Estimating the acoustic power of World sources for the Hum by Dr C. Barnes, Bangor Scientific Consultants  by  Dr Chris Barnes Bangor Scientific Consultants 24th March 2012


The general properties and history of the Hum are described. The more specialised properties of the Bangor Hum are re-iterated. Possible acoustic power levels for all the likely Hum component sources in the World are calculated and then reduced to a power index per Hz of peak contributing bandwidth. The world power grid is the greatest single contributor but aircraft and natural gas compressors are also very probably relevant.   Other infrasonic sources such as wind turbines must not be ruled out at a loval area level.


Unusual hums have been documented in Britain and Ireland since as early as the industrial revolution. However, the first instance of a humming noise with the characteristic today recognised as the Hum i.e. a mainly nocturnal low pulsating quasi-periodic drone was first reported in Britain in the 1970’s and more latterly in the USA in the 1990’s.  The Hum is now heard extensively in many parts of the World.

It has been postulated by Professor David Deming that the original British and American Hum correlated in time and space with the flights of US TCAMO aircraft and in particular could have been due to their ELF radio transmissions.  Whereas the present author agrees that these and indeed other aircraft could be connected with the Hum, feels it more likely that the offending component is infrasound not electromagnetic radiation.

People who hear or perceive the Hum are often referred to as ‘Hummers’.  When the author moved to his present address, his wife started hearing the Hum in late 2003. Some two years later the author too became a Hummer. So annoyed and frustrating was his experience and the nocturnal disturbances which have resulted, that he decided to commit considerable scientific effort towards a far more comprehensive understanding of the Hum than had hitherto being available. Seven years on the work continues.  There have been ups and downs, hypotheses and thwarted hypotheses, complicated theories and simpler theories but in balance certainly much more appears to be known and understood today about the Hum as a result of his efforts and furthermore the Hum is now discussed openly in Internet Forums and by Acousticians and Physicians rather than being relegated to the World of the paranormal.

Indeed a truly enormous amount of research has been conducted in relation to the Hum experienced in Bangor which reading people’s responses on the various forums and speaking to other people afflicted by the Hum elsewhere in Britain and world-wide seems very relevant.

Very briefly the conclusions about the Bangor Hum are as follows:

·         It seems only to be manifest when narrow band infrasound and acoustic signals are simultaneously present.

·         These signals usually contain harmonics and inter-harmonics of the mains frequency and infrasound between 1-20 Hz when subjected to FFT waterfall analysis.

·         Bangor’s Hum seems to be manifest mainly at night and when power line harmonic radiation and complex low frequency ground currents thought to be related to the UK and US mains frequencies can be detected.

·          It seems worse at specific distances from VHF and UHF transmitting antennas. The hypotheses here are that either pulsed electromagnetic radiation at these frequencies sensitises the ear in some way or that actual Bragg matching between the radio frequency and acoustic wavelengths is relevant. 

·          Its intensity varies consistently on certain days of the week over a several year period suggesting it is due to an anthropogenic source. 

·         It is usually possible to screen out the Hum using wax ear plugs in a non-conventional sealing  manner   shaping them as a flat plug rather than as a tapered plug.  However, if the interplanetary magnetic field points southward then some component of the Hum is virtually impossible to screen and this coincides with the appearance of strong magnetic low frequency comb spectra which can be picked up by a solenoid or torroidal coil. 

·         Thus on some occasions the Hum behaves as though it is a simple acoustic signal and on other occasions as though it were a magneto- acoustic signal. 

·         The Hum also seems to depend on planetary cycles with its magnitude peaking around the time of the full moon. This can be understood by changes in the stress in the earth’s crust and changes in tilt due to tides which will both change the propagation of a seismic signal or signal with a seismic component.

·         Presence of a seismic component in addition to airborne components is also suggested in that different frequencies are picked up on the house walls than in the air or outside.

·         Although the Hum contains several frequency components it can be heard to stop or reduce when any one of which is blown out by a wind of appropriate strength and direction. Likewise moving vehicles can temporarily disrupt the Hum.

·         The Hum seems to weaken as the 300mBar jet stream moves more distant. This could be related either to a component of the Hum arising from the jet stream e.g. aircraft or ship noise or because its position is related to planetary cycles.

·         There is could also be a seismic connection here. The author has noticed that the jetstream often makes a sudden unpredictable change of direction just before, during or after a significant earthquake.  

·         The closest seismic source for a contribution to the Bangor Hum is the Pumped Storage Hydropower plant at Dinorwig.

·         The Hum is almost the sound of silence in that it is perceived more strongly if the part of the audio spectrum between 100-320 Hz is completely quiet.

·         The History of the Hum in Bangor dates to well before the present author began hearing the Hum. He  recalls a colleague Dr Kevin Doughty being asked to explore a Hum in nearby Tregarth in the mid 1980’s which would be only a year or so after the Dinorwig plant was opened.   


