Burn in - Two Sides

I may be a cynic, but I've always noticed that the headphones with the most "controversial" sound signatures have the longest given burn-in periods.

 

EDIT: Also, if you could control the placebo effect/bias that easily, it wouldn't be a problem.

All I got from that was "I liked colored sound until I got used to neutral sound." No proof of burn-in.

 

Oh this is a rather interesting conversation

To the OP, here is a neat little experiment for you to try:

 

1: Grab an equalizer plugin for your favorite media player... preferably one that allows for detailed adjustment.

2: Put in some standard listening music

3: Listen for a little bit to expose your brain to the sound

4: Alter listening, choose some choice areas of the EQ to change... try to keep it under 6db or so ( don't want to be too overt). 

5: Play back the music, and let it play for a good chunk of time.

6: After said chunk of time, hit a button on the EQ controls to set it to flat. 

 

The result of this should be that after messing with the EQ and listening for a while, your ears become acclimated to the change in freq response, which you can easily tell in this case when you change the EQ back to flat (suddenly everything sounds rather different an uncomfortable). This happens to me when I EQ my headphones for what I perceive to be a neutral freq response; if I change it back to flat with the total output db being the same on both curves, it sounds really messed up and rather hard to listen to. However, that starts to go away after mere minutes of listening, with the affect continuing over time with diminishing returns (sort of like how the eye adapts to darkness: it “boosts the gain” where needed).

 

I think this is indicative of a very basic property of life in its current state: life has developed to a point whereby current species show remarkable adaptation to various living conditions, therefore assisting in their survival growth in numbers. Humans, being the most complex sort of life we know thanks to the size of our brains, have proven to be one of the most adaptable to a multitude of different environments which is shown by our virus like expansion across the planet… however, this regulates our ability to be objective observers of the subtle to be in the realm of very very poor. What ever systems are at work in this process have an inherent leaning towards an equilibrium, ergo, if you change the environment you change what ever is connected to said environment: our body's systems adapt and change to reach an equilibrium.

 

 

Now I know that’s a rather bold claim to make… but trust me (and read for yourself if you don’t) if there is one thing that social psychology, neuroscience, and behavioral science has shown, its that there is a lot working under the hood that we aren’t privy to. The ocular blind spot is a rather easy to understand and definitely provable example of this sort of processing of the senses that serves a purpose not super concerned with objective measurement and recollection of the world, but rather, the purpose is just to keep us away from the lions, and direct us towards the berries. 

 

Regarding break-in: you're correct that everything that has a beginning has an end; everything degrades/changes over time. It's not so much a question of if "burn-in" is real per say, I think it's better looked at as "how much is this driver burning in? and how much is my hearing burning in as well"? Definitely not a simple thing to be sure of... then again, what is when looked at close enough.

Edited by Dr. Strangelove - 9/1/11 at 12:07pm

You have a few pounds of an electrochemical analog signal processor between your ears.

No, you do not have complete, conscious control over it. It does a lot of things on its own that you aren't aware of. Among those, it feeds your expectations and beliefs into your perceptions. It revises memories. It does a lot of stuff no one understands yet. Like the typo I just noticed and corrected while I was sure I hadn't made one.

So when stuff happens that doesn't square with science, it isn't a problem with science. It's usually because the analog hardware in your head is telling you to look at the wrong cause and effect.

If a sugar pill causes someone relief from pain, that doesn't mean you throw out everything known about sugar and start looking for its magical properties. You instead look at how a belief system causes the placebo effect.

And there are lots of beleif systems in audio. There's a rich folklore and loads of superstition. That gets internalized and fed into your experience.

Control for those things and the magical effects go away.

So if you want to demonstrate that burn-in exists, you need to supply hard data. Measurements, of course. You could also disassemble a driver and demonstrate that the physical parts have actually changed.

But if you say that measurements aren't any good that that things change without actually changing, that science is wrong because your perception is different, then the differences are probably imaginary.

There's nothing wrong with folklore and fantasy. It's fun and exciting. But it's better left in literature and movies. Or dressing up in a costume and going to a convention, if that's your thing.

Tyll and I just finished some double blind tests using a pair of new Q701's and a very burned in pair ( 2000+ hours ).  He will post the results soon I am sure.

That should be very interesting. Very few DBTs around with headphones (understandably, especially cross-model!)

Well, technically, they weren't double blind, but they were blind tests, and reasonable well controlled.  

