no noise whatsoever from the DAC. I pulled out an oscilloscope and sure enough, there was unexpected ultrasonic noise on the outputs. I eventually did sell the DAC, but not because it was at all noisy, but because new DACs handled Redbook (44.1kHz/16 bit) tracks so much better. Nowhere in the review did the reviewer mention they had measured it, and they certainly did not point out the deficiencies in Redbook playback, but the reviewer absolutely presented this DAC as noisy but otherwise OK.

So, my point is, that making assessments on the experience that comes from a measurement in audio is tricky business, and if the reviewer is aware of the measurements ahead of time it will absolutely bias them into hearing things which they’d otherwise not, and leave them blind to other real world challenges.

If you want to put together desirability with measurements you need to look at the work Floyd Toole or Bose have done and others in this area and you wont’ find it in a frequency response chart. Of course, Bose’s research is proprietary, but absolutely no one one earth has spent more money on assessing value vs. measurements and manufacturing dollar than Bose.

PS - Please don't argue the quality of Bose speakers here.  I'm not arguing for or against them.  I'm arguing that the research done in tying together desirability and engineering direction is outstanding.  That is all.

erik_squires

@audition__audio

I dont understand the apparent need for validation by measurements. It should simply be enough to like the sound of a component...

That’s exactly where I stand. We listen with your ears and brain, so listening is an excellent way to determine what gear you like the sound of. (sort of seems like a "Duh" moment to me! 😉) Manufacturing audio gear is a different story, but choosing what you like the sound of shouldn’t require measurement validation any more than determining that a steak tastes good, or that a sports car looks nice in red.

There is a measurement bias for sure... There exist also a techno cult strong bias...The next religion will be techno-cultism... Those implanted and those Amish...

Guess which one i want to be ? 😊

 

Any measurement bias disappeared very quickly when I got into high end audio fifty years ago. My eyes would flit from watts per channel specs, distortion, etc. and what I heard and that was the end of it. There was virtually no correlation between those and what I heard. Revisions in basic measures have occurred without much change in the relationship. The cost in well reviewed mainstream audiophile produces (within variation on taste) has been a near perfect correlation… particularly when throwing in weight in comparison to most metrics.