A
loudspeaker from the Underworld, Local
Active corrosion protection: a possible
feature in Britain’s Low Frequency Noise (LFN) Phenomenon more commonly known
as the Hum by Dr Chris Barnes, Manager at Bangor
Scientific and Educational Consultants, November
2015. E-mail manager@bsec-wales.c.uk
Abstract
The nature and history of the LFN phenomenon in Britain known as the Hum is briefly discussed. A brand new hypothesis that DC and pulsed DC fields due to active corrosion protection systems may actually enhance Rayleigh wave radiation of the Hum however its frequencies arise is advanced and supported to some extent experimentally and by personal observation. . Moreover CP may induce weak time varying magnetic fields comparable with the earth’s natural field to which we humans are presumably sub consciously attuned, particularly with respect to Schumann resonance. A combination of infrasonic and low frequency acoustic field together with a coherent magnetic field appears to be the set of conditions required to generate the most pervasive Hum. Such a set of conditions may have inadvertently been introduced in the UK from the early 1970’s onwards as a result of utility infrastructure changes.
Introduction
The
enigmatic low frequency noise (LFN) phenomenon known as the Hum was first
reported on a widespread basis in Britain in the 1970’s[1]. The Hum is often
considered as distinct from other forms of LFN in that its source often seems
un-locatable and un-recordable [2]
and hearers sometimes report earplugs as being rather ineffective as a
defence. Other than the work done by
the present author [3] and a tiny
handful of Universities in the UK there
appears to have been little serious effort to properly understand the
phenomenon. In fact Hum research has been a field wherein amateur
investigators such as Dawes [4], for
example, have possibly made as many and as significant contributions to those
of academics.
People who hear or perceive the Hum is often labelled ‘Hummers’ and it would seem that in one mode of perception of the phenomenon they are far more sensitive than average to low frequency noise. This does not rule out that there could be other modes of signal perception in some sensitive individuals either not related to low frequency noise or accompanying it such as magnetic perception and these have been discussed by the present author elsewhere [3]. The Hum is sometimes described as the noise of an idling engine or throbbing sound. These are also described as the effects of infrasound [5] .
One
major problem with doing science on a phenomenon such as the Hum
is because relatively few people experience it, one is often left to
rely on anecdotal reports. With the
advent of the age of the Internet and Global communications, hearers of the
Hum, worldwide have formed forums and discussion platforms regarding the
phenomenon [6,7]. This has led some
to suggest that somehow the Hum is now a single worldwide phenomenon. This is very different to the experience of
the Hum in Britain in the 1970’s and the early experiences of the Hum in the
USA in Oregon in 1976 with
an explosion of cases by the early 1990’s.
Where the former was put down to noise from motorways and Gas Mains [8] and the latter only to
a specific set of Industrial sources in Kokomo [9] with all the other US cases remaining unsolved and with one
author, namely, Deming, suggesting that
both correlated in time and space to a certain type of military communications
aircraft [10].
The
present author has come to the conclusion that most modern Hum cases correlate
spatially with renewable energy systems, especially wind power [11] and certain types of
hydro-power. In this latter respect it
is interesting to note that Oregon is one of the USA’s most major source of
hydro-power and is where their Hum was first experienced. Because the Hum is a subjective
phenomenon or possibly group of
phenomena, different people describe hearing slightly different noises. It is a well-known fact that once sensitisation to any sort of LFN has
taken place, the hearer will generally be more receptive to similar frequencies
whatever the source[12] (Oud). If the Hum has predominantly an infrasound compound then clearly it will be
un-recordable using traditional
microphone based equipment. Oud [12] has
discussed the notion of an un-recordable LFN beating with a higher frequency
component and I too have discussed this
in terms of cochlear mechanics [13]. Another reason why the Hum may be very
pervasive for some is if it has an electric or magnetic or gravitational
component. For example a Hum with a magnetic component accounts for why some
can hear the Hum in certain types of deep underground cave [14]. It also accounts for why in some cases earplugs are
ineffective.
The
present author has also discussed the notion of local and distant Hums. Some
distant Hums may involve the ionosphere and atmosphere as a
generating/propagating medium and/or similarly the solid earth. There is a very strong case for the
involvement of power systems in some cases of
the Hum even predating wind energy.
