There have been many private investigations into the Hum. Most of these have not met rudimentary requirements for controlled scientific research. Indeed, numbers of people have taken a priori positions on the source of the Hum, and then directed their efforts to proving that they are correct in those assumptions, even in the face of obvious logical problems with their position. For example, there is a school of thought among hearers that cell phone towers are responsible for not only the Hum, but a sequela of other physical and medical symptoms. When asked how that explains why the Hum started in Britain in the 1970s when there was no widespread use of that technology, the subject is changed, or they retreat to a stubborn position that cherry picks evidence that fits the hypothesis. This generalizes across hypotheses, whether it be microwave towers, the LORAN navigation system, or high voltage electricity lines. Each of those carries logical flaws (Deming, 2004).
It is clear that some individuals performing their own research may be earnest but do not have a grasp of the basic science involved; for example, it is common to see writers who evidently do not understand the differences between sonic and electromagnetic energy, or that the word “frequency” can be used in several contexts. Others do not understand the concept of radio frequency (RF) skin depth, and because they cannot silence the Hum with foil shielding, they incorrectly assume that the source of the Hum cannot be electromagnetic radiation. Their speculations may be interesting, but they do not contribute to a useful research corpus. When scientifically literate individuals such as engineers, sound technicians, and so on, perform their own research, they are often overwhelmed with the multitude of independent variables that may be operating. Very few researchers anywhere in the world can draw upon journeyman or expert knowledge in: electromagnetism and radio theory, atmospheric theory including ionospheric heating and electron precipitation, bioacoustics, neuroscience, geology, and psychology. Therefore a team of experts is required. Such experts work for large universities who receive and give funding for research. As explained above, the Hum is not a priority at all, and therefore such a team of experts will never come together if they expect to get paid for their work.