[xnor]

  The article you linked clearly states most MRI scanners use a constant magnetic field which behaves identically to a permanent magnet. These are just permanent electromagnets running huge DC currents through superconductors to produce intense magnetic fields.

Yes, as I said, a constant magnetic field is part of MRI scanners.
Second paragraph:

A radio frequency electromagnetic field is then briefly turned on, causing the protons to alter their magnetization alignment relative to the field. When this field is turned off, the protons return to the original magnetization alignment, and these changes in magnetization alignment cause a changing magnetic flux, which yields a changing voltage in receiver coils to give the signal.

 
 

  The source study for that article has since been removed...I wonder why.

Because they have completely changed their site and their archives don't go back to 2004 anymore.
 
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1241963/

 

[xnor]

  Well, I gathered some real data using laboratory quality equipment.  Or actually in this case, the magnetic sensors on my smart phone.  With 3 phones to measure, some OTE Creative Aurvana, Beyer DT880 and Sennheiser HD570's I got the following results.  The Creatives and Dt880 on the side nearest the ear, and as close as possible generated about 1600 microtesla or 1.6 milli-tesla.  The 570's were only about 600 micro-tesla.  Gentle movement near the sensor could triple this.  This with no signal through the phones, just the static magnetic field. 
 
So should we be worried?  Or does it open up another pathway for altering our perceptions beyond just using drugs?

 
Not sure how accurate those sensors are, but valuable data nevertheless. Thanks!
 
So roughly 1 mT.
Beyer T1 or those planar magnetics are probably a lot stronger.
 
 
The real question remains though: do these static fields have any effect on our brains?
And do the fields change when music is playing?

 

[xnor]

I just checked with an LG G2 an on-ear headphone with a small 30mm driver (PX100 like construction) and with 2cm distance from the driver it registered 1.4 mT.
 
Need some kind of fixture because tiny movements will result in the measured value jumping all over the place.

 

[ferday]

   
Not sure how accurate those sensors are, but valuable data nevertheless. Thanks!
 
So roughly 1 mT.
Beyer T1 or those planar magnetics are probably a lot stronger.
 
 
The real question remains though: do these static fields have any effect on our brains?
And do the fields change when music is playing?

of course they have to
 
despite the coil field for example being much lower, there are field interactions there (and with all the other ambient fields that are in constant flux).  i can only imagine the magnet(s) must move slightly as well since it is a rigid mechanical structure.  wouldn't guess how much the fields are changing, probably not to the measurement ability of a phone, but for sure they are.  interesting how a small movement of the sensor apparently altered the measurement by 3x...
 
i also suspect there is some sort of effect on the brain, maybe something we can't yet measure but being as the brain is an electrical device without any particular shielding, well it has to do something one way or the other doesn't it
 
i found a few papers which i don't currently have access to, but here's one abstract 
Magnetic field variations from the human brain produced by visual stimulation have been observed in a normal laboratory setting with a superconducting quantum interference device and no magnetic shielding of the subject. Previously unknown temporal and spatial features of the field near the scalp are reported.

 

[esldude]

Yeah, don't know how accurate the phones are. But they show right around the ballpark for what the earth's field is supposed to be.  They also manage to be quite good for compass use.  So I would NOT argue my reading of 1500 micro tesla vs someone else's 1555 reading.  But I doubt they are off by say 50%. 
 
I did try with and without music.  No difference. 
 
Now pulsing small movement, like you might get wearing a set jogging, can triple readings. 
 
edited because I left out the NOT in the above sentence.

 

[xnor]

  Yeah, don't know how accurate the phones are. But they show right around the ballpark for what the earth's field is supposed to be. 

That's indeed a nice way to check accuracy. My phone is off by only about 2 μT. (46 - 50 μT and according to wikipedia the magnet field here should be about 48 μT).
 
The problem is that with headphones nearby, the measured value fluctuates by a couple of μT over a few seconds regardless of music, and that the sensor wouldn't be fast enough anyway to detect changes at the rate of several (hundred) Hz.
I've tried playing-stopping-playing.. music, but the fluctuations are so unpredictable that they mask the changes I'm trying to measure.
 