Local cases of the Hum may be caused by acoustic and infrasonic signals
from the same or from multiple sources provided that certain frequency
relationships are satisfied. With
regard to electrical power systems it seems that when they are behaving badly,
due for example, to phase imbalance creating multiple harmonics and
subharmonics and more likely with wind power, the Hum phenomenon also seems
worse. Yet at least in Bangor Wales
and in some of the surrounding area it seems that some of the frequencies
capable of causing the Hum are detectable over ducts carrying each of the three
utilities. See all my papers at
reference [3] for a full explanation
of what is contained in this very condensed paragraph.
The
Hum in Britain began to be reported extensively in the 1970’s when there were
major changes in infrastructure. The
first pumped storage power stations had been built, gas was no longer stored in
large holders but was piped at high pressure and controlled by compressors and
spring loaded regulator stations. Active
corrosion protection began to be used
on power systems, sub-stations, gas distribution and at gas pressure
reducing stations.
The Hum gas or electric or both and
active corrosion protection (CP) a loudspeaker from the underworld, a new hypothesis
In
the 1970’s active corrosion protection began to be used extensively on
pipelines, at power substations and at all gas pressure reducing stations. Although the DC voltage which needs to be
introduced and maintained between the pipe or structure and the set of
protective electrodes is small and the current density likewise because the
volumes/areas covered can be large the rectified current capability of the
protection unit itself can be large.
Thus one can conceive the presence of a non-uniform DC or quasi-DC
(half-wave rectified) magnetic field in the local region of the unit and
immediate underground. Some CP systems
are also pulsed. Some explanations of CP
systems are to be found at references [15]
and [16].
Even in the absence of pulses there is also
present the earth’s ever present field and additional electromagnetic fields
from electricity infrastructure. There
is also the possibility of pipeline pulsations causing pressure wave modulation
of the ion flow and causing additional
induced fields. Thus we may hypothesise we have an underground system not
unlike, but rather more complicated than Magnetoacoustic
tomography with magnetic induction (MAT-MI) which is an emerging approach for
noninvasively imaging electrical impedance properties of biological tissues,
see for example Hu (2011) [17].
MAT-MI imaging systems measure ultrasound waves generated by the Lorentz force,
having been induced by magnetic stimulation, which is related to the electrical
conductivity distribution in tissue samples.
Given the frequencies involved, I would expect our ‘in
street’ or ‘under tarmac’ version of MAT-MI to generate acoustic and infrasonic
frequencies with sum and difference frequencies associated with powerline
frequencies, their sub harmonics as
well as inter alia their inter and intra area oscillation and flicker frequencies and the pulsation frequencies of the gas pipes
involved. Further, I would expect some phase coherence between some of the
acoustic frequencies and magnetic field frequencies involved. Given that human beings have evolved on a
planet where they are exposed to feeble ELF fields ( so called Schumaan resonance)
and have strikingly accordant brain rhythms with the former, see for example
Cherry (2002) [18], I would expect such
acoustic and magnetic signals from the tarmac underworld to be potentially disturbing or even very disturbing to some
humans, viz a viz The Hum.
An
additional facet is that DC currents associated with CP will cause ionic charge
separation and the possibility of
numerous two way electroacoustic effects
such as, for instance, electro seismic conversion or electrolytic style
loudspeaker action. Electroacoustic
phenomena arise when sound waves
propagate through a fluid containing ions. The associated particle motion
generates electric signals because ions have electric charge. This coupling
between ultrasound and electric field is called electroacoustic phenomena.
Fluid might be a simple Newtonian liquid, or complex heterogeneous dispersion,
emulsion or even a porous body. There are several different electroacoustic
effects depending on the nature of the fluid.
Ion Vibration Current/Potential (IVI), an
electric signal that arises when an acoustic wave propagates through a
homogeneous fluid.
Streaming Vibration Current/Potential
(SVI), an electric signal that arises when an acoustic wave propagates through
a porous body in which the pores are filled with fluid.
Colloid Vibration Current /Potential (CVI),
an electric signal that arises when ultrasound propagates through a
heterogeneous fluid, such as a dispersion or emulsion.
Electric Sonic Amplitude (ESA), the inverse
of CVI effect, in which an acoustic field arises when an electric field
propagates through a heterogeneous fluids.
