[Rip N' Burn]

Quote:

Originally Posted by Ed Seedhouse /img/forum/go_quote.gif Because it is extremely difficult and expensive to do. And even if the actual sound output by each IEM was identical it wouldn't be once it reached your eardrums, because your ear canals are not identical.

So if you had 2 pairs of the same iem, when the sound reaches your eardrums, would you be able to tell that they don't sound identical?



Quote:

Originally Posted by Ed Seedhouse /img/forum/go_quote.gif The differences are easily measurable and of a magnitude that one would expect to be able to hear. On the other hand the results of "burn-in" (beyond a few seconds) are not measurable. Yet some here expect to hear that difference.

Some do and some don't, yet they have had similar experiences.

Quote:

Originally Posted by Ed Seedhouse /img/forum/go_quote.gif It is only to be expected because people have been told in advance there is a difference and people (including me of course) are very suggestible. It is called "expectation bias".

I had 'expectation bias' with my Triple.Fi's. I read that with 'burn-in' they would sound better, so I expected them to sound better. After the 'burn-in' they sounded the same. My expectation with the IE8 was that it could sound better or sound just the same. They didn't sound the same.

Quote:

Originally Posted by Ed Seedhouse /img/forum/go_quote.gif All I can say to that is that there are so many misconceptions in it I don't have time to cover them all.

The same could be said about your posts.

 

[billybob_jcv]

Quote:

Originally Posted by skeptic /img/forum/go_quote.gif Ed, It seems to me that the core of the disagreement here is in defining what constitutes "useful" evidence of burn-in (or lack thereof). As a general matter, I think we can all agree that naked eye (or in this case, naked ear) observations constitute empirical evidence. For example: even absent a ruler, we should all be able to agree that an ipod mini is smaller than an ipod classic based solely on visual observation. But with respect to listening impressions and the burn in debate, certain questions remain: (1) is the evidence direct/indirect; (2) as qualitative data, is it trustworthy; and (3) what conclusions does the evidence entail (or merely, possibly support?). I will also note that from a legal standpoint, such user testimony undoubtedly constitutes "competent evidence" in the sense that it is descriptive of the personal experience of the witness. Although indirect, I think it would clearly be "relevant" with respect to burn-in. Whether or not it is persuasive is a separate matter. From the above quote, you seem to be indicating that you object to treating even a large sample of user impressions as scientific evidence, based on lack of controls, and I assume, the non-quantifiable nature of the data? Does this mean you reject the scientific value of all qualitative surveys - or do you simply disagree with the conclusion? I think the truth of the matter is that there is some evidence (albeit indirect) on both sides - and there is just a sharp schism as to which evidence we tend to find convincing. You have cited, as "relevant" evidence against burn-in, articles addressing the minimal measurable results of burning in certain speakers. The IE8 burn-in advocates (myself included) reject the value of your evidence because the articles did not test or address the IE8's specifically. (And I would imagine that you concede different transducers could conceivably change at different rates and/or magnitudes over time - although you would deny that these changes, however small, would have any real impact on sound quality.) By contrast, the burn-in crowd believes that their observational evidence is relevant because they/I believe the perceived change in sound likely results from subtle changes in the hardware (rather than in perception of the hardware). Critical to this interpretation of the observational evidence is the fact that most of us who have listened to the IE8's disliked them out of the box, set them aside, and perceived change many hours later. (Akin to eating a familiar dish in a restaurant that tastes different on a subsequent visit.) For me at least, it seems hard to believe that we somehow adjusted to the sound on a subjective level despite the fact that we were not actually acclimating over any duration of time. Rather, the change was perceived after hours and hours of non-listening. So it boils down to a simple judgment call. What is the logical presumption in light of the aforementioned imperfect evidence? Are we allowed to accept a philosophy whereby inductive arguments and indirect evidence have value resulting in an opinion on the matter? Or are we forced to adopt burn-in agnosticism until measurable results confirm or deny a theory?

But doesn't evidence have to be held to a higher standard before it can be declared part of an empirical experiment? Simple observation may be the strict dictionary definition of empirical, but the scientific method requires more than simple observation. Otherwise, one could say there was also significant empirical evidence of UFOs, Bigfoot and the Loch Ness monster.

What I see here is a large set of observations. At least two hypothesis have been put forward to explain the observations. I think the scientific method would then require the two hypothesis to be subjected to critical review, controlled experiments and revision based on new data. Continuing to bring forward more of the same data that could be used to support both hypothesis is interesting, but does not change the status of the two hypotheses - even if it is brought forward by someone who has a strong opinion that only one of the hypothesis is correct. Bringing forward valid, repeatable & verifiable data that supports one, but excludes the other, or that excludes both is what is needed to change the status quo.

I don't know what that data would look like, but IMHO we haven't seen it in this thread.

