A few years ago I posted on this topic, and a few minutes ago I rediscovered why. As evidence piles up against EM-based theories (VLF radio, microwave, etc), I’m leaning toward the theory that the Worldwide Hum is an internally generated perception of sound and in some cases, vibration. Note that there may be external triggers or pre-requisites, such as ototoxic medications, environmental exposure, infrasound, and so on.
So focusing back on medical diagnostics, take a look at this startling experimental result: http://digitalcommons.northgeorgia.edu/cgi/viewcontent.cgi?article=1049&context=papersandpubs.
Allow me to offer an executive summary: When you strike a deep bass note on the piano, for example, the piano string vibrates strongly at that fundamental dominant frequency, which is what you hear. But, the string also vibrates at other frequencies, called overtones. (It is the mixture of these different harmonics and overtones that make each musical instrument and voice unique.) Musicians will know these overtones as the third, the fifth, the seventh, and so on. The fascinating thing is, if those harmonics and overtones – without the fundamental – are played to you, your ear and brain will create the fundamental note for you, and you would swear that you can hear the fundamental bass note being played! I don’t use exclamation points very often, but this is quite remarkable. This effect is called the missing fundamental. The undergraduate researchers in the above paper conducted a brilliant experiment in which they played tones that created an infrasonic missing fundamental. That is, the brain created a note that was below the range of hearing. They measured the brain response using EEG recordings which clearly showed the missing fundamental rising at 18Hz.
So then I had an idea. We should do something very similar. The important lesson from the above study is that there are external experimental techniques that can validate real or perceived sounds. This could separate Hum hearing from schizophrenia, otoacoustic emissions, tinnitus, or other phenomena, just for starters.
We don’t need to create the missing fundamental. If we are perceiving, say, a 47 Hz tone, then the EEG might show that. It also might show whether that perceived Hum disappears in the presence of masking noise, or whether it is persistent. If a 47 Hz signal cannot be read on the EEG, then this will point neurologists toward different hypotheses. It seems to me that no matter what the result, we can use the data generated.
Please let me know if you have connections in the medical world who might be interested in making this happen.