There are several aspects of the Hum phenomenon that help explain why there have been very few scientific investigations into it conducted under the auspices of major educational institutions. One reason is that, thus far, there are no external metrics available for quantifying it. Anybody can claim to hear the Hum and there is no way of verifying that they can. A second concern is that because it is self-reported and subjective, it is challenging to ensure that we are reliably addressing the same dependent variable in each instance. Further muddying the analysis are obvious and classic sources of annoying low frequency noises, such as trains and heavy industrial activity, and it is unfortunate that some of those noises have been referred to as “hums”. The Hum referred to here and in other formal literature has some specific characteristics that differentiate it from other noises. Indeed, there is evidence that the Hum may not be a noise in the usual sense.
Because the vast majority of the population cannot hear hums where they live, it is natural for them to be skeptical about the claims of hearers. Further confounding the issue is the reasonable claim that the Hum may not in fact be a sound in the typical sense of the word, but rather a bioacoustical reaction rooted in some combination of electromagnetic, geomagnetic, infrasonic, and other factors. The unexplained nature of the phenomenon opens the door for all manner of speculation, even conspiracy, as to its cause. Numbers of news stories about the Hum have been intentionally presented in a light-hearted, comical, or “spooky” manner. The Hum even warranted unfortunate mentions on television shows that deal in conspiracy, paranoia, and pseudoscience. This not only downplays the suffering that many hearers experience and lumps them together with those suffering from hallucinations, but distances serious researchers who do not want to be attached to what some might consider to be the realm of pseudoscience, ghosts, and UFOs. There have been sporadic reports that a scientist or researcher has “solved” the Hum. In one such case, it was reported that the Hum was caused by mating fish, in another it was reported that people have simply trained themselves to hear the Hum. In most of these cases it is clear that the commentator has a weak grasp of the topic, or is focusing on a particular source of noise that somebody has labeled as “The Hum”. When we examine the history of the Hum and its worldwide distribution, we are left with no convincing explanations for its cause.