 

They were good enough to determine whether we could hear the differences or not, though.  That's for sure.

 

Post will go up this week.

I've recently made up my mind on how I feel about burn-in:

 

1) It's a physical fenomenon. It happens. You can say in some cases, maybe in most, it's inaudible, but if you ever picked up a physics book you know it happens. The driver is basically a diaphragm stuck to a metal coil. That membrane is moving. As every single material, it wears out, that is, it becomes more flexible. This isn't magic, it's basically the same as it happens with a plastic grocery bag: pick one up completely new and unused, use it to carry stuff everyday and eventually it wrinkles up. Of course your K701's driver isn't going to wrinkle up, and bless you for that, but it has the same effect on a much more microscopic way. This just happens it isn't open for debate; you can however say it happens in unnoticeable ways.

 

2) Your opinion isn't written in stone. Just because you don't experience something, doesn't mean it doesn't exist (this point gets back at me a lot, since I'm an atheist). I once saw a user swearing by everything holy that his Shure never burned-in, and soon enough another user pointed out that Shure did membrane stress on their drivers, so basically they got to the user pre-burned-in. I own Shures too, at first I thought there was some improvement, then I got objective and realized I was probably imagining it (I noticed an increase in detail and better highs, but that has probably more to do with the purchase of an E7). As long as something makes sense, as shown above, the fact that you didn't observe it doesn't disprove it.

 

3) Different headphones have different drivers. I'm sorry for stating the obvious, but sometimes it's needed. Basically what I meant was that if a headphone's driver has twice the membrane thickness as another driver - which would still be really thin, and probably there's such an example - it would take it immensely more time to be considered fully burned-in. Some headphones might change in a week, while others might literally take 6 months. It relates to the tensile strength, which increases with the diaphragm thickness, and so the thicker the membrane, the more work needs to made upon it to reach the same wear-out. A small increase in thickness might mean 10x the burn-in time, which might be a process so slow, owners of said headphone might say it isn't real at all.

 

All in all I'd like to focus on point 1: it happens, regardless of wether you believe in it or not. Of course your own perception of sound might be a lot more effective than months of membrane wear-out, so you get used to the sound before it's burned-in, or basically you just want to believe it changed. And of course the effect of this wear-out might be inaudible. Just don't say a membrane is the same after 10 years of use.

 

Also some people like to say "burn-in doesn't happen because there is placebo herp-derp". Yes, of course there is placebo. I don't think anyone here will deny it. Even I thought I heard my SRH750 better, or that a certain mp3 song sounded worse than in FLAC file (only to later found out that it was the exact same mp3 file, but converted to FLAC. If you give someone an mp3 and a FLAC converted from mp3, most will swear the FLAC sounds better). Placebo exists. But why would that mean that it's an alternative to burn-in, that is, why can't they co-exist? Placebo is a psychological effect, burn-in is a physical, seems normal.

Edited by LizardKing1 - 9/14/11 at 4:26am

Someone posted awhile back with freq. response graphs for the same headphones before/after some burn in, and there were differences. I forget who/when. But whether the differences are audible is the real question, and that hasn't really been tackled yet in a solid experiment.

 

Like the OP said, physical properties change from use. Otherwise every piece of audio gear would last forever.

Well there are some tests about it. If you consider, for example, someone who used a pair of headphones for about a year, they broke, they got a replacement and found out they sounded worse than their old pair. And isn't Tyll supposed to post a non-blind test's result?

Err, finding a new headphone sounds worse means nothing unless it's a blind test and it's confirmed that the headphones sound the same before burn-in. It means less than nothing if the person doesn't even have the two headphones at the same time and has to rely on aural memory.

 

Tyll posted blind test results which showed that there are audible (subtle) differences between a fresh K701 and a burned-in K701, but he didn't control for product variation so it's suggestive and not conclusive. Simply because of the nature of headphones (placement on the head, pad wear) I don't know if there will ever be a conclusive listening test.

I lol'ed at this statement:

"it's confirmed that the headphones sound the same before burn-in."

So you went out, tested ALL the headphones in the world and then wrote this? You can't say something like that. It should be more like "from what I've read on tests online, there doesn't seem to be much of a difference on most models".

 

Also Tyll made a test and the results weren't to your liking, so automatically it was flawed and any sound difference was because of anything else besides burn-in. But if he had said it sounded the same the test would be more conclusive right?