 

[Ed Seedhouse]

Quote:

Originally Posted by Rip N' Burn /img/forum/go_quote.gif So if you had 2 pairs of the same iem, when the sound reaches your eardrums, would you be able to tell that they don't sound identical?

I don't know. It would depend on the particular IEMs and how much they differ if they do. My not hearing a difference would not mean that no difference existed. In general a decent double blind test on two pairs of IEMs would be very hard to do because the switching time would be long and that reduces the test sensitifity quite a lot.

The simplest way to demonstrate a "burn-in" effect would be to do controlled measurements on a random sample of units both before and after "burn in", and analyse the results according to normal statistical procedures.

Once again I will point out that I cannot "prove" that burn in doesn't exist. I merely believe on the evidence that I have seen that it is highly likely that it does not exist. The original question was if we believe that the IE8 "burns in" I believed it doesn't and still do, because no one has shown me any credible evidence that it does. It is possible, but in my judgement unlikely, that I am wrong. I am willing to change my mind about it if sufficiently strong evidence is provided.

 

[average_joe]

OK, here is an article that shows differences in speakers pre and post burn in!

Quote from the article:
Quote:

Conclusion In an electrodynamic driver featuring the usual surround-diaphragm-spider construction, driver suspension mechanical compliance plays a key roll in determining the measured value of various driver parameters. All of these parameters will shift as the mechanical compliance of the driver's suspension shifts in value. The bulk of a driver's compliance shift will occur at the time of initial burn in.

So, how would IEMs (specifically the IE8) compare to the speakers tested in this article? What materials are the IE8 drivers made from, and what are the specific material properties? How does the ear perceive the small changes measured in this article, if at all?

Is there a way to measure things such as detail, transparency, soundstage width, etc. which are all audible, but to my knowledge don't show up on a frequency graph, impedance chart, or oscilloscope?

While not my specialty, I have worked with material and processes experts that can regurgitate and explain articles like this for various materials. From the knowledge I have obtained working with them, I am sure some, if not all drivers will "burn in." I know for a fact all materials will change over time. How do these changes (and what are the changes for any given material) affect sound? There are some pretty complex polymer network structure changes that can take place in high temperature and vibration conditions.

Quote:

Originally Posted by fzaba /img/forum/go_quote.gif My mind "burns-in." I adjust to the sound in the same way that I have adjusted to the accents of two individuals that I work with. I could barely understand a word they were saying until I worked with them long enough. Obviously they have not changed their accent, but it took a while before I could make out their words. IEM fit and seal "burns-in", too. It always takes a number of tries before getting the right fit and seal with new IEMs. Sometimes you push them in too far, not enough, or at an odd angle. Eventually they settle and you are able to whip them in and out of your ears. For me, this affects the sound more than my mind burning in. And finally, there are times that I listen to music and it sounds crappy, then I listen another day and it's great. Mood has a lot to do with it. Not to mention that small changes in volume will skew perception as well. To those making comparisons with differing volume levels, your tests are greatly flawed. The mind is easily tricked, that's for sure.

I think you have excellent points and I agree with all 3, but only a little with the accent point (How do you truly know their accent didn't change? One of my friends from high school has a greatly reduced accent from speaking primarily English for so many years and acclimating to the language, something I can prove from watching old videos).

I know materials change, and from my listening, those changes do affect sound, even when taking into account your points. I do believe speakers/headphones/IEMs/the IE8 needs burn in, but your brain also does adjust.

 

[thwood3]

My hunch is that there probably is some amount of burn-in possible due to the mechanical properties of speaker cone suspension. But as with everything that happens to us our expectations and theoretical biases will also produce effects we experience as real and legitimate and seemingly independent of our interpretations.

The only way to really tease these two effects apart is through rigorous double-blind experiments. This would be extremely costly but the 'noise' or sampling error involved in the different units w/ different ears and ear canals, etc. could all be averaged out with a high enough n. Of course this would be very expensive. You'd have to have, say, 30 new and 30 burned in pairs of IE8s. But if the experiment was done w/ JVC marshmallows that wouldn't be so expensive...

Until someone does such an experiment all this armchair arguing is just a lot of hot air.

 

[fzaba]

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Originally Posted by average_joe /img/forum/go_quote.gif I think you have excellent points and I agree with all 3, but only a little with the accent point (How do you truly know their accent didn't change?

Thank you sir... but these particular individuals are grown adults that have been state-side for more than 20 years. One from France and one from Nigeria. I doubt their accent would continue changing after such a long time. Same thing with IEMs after hours of playback.

 

[average_joe]

Quote:

Originally Posted by fzaba /img/forum/go_quote.gif Thank you sir... but these particular individuals are grown adults that have been state-side for more than 20 years. One from France and one from Nigeria. I doubt their accent would continue changing after such a long time. Same thing with IEMs after hours of playback.

