In this very moment, when you sit next to many WiFi devices, probably in an urban region with many mobile phone cells and a that, you can forget about the effect of the magnetic field of the earth onto your body. It is just negligible.
One odd thing I've come across lately are accounts of the effect of MRI magnetic fields on depression. https://www.scientificamerican.com/article/do-mris-treat-dep....
Since ECT and other forms of brain damage have been shown to offer temporary relief from depression when endorphins are released in response to the damage, I wonder if MRIs have a similar effect.
That's the reason why the cell phone in your pocket has a higher impact on your reproduction organs then on your brain. And why the cell phone tower (on average) has less impact on your body then probably any device in your room.
The wireless headphones are recieving most of the time, that's why they should put little harm on your brain. Better care about keeping your phone in a bag instead of your trouser pocket.