 
Btw, the brain produces an extremely weak magnetic field itself: 100 fT to 1 pT.

 

[wolfz]

I measured the EMFs of some headphones with a TRIEFIELD  METER ( 100XE ).
 
Sennheiser  HD600 / 650 , Beyer DT880 , Grado SR 325 , Alessandro Pro , Ultrasone Edition8 & Signature Pro.
 
They all ,apart from Ultrasones, are between 2 - 8 mG with short time peaks up to 15 mG. Of course higher volume higher emfs....
 
Measured at medium volume levels.
 
There is no fixed average value because the needle is constantly changing according to volume and kind of music/ instruments.
 
The Ultrasone headphones have a substantially lower field because of their shielding ( around 80% less).
 
  Measurements at 1cm distance from the headphone pad surface are app 50% lower.
 
This is probably the emf value the outer brain is exposed to.
 
In case I get a HiFiman 560 planars I will post the values. 
 
The " safety limit " is 2-3 mG.   (  1 mGauss  =  0.1 micro Tesla )

 

[Strangelove424]

Does anybody have information on magnetic fields' effects to neurotransmitters or synapses? Xnor's initial comments on emotional effects have me most intrigued, and I believe that's where neurotransmitters would come into play. And now I'm a little curious what the effect is on synapses already formed in the brain.   
 
Edit: I found this, but its not the complete article... 
 
http://www.ncbi.nlm.nih.gov/pubmed/17281685  
 
http://www.ncbi.nlm.nih.gov/pubmed/2875719  
 
Hm, maybe this explains why it's hard for me to stay awake using headphones at night. What if everyone at head-fi is hopped up on serotonin? 

 

[davidsh]

This is an interesting subject. Some time ago I suspected headphones, especially planars giving me headache. Never got to the bottom of it. I do feel less closed in and more clear headed with electrostats on.
It might all be placebo and thought up.

 

[castleofargh]

This is an interesting subject. Some time ago I suspected headphones, especially planars giving me headache. Never got to the bottom of it. I do feel less closed in and more clear headed with electrostats on.
It might all be placebo and thought up.

 for me, more weight=  tensed muscles around the cervical= headache after some time in the same position.  and I concluded it was that and not magnetic field because a helmet gave me the same symptoms ^_^.
might not be the only problem with headphones, maybe magnetic field, maybe the fake soundstage with 180° sound sources(I do feel better with crossfeed), maybe the signature of specific headphones? it's hard to know what is responsible for headaches(maybe all of the above?).

 

[davidsh]

 

This is an interesting subject. Some time ago I suspected headphones, especially planars giving me headache. Never got to the bottom of it. I do feel less closed in and more clear headed with electrostats on.
It might all be placebo and thought up.

 for me, more weight=  tensed muscles around the cervical= headache after some time in the same position.  and I concluded it was that and not magnetic field because a helmet gave me the same symptoms ^_^.
might not be the only problem with headphones, maybe magnetic field, maybe the fake soundstage with 180° sound sources(I do feel better with crossfeed), maybe the signature of specific headphones? it's hard to know what is responsible for headaches(maybe all of the above?).

Yes all of that is absolutely true, though the sigmas weigh more than 400 grams. Headaches can be due to many other things too.

 

[mnarwold]

When I wear my HE-500s they tend to put me to sleep 

 

[davidsh]

When I wear my HE-500s they tend to put me to sleep 

I can't sleep with them on because the pillow blocks the free passage of air making the sound worse which annoys me.

 

[mnarwold]

I can't lay down with them either. I fall asleep while sitting, which is unusual for me. I went from SR-225 and they certainly didn't do that. I'm not sure what it is about the 500s that does it. The weight, the great sound, my stunningly good looks while wearing them ...

 

[KamijoIsMyHero]

One of the best looking headphones for taking selfies, helps with a pretty face as well. The grado is probably too bright to sleep with.