What Is That Mysterious Hum?

In areas around the world, a mysterious hum phenomenon has been reported, although the source of the mysterious noise is not always known.

The mysterious hum is a phenomenon or an assemblage of phenomena that involves extensive reports of a persistent and obtrusive low frequency humming noise that is generally not audible to everyone. There have been wide reports in the United Kingdom and the United States of such a phenomenon. Most of the time hums are prefixed with the name of the jurisdiction where the phenomenon has been publicized such as the Taos Hum, the Windsor Hum and the Bristol Hum.

Explanations For The Hum Phenomenon

There are certain possible explanations as to why phenomenon such as the hum occurs, and they include:

Mechanical Devices

Despite the hum being described as sounding like a diesel engine most of the reports have not been linked to a specific mechanical source. A good example is the hum case reported in Kokomo, Indiana which is a city with heavy industry. The Origin of the hum was thought to have come from two sources, Daimler Chrysler casting plant's 36-hertz tone cooling tower while the second one was a 10-hertz tone from the Haynes International plant's air compressor intake. However, following the correction of those devices, the hum persisted. There have been two cases of hums traced back to mechanical sources such as the West Seattle Hum which was linked to a vacuum pump used to offload cargo from ships by CalPortland. The other case was the Wellington Hum which was thought to have resulted due to a visiting ship's diesel generator. A hum in Windsor, Ontario is presumed to have originated from a steelworks on Zug Island's industrial area close to Detroit.


Tinnitus is the perception of noise or a ringing in the ears and is a common problem that affects approximately 1 in every 5 people. The theory that Tinnitus is a possible explanation for the hum has a short coming since it fails to explain why the hum can only be heard in certain geographical locations. Human ears do not have the ability to generate their own noises which are known as spontaneous otoacoustic emissions (SOAE). Research shows that between 38% and 60% of adults with normal hearing have spontaneous otoacoustic emissions even though a majority of them are not aware. Researchers who examined the towns hum concluded that otoacoustic emissions were a likely possibility for the cause.


The West Seattle Hum is considered to have been related to the toad fish known as the midshipman fish. A previous hum reported in Sausalito, California and the west coast of the United States was concluded to be the male midshipman's call. In the UK a hum reported in Hythe, Hampshire was believed to have been produced by the sonic fish according to the Scottish Association for Marine Science.

The Effects Of Mysterious Hums

An estimated 2.5% of the population tend to have a lower than average frequency threshold meaning they are most bothered by low sounds that are inaudible to most people. Generally, this type of sensitivity only causes occasional discomfort when a big diesel truck passes by. However, those who live near geographical hum spots find it more difficult. People who live around such areas frequently complain of body vibrations, nausea pressure in the head and either loss of concentration and sleep or both. The most frequently reported complaints of humming is annoyance which slowly accelerates to stress which when coupled up with other factors can lead to the deterioration of health or the general well-being of a person. People who cannot hear humming sounds do not suffer any effects when they are exposed to them.

What Is That Mysterious Hum?

RankHum LocationProposed Source
1Kokomo, Indiana, USAAir compressors from industrial plants
2West Seattle, Washington, USAVacuum pump offloading cargo ships
3Windsor, Ontario, Canada Zug Island industrial area
4Sausalito, California, USAFish mating hum
5Taos, New Mexico, USAUnknown
6BorneoBoiler testing
7Bristol, EnglandLocal factories/vehicular traffic
8Bondi, Sydney, AustraliaUnknown
9Auckland, New ZealandUnknown
10Largs, ScotlandTransmission masts

More in Environment