The Hum Questions and Answers

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.

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 and is experienced as a result of an inner ear feature we all possess known as cochlear non-linearity. Other theories of the HUM include radio signals of various frequencies,

Magnetic and Electromagnetic fields and the Electricity grid modulating the local gravitational field. In all probability the HUM does NOT have one universal WORLD –WIDE cause. It is simply a facet of modern living and modern houses.

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 also has some limited evidence to suggest that certain radio frequency emissions may also sensitise the ear to the HUM I.E 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.

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.

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!

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

Ear plugs offer very little attenuation at low sound frequencies.

Natural masking noises the wind and waves or recordings thereof are much 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.

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.

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

These are good down to about 150 Hz. The frequencies that cause the HUM are 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.

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.

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.

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, well worth it now and again.