I
hypothesise that this might be a potential amplifier of ground emitted pipe and
other vibrations or an electro –seismic
converter creating ESA for pre-existing a.c. ground currents.
I set up an experimental electrolytic cell to test this notion.
Experimenting with electrolytes and active CP style
signals
I set up
the apparatus as above. A ‘Feedback’
Sine Square Oscillator type SSO603 was used to drive an AC691-N speaker system
and the remote output jack was connected directly across the Aluminium foil
electrodes immersed in saturated sodium chloride solution. The lower electrode was formed in the shape
of a cup to focus sound waves upwards. A
piece of 60/40 solder was used a sacrificial electrode. This was brought into
very close proximity with the cup electrode.
The system could be driven into oscillation from about 100Hz – 8 KHz and
displayed a broad resonance at about 2+/.5 KHz. Even so the emitted sound level
was extremely low and barely perceptible to the human ear. However, it could be significantly enhanced by about 20dB by pulsing on 12 volt DC at approximately 1 second intervals as
shown. Any attempt to leave the DC flow
on continuously was counterproductive to acoustic amplification as the bubble
cavitation noise due to electrolytic action was overwhelming.
This
simple experiment illustrates that at least under laboratory conditions a
pulsed DC current, similar to that used in some CP systems can enhance AC
acoustic emissions. It is thought that
something similar occurs on a grand scale with CP protected buried
infrastructure and the moist earth acting rather as a loudspeaker from the
under- tarmac world. I have previously
mentioned how the Hum in Bangor appears as a very easily damped Rayleigh wave
at my premises and how passing vehicles
appear to very readily disturb it.
Practical Experience.
Neither
my wife nor I had ever heard the Hum before coming to reside in our present
address, which incidentally is located only some 35 metres or so from a spring
controlled gas pressure reducing station with local active cathodic
protection. Even our son hears the Hum
sometimes and he is well below the peak age for Hum perception. Some people report hearing the Hum in the
vicinity of high voltage power lines, I am not talking of corona noise
here. As a scientist and engineer, I
know the difference. High voltage lines
in the UK now almost always share their route corridor with the high pressure
buried gas pipeline grid and are known to induce significant voltages into them
which can disrupt cathodic protection just as much as GIC’s from solar
storms. Presumably all have the potential to give enhanced
ground borne sound and emf production.
This
practical experience seems to strongly support the above hypothesis. Either when AC fields meet CP systems or when
a Gas Pipe is subject to mechanical vibration as with gas pressure fluctuations
in the presence of induced CP the Hum seems to be locally manifest. Yet nothing in this statement detracts from
other causes of the Hum as an LFN or even part preternatural phenomenon whether
locally generated or propagated from afar.
Do the frequencies observed make
sense?
The
propagation speed of sound in soil varies between 50-300m/s. Assuming infrastructure buried at
approximately 1m depth, pseudo resonances in the tens or hundreds of Hz region
are to be expected.
AC
source frequencies available will be 50 Hz and its sub and higher
harmonics. These will also be subject to
modulation by flicker (typically wind turbine blade crossing frequencies and
the like). Natural and anthropogenic
seismic signal frequencies will also be available. Pulsation frequencies of the gas grid will
also be available. Thus frequencies are
available which could match and sustain any likely resonances.
Many
electricity installations as well as gas installations use active CP. CP signals are sometimes pulsed for corrosion
investigations and infrastructure location [19]
(Koleva (2006). This will also complicate the
issue. Since much modern utility
infrastructure runs close together, electromagnetic and acoustic crosstalk
might be to be expected. It is instructive therefore to explore a spectrum
analysis of signals on the various networks.
I
previously made an acoustic study of Bangor and LlanfairPG made in the frequency range 0-313 Hz
approximately [20] and considered the different utilities as sources of sound for
the phenomenon known as the Hum. Essentially, the hypothesis of Vasudevan and Gordon (1977), Institute of Sound and
Vibration Research University of Southampton [21]) was confirmed with regard to the presence of the Hum in the
context of a highly skewed acoustic spectrum but not necessarily within the
context of signal origin. I showed that the Hum generally requires a
substantial infra sound component, some sort of narrow band acoustic signal(s)
of constant frequency within the range 30 -80 Hz and minimal or zero acoustic
sound above that frequency range, this is also exactly consistent with Oud’s
paper [12]. Signals from both the
power grid and gas mains can produce Hum most of the time in parts of the
village of LlanfairPG whereas at the author's house
the Hum comes and goes according to propagation of infra sound and seismic
sound from larger distances away particularly when there is instability in a
particular 400KV circuit in the electricity grid giving rise to sub-harmonic
and inter-harmonic acoustic noise.
