THE HUM FAQS  ( Frequently Asked Questions) by DR CHRIS BARNES GW4BZD

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1.    What is the HUM?


An anomalous sound heard by between 2-11% of the population mainly at night, mainly indoors and in mainly industrialised countries, although a similar thing has been heard due to volcanic action in Hawaii.  Hearing maximises in the 50-60 age groups but the author is Aware of people as young as 24 and as old as 78 who presently hear the HUM.


2.    What does the HUM sound like?


Any description of a sound or noise has, by definition, to be purely subjective. Those who hear it describe it as like a throbbing diesel engine or a distant fly, bee or wasp trapped in a bottle.  Sometimes the sound is perceived as though it is just behind one ear. Sometimes physical vibrations can be perceived as well, particularly if lying in bed.  Sometimes the pattern heard is more complex and may sound almost like music, Morse code or digital code. Sometimes the patterns speed up and slow down other times they are constant. Sometimes the noise sounds more ‘digital’ like ‘phuts’ with a very fast rise time. 


3.    What causes the HUM?


The author’s presently held Scientific opinion is that the HUM is caused by certain crucial combinations of infrasonic and acoustic sound and/or ground borne (seismic) vibrations present only at certain locations and/or in certain buildings which may be from more than one source* including power lines and gas mains behaving badly and including wind turbines and hydro power stations and is experienced as a result of an inner ear feature we all possess known as cochlear non-linearity.   Sensitization of the ear to the Hum may include radio signals of various frequencies, Magnetic# and Electromagnetic fields but these are NOT the direct cause of the Hum only catalysts for it.  Coincidently the Electricity grid could also be modulating the local gravitational field giving rise to infrasound.  Deaf people may hear the Hum through bio-magnetic or bio-gravitational detection. World electricity grids at 50 and 60 Hz can even interact in space to give the Hum!!   In all probability the HUM does NOT have one universal WORLD –WIDE cause. It is simply a facet of modern living and modern houses and modern power systems particularly those with PME ( protective multiple earthing) .  

 * The classic proven case of this was at Kokomo where separate sources of 10 and 30 Hz were traced.  The laws of physics mean these would only

Produce the Hum at certain locations.  # If you want to know if you are magnetically sensitive, try standing underneath high voltage pylons with your fingers poked firmly in your ears to cut off all external sound and see what happens, there should be a direction effect if you are .

4.    How come I just started hearing the HUM?


It could be your age. The author’s hypothesis is that as our high frequency hearing sensitivity starts to fall off with age our low frequency sensitivity boost up to compensate for it .  It could be you just moved house to a location which has the right frequency components for the HUM, SEE 3 ABOVE. It could be you just had double glazing fitted!

    It could be a new factory, industry or power plant has opened up added a frequency component needed for the HUM.   There is scientific evidence to support the idea that people’s low frequency hearing threshold will become more acute when exposed to infrasound.  The author has now also shown  some  that certain radio frequency emissions may also sensitise the ear to the HUM BUT  they are facilitators rather than cause.    So it could be a new cell phone mast, TETRA or TV or radio mast has just opened up.

 Evidence that most cases of the HUM are not due to radio frequencies alone come from the fact that hearers still hear it in  a Faraday cage.  But remember the magnetic vector potential can enter a Faraday cage


5.    Why do I only hear the HUM at night?


At night it is generally quiet there is less masking noise. There is less vehicular movement to ‘stir up’ the HUM.  Movement is important because if your Hum has more than one component they may need to arrive ‘coherently’ this means with their wave crests in phase or at the same time for you to hear the Hum so moving cars and gale force winds etc can disrupt this process. Traffic may disrupt or mask both airborne sound and narrow-band ground-borne vibration.   


6.    Why do I only hear the HUM indoors?


Your house acts like a giant acoustic sounding box. Double glazing and cavity walls actually make matters worse! Cavity walls may conduct ground borne vibrations such as those from idling trains, hydropower, wind turbines etc. and radiate them as infrasound and sound. Double glazing blocks off high frequency sounds but is next to useless below 150Hz.

