Burn in and peer reviewed brain research

Pig was shot out of a catapult 😂😂🤣

@audphile1 Furutech GTX-D NCF Rhodium -- my Porter Port would be so crestfallen if I found a new, er, outlet. 

1. The article does not conclude that sonic changes during a burn-in period are not a physically "real" phenomenon. It merely finds that, in some cases, psychological factors can influence such perceptions.

2. As the OP predicted, I can state with some certainty, from personal experience, that at least in some instances, the phenomenon is real.  The low-end of my Audeze LCD-X headpones changed dramatically after a week of burn-in.  At first, I thought they might be defective, with so much mid-bass that the lower mid-range of The Beatles’ "Come Together" was barely audible.  After burn-in, the bass was tight and realistic.  I can confidently state that this was not confirmation error -- it was like dialing a tone control from 10 to 3.  In fact, to my surprise, I experienced a similar experience with a pair of LCD-3 phones a few years later.

3. Conclusion?  Like so many other audiophile controversies, the thing to remember is that you can’t prove a negative.  Some can say that they definitely heard a sonic effect, some can say the opposite.  If the question is whether such a sonic effect CAN exist, the former is evidence, the latter is not.

IOW, burn-in is a real thing is some cases.  In others, it may be little more than a psychological illusion.  Case closed.

But come on -- didn’t we already know this?

...and I have to take issue with the OP’s statement: "It found no substantial evidence for mechanical changes producing audible differences."

Yes, the article does state: ":In light of the lack of substantial evidence supporting mechanical changes during burn-in, the onus shifts to human physiology"

This is a conclusory statement.  Cliche time: "absence of evidence is not evidence of absence."  But even if this was not true, the authors do nothing to support this statement. There is NO evidence supporting mechanical changes during burn-in?  I beg to differ, especially when it comes to speaker transducers and certain types of capacitors. A more skillful, more ethical, author might have instead said, "IN INSTANCES IN WHICH there is no evidence of mechanical changes..."

But if you meet someone who argues that the compliance of spiders and surrounds, or the centering and excursion behavior of voice coils, does not change as a mechanical transducer is broken in, you should just walk away.

Here are some published papers supporting my position:

“Measurement of Suspension Parts”
h t t p s://www.klippel.de/fileadmin/_migrated/content_uploads/AN05_Measurement_of_Suspension_Parts_01.pdf

“Large Signal Parameters — Changes Over Time”
h t t p s://www.klippel.de/fileadmin/_migrated/content_uploads/AN17_Changes_of_Loudspeaker_Parameters_01.pdf

“Loudspeaker Driver Nonlinearities — Measurement and Modeling”
h t t p s://www.aes.org/e-lib/browse.cfm?elib=13167

“Changes in Loudspeaker Parameters Due to Aging and Use”
h t t p s://www.aes.org/e-lib/browse.cfm?elib=1605

“Low Frequency Transducer Aging and Parameter Shift”
h t t p s://jblpro.com/en/site_elements/tech-note-low-frequency-transducer-aging

There are many more.

I thus don’t think much of the paper cited by the OP.  Having been through the publication mill myself, it looks to me like little more than an example of an opportunistic author doing a half-assed job to get a quick-and-dirty publication.  Little of the information in that paper could not have been retrieved by an AI bot -- or even a traditional search engine -- and the fact tthe author simply ignore relevant bodies of evidence with a wave of the hand label the piece, in my book, "lazy science."  I’m disappointed that PubMed would have published it.

cundare2 – Good points on the mechanical side — the Klippel papers are legitimate, and you’re right that loudspeaker transducers measurably change with use. The "no substantial evidence for mechanical changes" claim is worth pushing back on. And people in this thread already have. I thought that aspect of the article was settled.

Keep in mind,  that claim is the article’s, not mine. I was summarizing what the authors concluded, not endorsing it. Your quarrel there is with them. As I pointed out fairly early in this thread, I find this type of research interesting and was asking for more. Most on this thread have just taken to beating up on this article, crying "foul," defending their experiences, etc. Ok, well, this is just an audio forum and most people are not interested in searching out more literature. Some are, but most would rather offer their view, or think through the logic or illogic in the original post. 

Coming back to your argument, where I’d push back is in where you take the engineering papers. They establish that mechanical changes occur and are measurable. They don’t establish that those changes fall within the audibility threshold, or that they’re what you were actually responding to in the LCD-X case. That’s a further inference the papers don’t provide. But thanks for citing – I am glad to have the references.

The personal experience example is vivid, but "like dialing a tone control from 10 to 3" is exactly the kind of dramatic, unblinded, cross-session comparison that psychological accommodation explains most parsimoniously. I don’t doubt the experience was real. The question is what it’s evidence of. Strong confidence in the absence of confirmation bias isn’t itself evidence of its absence — that’s rather the point of controlling for it experimentally.

The asymmetry you invoke at the end — positive reports constitute evidence, negative reports don’t — is worth thinking through. If every positive report counts as evidence for burn-in but no negative report can count as evidence against it, then there’s no possible observation that could challenge the claim, which means it isn’t being held to any evidential standard at all. 

The "you can’t prove a negative" move is also slightly off-target: nobody needs to prove burn-in never happens. The question is what standard of evidence we require before accepting that it did happen in a specific case. And under controlled conditions the asymmetry actually runs the other way — a well-controlled negative result (blind, level matched, same session) is more informative than an uncontrolled positive one, precisely because it rules out the competing explanations the positive report leaves open. Unblinded, cross-session personal experience doesn’t clear that bar — not because the experience wasn’t real, but because it’s compatible with too many alternative explanations.

None of this closes the case against burn-in. It just means the case isn’t closed by personal experience either, however compelling it felt in the moment.