I
also reached the conclusion that Hums in the Bangor and Anglesey area are very
likely caused by either the electricity grid behaving badly and/or the High
Pressure gas grid. There was an unknown signal of 14 Hz on the water mains only
found in Bangor within this study. The
gas grid was found capable of generating very similar frequencies to those
obtained with mains sub harmonics but also generates frequencies around 56 and
73 Hz not seen underneath power grid circuits. It is very interesting to note
that Tom Moir recorded a frequency of 56 Hz as being associated with the North
Shore New Zealand Hum. It is believed NZ has similar methods of Natural Gas
distribution to the UK. A frequency of 44 Hz was also observed. This is
suggestive of 50HZ+ /-6 Hz as being potentially present on the gas mains in
Bangor. The much lower frequency
periodicity of the Hum could not be readily recorded and possibly arises as a
result of wind turbine infrasound and/or wind turbine flicker on the 50 Hz
signal.
It
is interesting to note that some kinds of high power pipeline fault finding
equipment which can be connected to CP points produce frequencies of
3,4,6,8.64,98 and 112Hz, see
http://www.vivax-metrotech.com/UploadFiles/image/vLocDM_Brochure_VXMT_Eng_V2.0_20100531%20%28vxmt%29.pdf [22].
Firming up the link with gas
Spring
loaded gas pressure reducers are most likely to introduce pressure fluctuations at
minimal and maximum flow rate [23] and similarly
auditory Hum, see Zafer and Lueker,
Applied Mathematical Modelling (2008) [24]. The author has often noticed the Hum to appear
to peak at about 11pm and 6 am. These
are presumed times when gas flow rate will be changing dramatically as heating
systems switch off and re-start?
Recently major gas mains renewal has taken place in parts of Bangor and
with it the Hum intensity seems to have reduced dramatically. Unfortunately,
one can only make qualitative statements at present and a note of caution
should be raised as quite often pumped storage power begins pumping and
ceases pumping at about the same times as the above [25].
More than just infrasonic/acoustic
Previous
evidence has been presented to suggest that human perception of the Hum can
involve multiple mechanisms. In the
author’s previous publications he has referred to one instance of which the Hum
in Bangor seemed to manifest magnetically.
More recently other similar instances have been noted. It seems that there is a ‘magnetic’ polarity
associated with the Hum and that sleeping in a certain direction can either enhance
or reduce its intensity. This is not thought to relate to acoustic directivity
since 27dB attenuating wax ear plugs were in use at the time.
A
possibly hypothesis here is that CP induced magnetic field may be either
counter to or reinforced with the earth’s natural field and Schuman resonance
signals. Associations between the Hum
and the IMF have been reported previously [26]. It is hoped to report more extensively on
this phenomenon at a later date.
Discussion and Further work
Examples
of severe corrosion have been noted with incorrectly installed gas meters.
Here
metallic structures have the potential to short out the ‘CP’.
It
is instructive to note that gas meter inputs and the house gas piping
connection are in effect electrically isolated from each other and have to be so
because of the use of active CP
[http://phmsa.dot.gov/pv_obj_cache/pv_obj_id_FE0D2DB95F943A92A45D7C084C4B07CAABC01200/filename/smalllpgas-chapt8.pdf
. An experiment could be conducted at
premises which experience the Hum to effectively ground the CP signal and note
any changes in the Hum. Any observed
changes whatsoever would be in strong support of the present hypothesis.
It
is quite feasible as a facet of evolution or environmental exposure that Humans
may be becoming more magnetically sensitive. This could either be due to
constant or intermittent exposure to RF which can re-organise metal ions and
metallic nanoparticles within the body [27]. Alternatively and/or additionally, the supply
of environmental metallic Nano-particles in our environment is increasing due
to industry, road use and aviation use [28].