You doubt their accent would change, while not probable, possible.

And your same thing with IEMs, did you ignore the material property changes or just don't believe that materials can change? And there have been measurements proving changes.

 

[davidhunternyc]

Wow, what a great and interesting thread. I just discovered it, but moments before, I just posted the following on another thread:

"I agree that 100 hours of burn-in is not nearly enough. It is crazy, but even at 300 hours of burn-in, it still wasn't enough time. Since the IE8 is my only IEM, I was shocked to find out that after 500+ hours with them, I noticed that I was turning "down" the volume on my iPod. I could only attribute this to the IE8's ability to open up and relax, even after all of these hours of usage."

Though I strongly believe this to be true, my experience may not stand up to a scientifically controlled study. Until then, we only have out empirical data to rely on. I would be surprised to find out though that my experience is inaccurate. For now, I will stand by my statement. I strongly believe it to be true.

 

[fzaba]

Quote:

Originally Posted by average_joe /img/forum/go_quote.gif You doubt their accent would change, while not probable, possible. And your same thing with IEMs, did you ignore the material property changes or just don't believe that materials can change? And there have been measurements proving changes.

Yes, possible, but highly unlikely. I was looking at the situation realistically; 20 years is a very long time.

I am not refuting the information from the link you posted, but my statement is in reference to HOURS and HOURS of burn-in... I can't see how the sound signature would continually change, much less improve, over time.

 

[billybob_jcv]

You're right, it makes no sense that 300 hours is not enough, but 500 hours was enough. I would really like to see the materials science that would support this behavior. How is that possible? The materials do not understand time, they respond only to the number of cycles, temperature, magnitude of the movement, etc. This is my sticking point on the burn-in issue - I don't disagree that materials change, but I don't understand the idea of it taking hundreds and hundreds of hours.

 

[average_joe]

Quote:

Originally Posted by fzaba /img/forum/go_quote.gif Yes, possible, but highly unlikely. I was looking at the situation realistically; 20 years is a very long time. I am not refuting the information from the link you posted, but my statement is in reference to HOURS and HOURS of burn-in... I can't see how the sound signature would continually change, much less improve, over time.

OK, so how long did it take for you to be able to understand them? I have experienced a specific sound I could reproduce by A/Bing them at one point in time (well, a few close together points), burned them in for say 4 days, then did the same A/B comparison and got different results. How is that possible? No exposure to the burning in IEM.

Quote:

Originally Posted by billybob_jcv /img/forum/go_quote.gif You're right, it makes no sense that 300 hours is not enough, but 500 hours was enough. I would really like to see the materials science that would support this behavior. How is that possible? The materials do not understand time, they respond only to the number of cycles, temperature, magnitude of the movement, etc. This is my sticking point on the burn-in issue - I don't disagree that materials change, but I don't understand the idea of it taking hundreds and hundreds of hours.

I don't understand it exactly either, just saying it is possible with what I have seen/heard. Materials are like a lot of other things, there are a lot of forces at work that are still not understood. But I also understand KISS, which goes against this and it would make sense for changes not to occur.

The most dramatic changes happened int he first 210 or so hours and after that it was just refinement.

Maybe we need a public poll for IE8 owners asking who experienced changes in burn in, and approximately how many hours.

 

[billybob_jcv]

A public poll is interesting, but does not provide data that can be used to prove or disprove the hypothesis. As I said earlier...
http://www.head-fi.org/forums/f103/h...ml#post5871969

 

[billybob_jcv]

Odd - Double post...

 

[Ed Seedhouse]

Quote:

Originally Posted by average_joe /img/forum/go_quote.gif OK, here is an article that shows differences in speakers pre and post burn in!

But the "burn-in" shown is the well known and undisputed "burn-in" that occurs in the first few seconds with a dynamic driver. This is measurable but makes almost no difference to the sound. The article from which you quote concludes that there is, on the other hand, no evidence for any long term "burn-in" effect that significantly alters (let alone improves) the sound.

This is an example of the trouble we can get in when we use sloppy terminology. The "burn in" effects that are the subject of the thread is supposed to be a long term effect, not a short term one.

That dynamic drivers do change their paramaters in the first few seconds of use is not in dispute and in my opinion is not what the thread is really about. That it exists (as it does) says nothing whatsoever about the long term multi hour or multi day "burn in" effects that many believe in and which seems to me to be the real topic here.

 

[FYJX]

Can we not just conclude that some hears the difference and some don't, and some think it's just yourself instead of the Earphone and while some thinks it's the earphone and not your head fooling you. I myself believe that it's the earphones, as some dynamic driver IEM's sound better and better after time. If you said you might have just gotten used to them, sure i'll agree to part of that but i don't think that "getting used to them" is a reason after thousands of hours. Honestly, does one really take hundreds of days to get used to an earphone?