[xnor]

Hey,
 
headphones with more powerful magnets have become more popular in the last year or so. Especially planar magnetic headphones seem to have many strong magnets.
 
 
I was wondering if there is any effect on the brain, and stumbled upon this:
 

Researcher	Field strength Used	Experimental Results
Transcranial Magnetic Stimulation	1 Tesla [T]
Wieraszko, 2000	2.5 Millitesla	Magnetic fields exerted effects on spikes from hippocampal slices in vitro. Link
Dobson, (et al.) 2000	1.8 Millitesla	Interictal epileptiform activity enhanced and suppressed in temporal lobe epileptics. Link
Thomas (et al.), 2007	400 Microtesla	Pain reduction in patients with fibromyalgia. Link
Huesser, (et al.) 1997	0.1 Millitesla	Caused changes in EEG parameters. Link
Marino (et al.), 2004	1 Gauss	Changes in EEG during presentation of Magnetic fields. Link
Carrubba (et al.), 2008	1 Gauss	Evoked potentials detected. Link Also found - similar effects at two gauss or 0.02% of TMS. Link
Brendel, (et al.), 2000	86 Microtesla	Melatonin suppression following in vitro pineal gland exposure to magnetic fields. Link
Bell (et al.) 2007	0.78 Gauss	field-induced alterations in EEG. Link
Vorobyov, (et al.), 1998	20.9 Microtesla	EEG differences in rats. Link Also found - similar effects more recently. Link
Persinger, Michael	1 - 5 Microtesla	This is the field strength used in the God Helmet.
Jacobson, 1994	5 Picotesla	Direct correlation of melatonin production with magnetic field stimulation. Link
Sandyk, 1999	"Picotesla range" Example: 500 picotesla	Magnetic fields improve olfactory function in Parkinson's disease. Link

 
 
 
Maybe someone with a magnetometer can measure the field strength of popular headphones that seem to have very strong magnets?

 

[proton007]

Most effects seem positive. I wonder if it affects enjoyment as well?

 

[xnor]

  Most effects seem positive.

Well that is because medical research is trying to find new treatments, not new ways to hurt people. They stimulate only very specific areas of the brain by pointing the magnets there.
 
With headphones you basically clamp magnets onto the side of your head.
 
 
With strong enough magnets you can disturb the brain so much that the subject cannot speak anymore, or sing. With weaker magnets it seems to be possible to make people see things that are not real, feel surrounded by others or feel a presence in the room when they're completely alone (search youtube for "god helmet"), etc.
 
Granted, most of this research didn't use static magnetic fields but changing fields with frequencies ranging from 1 to about 60 Hz.
 
 
 

 I wonder if it affects enjoyment as well?

I'm sure you could trigger all kinds of emotions (good and bad) with magnets.
But I have no idea what magnetic fields of headphones at the side of your head do. Maybe not much since these fields are fairly static? As for their strength, we'd need someone to measure that...

 

[qwick]

There is an electro magnet in the driver pushing/pulling away/toward the magnet. The magnet is static but the coil is AC and can dip down to the top of that range no problem.

The difference is intensity and distance. I assume headphones are not producing a field quite powerful and/or close enough to cause any noticeable effects.

However, cranking the volume can influence smiling....

 

[xnor]

But the magnetic field produced by the coil would be magnitudes weaker than the permanent magnet.
 
I'm not so sure about the "not quite powerful enough". I mean people have posted that they could use their headphones like magnets. Doesn't sound that weak to me.
 
 
Also, planar magnetics:
 
 
Small, but many very strong neodymium magnets.

 

[65535]

 
With strong enough magnets you can disturb the brain so much that the subject cannot speak anymore, or sing. With weaker magnets it seems to be possible to make people see things that are not real, feel surrounded by others or feel a presence in the room when they're completely alone (search youtube for "god helmet"), etc.
 
Granted, most of this research didn't use static magnetic fields but changing fields with frequencies ranging from 1 to about 60 Hz.
 

