8 Unsolved Mysteries of the World

The town of Taos, in north-central New Mexico, has been home to many famous residents including Julia Roberts, Dennis Hopper, D.H. Lawrence, Aldous Huxley and Donald Rumsfeld. It's a small, laid-back artsy community that is also home to an unusual mystery: a resident hum of unknown origin, the so-called "Taos Hum."

A variety of theories have been offered as an explanation, ranging from the mundane to the fantastic, the psychological to the paranormal. Stoned hippies, secret government mind control experiments, underground UFO bases and everything in between have been blamed.

The hum seems to have first been reported in the early 1990s. Joe Mullins, a professor emeritus of engineering at the University of New Mexico, conducted research into the Taos Hum. Based on a survey of residents, about 2 percent of the general population was believed to be "hearers," those who claimed to detect the hum. Sensitive equipment was set up in the homes of several of the "hearers," measuring sounds and vibrations but after extensive testing nothing unusual was detected.

The research revealed, however, that there was not a single identifiable Taos Hum but instead several different ones that people reported; some describe it as whir, hum or buzz. The fact that not everyone heard the same thing was puzzling, and suggests that they may have been reporting subjective experiences instead of objective sounds.
Mystery sounds

Mysterious sounds are nothing new, of course, and Taos is not the only place plagued by unknown noises. In fact, there are dozens of other cities, both big and small, in which some residents claim to hear something strange.Just as there may be more than one explanation for unidentified lights in the sky or along the skyline (including aircraft, clouds reflecting spotlights, car headlights and so on), there may be more than one explanation for unidentified sounds. The mysterious sounds range from a high-pitched squeal to a low murmur to a faint rumble, and the explanations are almost as varied as the sounds themselves.

Though some of these mysterious sounds remain unexplained, many were eventually identified. For example, in 2012 residents in Borneo reported hearing bizarre roaring or snoring sounds beginning very early in the morning and lasting a few hours until dawn. It happened two days in a row, frightening and puzzling locals. Investigation revealed that the mysterious noises were caused by a nearby factory testing their boiler while the plant was closed. In February 2014, a mysterious short-lived "loud droning," "unearthly" sound like in the science fiction film "Independence Day" was reported in the skies over Coventry, England. It baffled residents for miles but an unseen airplane was later revealed to have been the cause.

Some reports of unexplained sounds were later revealed to be hoaxes. For example, a video posted to YouTube in January 2012 by a young Canadian university student near Edmonton, Alberta, contained strange sounds that she asked for help in explaining. The mysterious sounds video went viral, and garnered nearly 2 million views before it was exposed as a prank. In an interview with a local newspaper, she admitted that she made the video "to show my friends and family how easy it was.... and how they shouldn't believe everything they see online."