Piezo electricity in brick can also radiate mains hum as a weak acoustic sound.



7.    Why don’t ear plugs work very well?


Ear plugs offer very little attenuation at low sound frequencies.  Wax offers far more attenuation than foam at low frequency.

Natural masking noises the wind and waves or recordings thereof are much better.   Also you might find a combination of ear plug and radio frequency screening material better. 


8.    Why does the HUM seem to vary with the weather?



The weather effects the way sound and infrasound moves through the atmosphere. If any of your HUM components are coming from any distance say 2-1000 km they WILL ALWAYS be changed by the weather especially winds.  The weather effects ground borne vibrations. The weather affects electrical leakage currents in walls too.   Also the weather has been shown to be affected by anthropogenic activity so is the Hum. In North West Britain it is more likely to rain on Tuesdays and Saturdays strangely the Hum has been shown to peak on these days as well.    





9.    We had two feet of lying snow and the HUM went!


It sounds like your HUM is carried in a ground borne vibration or surface wave. The weight of the snow damped the vibration.


10.                  Our HUM went after 911 when all aircraft were grounded!


This is a more difficult one.  Either your HUM is directly due to sound or infrasound generated by aircraft maybe you live under a corridor?  Alternatively aircraft generate aerosol into the JET stream which changes the way sound travels from other sources. 


11.                  Do some geographies favour the HUM more than others?


The HUM seems to be perceived in COASTAL regions and MOUNTAIN regions more than others.   In mountain regions there are natural sources of infrasound which could combine with weak acoustic sounds to produce the HUM.   Mountain regions often have

Hydroelectric power plants which could provide ground vibrations.


In coastal regions infrasound can also be generated naturally e.g. booming sand dunes but also from oil drilling, seismic exploration and wind farms.  There is often more railway (rail-road) activity too.  Idling diesel engines in sidings are a big problem in the UK.


12.                 I still hear the HUM in an anechoic chamber!!


These are only good down to about 150 Hz. The frequencies that cause the HUM are often much lower than this.  


13.                 I stopped hearing the HUM in a deep limestone cavern about 150 metres down.

It sounds like one of your HUM COMPONENTS is a surface acoustic vibration which will not penetrate so deep in the earth.  Also not many radio frequencies can enter here.


14.                 I hear the HUM louder when its night and I look outside!!!


You don’t say whether there are street lights.  This is a very hard question to answer anyhow but could be due to synthesesia  ( the brain handling duelled sensory input).   If your HUM is arriving partly form natural atmospheric infrasound there will be in phase natural speckle of this in the optical background.  Your eyes sub consciously detect this ands duel it with the signal from your ears.   


If on the other hand you are looking at street lights there may be modulation of the light intensity by ground vibration or mains fluctuation. If your HUM is PARTIALLY due to a vibration underground or a Power Generating facility the two might reinforce. 




15.                 I hear the HUM loudest when it’s a full moon!!


This might be due to more speckle as in the answer above or it could be due to the effect on tide and tilt altering your local seismic propagation. ( The way ground vibrations move is altered by the moon)

Also the Hum seems to depend on planetary cycles suggesting a complex interplay of natural and anthropogenic ( people made) processes.


16.                 My HUM gets worse before a big earthquake and goes away for about 24 hours afterwards.


Surface seismic waves propagate or move through the earth differently according to how much stress is in the earth’s crust.  There harmonic content is also different. Waves from hydro-power plants are susceptible to this and travel hundreds or even thousands of kilometres.  Your HUM is being affected by how much of this component you receive. The propagation of any ground borne vibration will be affected by the amount of stress in the earth’s crust.


17.                 Can I get relief from the HUM ?


You could move house but this drastic measure doesn’t always work. You could emigrate but as more of the World becomes industrialised there are fewer and fewer HUM free locations.  You can use masking noises and relaxation techniques.  For some, long distance car journeys induce a temporary deafness to the HUM, 48 HOURS or so for a 200 Km journey, the so called ‘holiday effect’ - well worth it now and again.