This
magnetic sensitivity may be responsible for the link between two apparently at
first sight very different but potentially related manifestations of Hum like
phenomena. Because the Hum is highly
subjective and because once Infrasound/(magnetic) ELF sensitivity has developed
it is hard to shake it becomes possible for Hum like effects to become
perceived in unlikely scenarios. Thus
some subjects can perceive the
traditional Hum as strongly suggested to be associated with gas and electricity
infrastructure whereas others can additionally perceive a Hum in motor vehicles
parked at critically very specific distances
from certain digital transmitting antennas and thought to be associated
with the imparting of modulation information directly by magnetic vector
potential.
Conclusions
Active
corrosion protection and associated pipeline
test protocols are potentially a new and hitherto undisclosed possible feature in Britain’s Low Frequency
Noise (LFN) Phenomenon more commonly known as the Hum and such systems and
protocols may have the potential to amplify and increases noises from buried
infrastructure giving us an unusual and uncontemplated loudspeaker from the
tarmac underworld! An experimental
laboratory system albeit based simply on electrolyte solution produced some
20dB of acoustic gain more than sufficient to make a inaudible Hum audible,
although the frequencies were not those of the Hum appropriate scaling to the
roadside situation is suggestive that such frequencies known to be present
could be amplified. Moreover CP may
induce weak time varying magnetic fields comparable with the earth’s natural
field to which we humans are presumably
sub consciously attuned, particularly with respect to Schumann
resonance. A combination of infrasonic
and low frequency acoustic field together with a coherent magnetic field
appears to be the set of conditions required to generate the most pervasive
Hum. Such a set of conditions may have
inadvertently been introduced in the UK from the early 1970’s onwards as a
result of utility infrastructure changes.
It
would be very instructive to
interview a large number of a Hum
hearers and establish if they live near installations wherein active CP is used. Although the Hum has become far more
prevalent in recent years and seems to correlate with renewable energy I can’t
help but wonder if our tarmac underworld
were not now full of DC and
pulsed DC currents in addition to phase imbalanced AC currents perhaps we may never have had the Hum?
Acknowledgments
I
am grateful to the unnamed employees of
Wales and the West Utilities whom I interviewed regarding system pulsations. I
am grateful to an unknown CP survey team I recently interviewed. I am grateful to my wife Gwyneth for valuable
support and discussions during the preparation of this work.
References
1.
http://www.bbc.co.uk/news/magazine-13752688
2.
Mullins
and Kelly 1995 http://acousticalsociety.org/sites/default/files/docs/echoes/v5n3.pdf
3.
http://www.drchrisbarnes.co.uk/lfnhum.htm
4.
http://www.johndawes.pwp.blueyonder.co.uk/
5.
(Poulsen and Mortensen Working Report 1 to Danish
Environmental Protection Agency 2002).
7.
https://groups.google.com/forum/#!forum/hum-sufferers
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http://www.drchrisbarnes.co.uk/UTILITY.htm
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14. http://www.drchrisbarnes.co.uk/HUMCAVE.htm
15. https://en.wikipedia.org/wiki/Cathodic_protection
16. http://www.open-grid-europe.com/cps/rde/oge-internet/hs.xsl/Korrosionsschutz-fur-Pipelines-Verdichter-und-Pumpstationen-sowie-Industrieanlagen-1467.htm?rdeLocaleAttr=en&rdeCOQ=SID-B7255218-4C498EB5
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19. repository.tudelft.nl/assets/uuid:520eb85c-6f74.../Koleva_2006.pdf
20. http://www.drchrisbarnes.co.uk/UTILITY.htm
21. http://www.sciencedirect.com/science/article/pii/0003682X7790007X
23. http://www.documentation.emersonprocess.com/groups/public/documents/reference/d351798x012_05.pdfhttp://www.documentation.emersonprocess.com/groups/public/documents/reference/d351798x012_05.pdf
24. http://www.sciencedirect.com/science/article/pii/S0307904X06002915
25. http://www.drchrisbarnes.co.uk/BANGORhum.htm
26. http://www.drchrisbarnes.co.uk/HUMIMF.html
27. http://www.sciencedirect.com/science/article/pii/S0039606010002266
28. http://www.nanocap.eu/Flex/Site/Download047b.pdf?ID=4445