@sokogear Get a dB meter.
Play pink noise through your system at a level to read at about -50 or -60 dB. Use a fixed position for your meter. Turn on the Schumann device.
Read the meter, It should increase by a 1/4 to a 1/2 dB. .
A small change but still significant. Any fractional dB increase is still a lot of energy.
I was done with this topic for now but can’t let incorrect information go:
No, this can’t be assuming the device is emitting em radiation at that frequency ( not sound) it will NOT show on a sound meter. You would need a sensing device sensitive to that wavelength/frequency in the EMR spectrum (se link I provided above) to detect that. Not a sound/db meter.
This argument is all over the place. One minute its effect of EM radiation from devices like this and transformers on electronic circuits, next its the same device producing sound not EMR that you will detect on a sound meter.