Basically a dynamic driver is a diaphram that is held in suspension. While doing it's job (producing sound) it is moving back and forth thousands of times per second, and with lower frequencies (dozens to hundreds of times per second) the movement is more exaggerated. The material that acts as a spring to hold the diaphram in place is getting flexed during the movement. I cannot possibly see how that material could keep from undergoing some sort of change over the life of the driver.
Now with that change, the way the driver reacts to it's electrical signal must also change. The interaction of the electrical signal and the moving parts is what we perceive as sound. So if one part of that interaction changes, it makes sense that the result will be affected, and the sound we hear will change, if only a small bit.

ClieOS: I understand your point, but my question remains: has there ever been a scientific test on at least one set of earphones? If there has been, then the result would be one step further forward than we are now. If it did prove burn in, then we would be able to say with certainty that that set of earphones was burnt in, and that the phenonomen could be said to exist in at least one instance. As far as I know, we can't say even that yet.

In your shoe example, I wouldn't say the word 'better' was relevant. 'Better' is subjective. What I'm looking for are cold, hard provable facts.

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Thank you. That's the sort of information I am looking for. Based on what you've said, it would seem logical that there would be physical changes. So - has anyone ever measured them?

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I haven't heard this before. Perhaps they do also go through burn-in.
And technically you're right, all phones will continue to change their sound throughout their practical life. However, these changes are not perceptive to the average human.

Perhaps there are a few gifted people that can perceive them. But even for them, such changes probably wouldn't completely change their perception of the phone. If one's perception changes entirely (as is often claimed in burn-in threads), such changes are probably psychological.

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In some instances this is true. But it seems like it would be rather simple to test this question. I mean, all you would do is test for changes in the transducer's response and then see such changes should be perceivable by humans.

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AFAIK, Etymotic, Shure and Westone have (somewhat) officially denied any burn-in in their IEM (I know Ety had done test on their ER4). Sennheiser PR is even better at this :They think their headphone sound great right out of the box and don't think it is necessary to burn-in, if it ever existed

Also, you might want to know that some headphone makers 'run-in' their headphone as a standard procedure to assure the quality / workmanship. So in some case, the headphone has been 'burn-in' before you even open the box.

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Interesting. If the manufacturers deny it happens, then what makes all these users know differently? Unless, of course, they are experiencing psychological adjustments to the sounds as they get used to the IEMs - which I do think could be probable.

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The thing is, you need to quantify how much change is 'significant' enough to count / discount as burn-in (and who to say how much is enough?). The question is simple if there is no change at all during the test, but you still need to account for all possibility, and if you test enough number of the same model of headphone, you will notice change as part of the norm. Then you will need to determine what is norm and what is 'burn-in'.

One of the issue is, beside the user, who would want to do such a test which can very well piss off the manufacturers? It is one thing to say a headphone benefits from burn-in, but it is another way to say manufacturer ships unfinished / underdeveloped products to customer. It will be better off for most commercial site to stay clear on issue like this in the long run, that's why most of them only do their measurement after a certain time of usage, assuming there will always be burn-in.

Eh, don't worry about it.

Science or not, the "burn in" discussed here is largely ritual, superstition, ceremony, etc. etc.

Just listen and let whatever happens happen. Anything else is a waste of time and effort.

Burn-in has its various believers and non-believers. However, I also toss out the following definition of "burn-in," which I do not mean to exclude other possible definitions:

The phenomenon through which a component at first disliked begins to sound much better over time (often measured in hundreds of hours) and correspondingly more like the majority of posted impressions about said component.

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heehee

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I agree that burn-in does occur. However, there is no evidence that it is perceptible to humans.

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I like your definition.

I don't believe in burn in. I do believe in adjusting to a different sound and liking it more after 100 hours though. But burn in is sort of a ridiculous concept to me. The reason we adjust to shoes is because the material bends when you walk, instead of it being stiff when it's brand new. But earphones don't bend and we dont change anything while it's being worn. So when people say the burn in concept is similar to adjusting to shoes, I just don't think that analogy is valid. Like people have said in this post, nothing really changes. Burn in is not real! But I do like how headphones sound after listening to them for 100+ hours because i adjust to the sound. So burn in, to me, is a psychological concept.

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One way they made proof of the practical use of the vitamin C was to take two groups of lab rats and gave one set food and water. The other set food, water and vitamin C. They then put small cuts on there back and after they were dead suspended weights from their skin. The rats with scar tissue better built up from vitamin C could hold more weight.

There could easy be tests which show a major change in the headphone material. A change do to use would show the effects of burn/break in.

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It is the concept that the mechanical parts of transducer, such as the diaphragm (which is usually some kind of plastic or polymer in general), can be in a more 'relax' state after a certain usage under vibration, like how wearing new shoe for a while relaxes / breaks in the leather / plastic of the shoe.

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I'm sure tests would show a change at some level. However, this change, from a scientific perspective, would not be perceptible by humans.

"Believers" will say that science doesn't account for "golden ears." However, believers will also reject the results of double-blind tests. In any case, there is no objective evidence that currently supports the existence of burn-in.

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Again, such change does occur. But there is no evidence humans can perceive it.