Hums with multiple frequency components some of which have travelled considerable distances are notoriously difficult to tie down. Occasionally Hums have been reported where the sound sources have been local such as Kokomo(ref)  or from District Heating plants (ref) Refrigeration units (ref), Wind Turbines(ref) or Sewage Pumps (ref) or relatively local Hydro-plants (ref) and these may be easier to mitigate.  However, Hums which are the former would seem to be springing up all over the world. One must examine therefore proliferating acoustic sources which could give rise to a more world-wide Hum.   

On the face of it there is sufficient near-field coupling from World’s electricity grids to account for most Hums.  On the other hand infrasound sources less than 10 Hz will also reflect from the ionosphere (ref) and would be expected to do so at night when the D-layer of the ionosphere is closest to earth i.e. coincidentally   at the same time as power line harmonic radiation is observed.

Significant acoustic power sources which could supply a low frequency and infrasonic component

The only sources considered are those which are proliferating and might give rise to the Hum. Sources have not been included if they do not fit in with the time line of the Hum.

All the power sources considered are fundamentally engines or similar mechanical machines. The estimate acoustic power of engines and mechanical machines usually varies from about .01 to .1 % of their mechanical output power (

The easiest way to present the data is in a table.








0.01 W

250 million





300 W


1.5 MW

1-600 Hz


Peak 2-10Hz






1-1500 Hz

peak 85-89Hz


Natural Gas



13.32 MW

10-150 Hz


peak 31-33Hz

6.66 Mi

Wind Turbine




1-1200 Hz

peak 1.7 Hz-20Hz



715 GW


71.5 MW

2-50 Hz

1.5 Mi

All electricity



10 GW

12.5 -300 Hz


In World



Electricity  (as fundamental e/m radiation)

Only 5 watts!!*


 Results and Discussion

In the 1970’s motorways and gas mains were blamed for the Hum ( Fox).  The table shows that in terms of an acoustic energy source all the cars in the World simply do not feature in the Hum.

World electricity grids as acoustic sources have maximum capacity to cause the Hum on a World -wide basis, followed by Jet Aircraft and Natural Gas Compressors.   That is not to say the other sources considered are not relevant. For instance wind turbines will become more relevant in future and for local Hums.  Super-tankers may be very relevant in coastal areas.


All the sources can provide a Hum with ground borne seismic components.   The Hum in Bangor seems to have a complex makeup and require coherence in multiple sources. A Hum which is a combination from aircraft and power systems and their generation components or is a combination of the latter with gas compressor noise may best fit the bill.

The radiation of fundamental frequency power  (50/60 Hz) beyond the near field from power systems is *minuscule based on the paper of Hafemesister (1996).

However there will be significant radiation at higher frequency harmonics.


Only Hydropower and Wind Turbines can provide the lowest frequencies ever observed in the Hum spectra. Beats in world power systems can provide a 10 Hz infrasonic component so can Hydropower and Wind Turbines. In this respect a unique coherence with power system fundamental and harmonic noise will exist with this type of Hum which may account for the intensification when the interplanetary field swings southwards. It is not known if all Hummers are sensitive to the magnetic component of the Hum.    Many Hums have components around 30 Hz. Natural gas compressors can provide this component.   High pressure gas mains and high voltage power grids often share the same corridors there is opportunity for cross talk.  It should not be forgotten that Hydropower infrasound in the guise of seismic signals can travel many hundreds or even thousands of kilometres underground (refs).  Such underground propagation pathways will be disturbed during World seismic activity and this could easily account for the apparently spontaneous appearance and disappearance of the Hum at some locations. 

 Harmonics of power systems are also ubiquitous. A frequency around 90 Hz has been noted in the Bangor Hum on occasions. Bangor is under a busy air-lane so aircraft could be the source of this component. 

It should not be forgotten that building and room resonance may exacerbate Hums and may account partly for their apparently random distribution.

The conclusions reached here are not inconsistent with other work of the present author (refs) which suggest at least in Bangor the Hum is due to an anthropogenic source and also correlates with minimum load on the uk power grid (ref) the very times Dinorwig will be pumping. Thus Hums the World over are highly likely to be caused by a combination  OF ACOUSTIC AND SEISMIC   signals from Pumped Storage Plants, Gas Mains and Electricity Grids all combined with the possibility of additional tonal contributions from a major air-lane  in the frequency range 52-155Hz (ref).  The Hum may thus conceivably be   a sad and unfortunate coincidence and possibly being due to a combination of signals which could limit successful prosecutions on the part of those afflicted.

However, as medicine comes to realise the serious problems caused by WTS and VAD designers of power systems, houses and infrastructure might hopefully take on a policies to mitigate or avoid future intensification of the Hum.   The author is a firm believer that if clean energy must be used, off- grid islanding and radical redesign of household wiring systems might at least spare some us from the Hum!   

Finally, some have speculated that HAARP may be a potential cause of the Hum.    HAARP has only a mere 3.6 MW ERP at source and most of the publications relating to ELF suggest that only a few watts of ELF are produced. The author feels, on balance, therefore that HAARP is not the source of the HUM, the latter of course also pre-dating HAARP.  

Further work

The Bangor Hum has been previously been shown to be due to an anthropogenic source. Further work is now under way to try and understand the evolution of all the World’s most publicised Hums.