Fascinating, so how do people manage to survive and talk to technicians during MRI sessions? Those units range from sub Tesla to mulit Tesla field strengths.

 

[manbear]

Magnets... How do they work?

 

[xnor]

  Fascinating, so how do people manage to survive and talk to technicians during MRI sessions? Those units range from sub Tesla to mulit Tesla field strengths.

I guess duration, change and locality (where is the magnetic field) are extremely important.
 
For example, experiments have shown that pointing strong magnets to the left of your brain stops you from speaking but you can still sing. Pointing the magnets to the other half of your brain and suddenly you cannot sing anymore but still speak. This is of course with rapidly changing magnetic fields.
Also see: http://en.wikipedia.org/wiki/Magnetic_resonance_imaging#Safety_of_MRI: peripheral nerve stimulation (PNS)
 
 
With headphones there are no such rapidly changing magnetic fields however.
 
 

Magnets... How do they work?

That reminds me of headfon.. nevermind, have to be careful nowadays what I write.

 

[65535]

A person in an MRI experiences an incredible magnetic field around the entire portion of the body in the tube. Even outside the tube the field is incredibly strong.
 
It's also a constant field not variable not alternating.
 
http://www.youtube.com/watch?v=6BBx8BwLhqg
 
If that has no ill effect on people you can be sure there will be no effect from a smaller field.
 
Magnets do not interact with human tissue on an appreciable level.

 

[xnor]

  A person in an MRI experiences an incredible magnetic field around the entire portion of the body in the tube. Even outside the tube the field is incredibly strong.
 
It's also a constant field not variable not alternating.
 
http://www.youtube.com/watch?v=6BBx8BwLhqg
 
If that has no ill effect on people you can be sure there will be no effect from a smaller field.
 
Magnets do not interact with human tissue on an appreciable level.

No, it's not only a permanent field:
http://en.wikipedia.org/wiki/Physics_of_magnetic_resonance_imaging
There can be permanent magnets in the less strong MRI scanners, but there are also electromagnets for the oscillating magnetic fields that are needed for the imaging.
 
Also, check this out:
Quote (source):

In the study, the researchers discovered that rats exposed to a 60-hertz field for 24 hours showed significant DNA damage, and rats exposed for 48 hours showed even more breaks in brain cell DNA strands. Exposure also resulted in a marked increase in brain cell apoptosis, or "cell suicide," a process in which a cell self-destructs because it can't repair itself.
 
A previous study showed similar damage, but it was conducted at 10 times the intensity and rats were exposed for just two hours. That indicates that the effects of exposure are cumulative, and duration can be as damaging as intensity, said Henry Lai, a UW research professor who conducted the study with fellow UW bioengineer Narendra Singh. "In real life, people get this kind of exposure in brief doses – three minutes of exposure to a blow dryer, five minutes of exposure to an electric razor," Lai said. "We found that this could add up over time and could eventually lead to some health effect." Since Lai first reported findings of magnetic field-induced DNA damage in 1995, several laboratories in Europe and India have reported similar effects.

In the rat study they used 0.01 mT (millitesla).
 
But again, that's with a changing magnetic field.

 

[65535]

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.

 

[65535]

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

 

[esldude]

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?

 

[proton007]

I wonder what's the strength of the field generated by speakers? In any case, the number of hours (per week lets say) one uses these devices on average is pretty low.

However, radio waves are what we should be worried about. The number of phones and other devices have increased exponentially, the studies need some updating.

 

[qwick]

Thankfully these radio signals are non ionizing (they don't break DNA chains) so they're not cancer causing. They only cause localized heating like a microwave oven set really low. The most significant source is your cell against your ear. Inverse square law!

Much of the cell heat is from the CPU and other components.

Remember humans are not affected by huge magnetic fields like EMPs that can fry electronics. I thinks the ones that have measurable affects on the brain are very specific and strong.