Low Frequency Magnetic Studies of Hums in Wales, UK personal observations and first hand anecdotal experience dependence on time evolution of frequency spectrum in the range 0-250 Hz. By Dr C. Barnes August 2011 scienceconsultants@yahoo.co.uk

Abstract

Magnetic spectra have been recorded in the frequency range 0-250 Hz at various locations which always experience the Hum and at the author's home which sporadically experiences the Hum. Requisites in the spectra for the Hum are either frequency modulation on the 50 Hz component of the mains and/or the presence of a magnetic comb spectrum from about 4 Hz upwards. In the 50 Hz case, since infrasonic and acoustic signals (sub, inter and integer harmonics) are always present which mirror most if not quite all the magnetic frequencies it is not thought necessary to invoke any special bio-magnetic audition process for perception of the Hum and indeed it was not possible to prove one under laboratory conditions either. However in the case of comb spectra arising from mobile telephony bio-detection may also feature.

Introduction

Aside from the Internet self-publications of the present author, the Internet site of private Hum researcher John Dawes in Bristol UK, the Site of Dr Tom Moir in New Zealand  and published studies of the two most well known hums in the USA, namely Kokomo and Taos, there are only three peer reviewed published articles on the Hum in recent years, hardly surprising in that the Hum is a very subjective phenomenon   only heard or experienced by about 6% of the adult population mainly but not exclusively in the 50-60 age group.  Firstly was the paper by Deming¹   in the Journal of Scientific Exploration wherein the most probable but by no means certain cause of the Hum in time and space was identified as electromagnetic emissions from a certain type of military aircraft. Next came the letter to the editor in reply by the present author² suggesting infrasound as a more likely cause of the Hum and further suggesting that if the human body is an electromagnetic detector of the Hum the detection would have to be quantised ( coherent) in some way otherwise all electromagnetic frequencies would be heard. Finally we have the paper given by Cowan at the ICBEN Congress in 2008³  which acknowledges that in many cases Hums are actually traceable to low frequency sounds (and infrasound) such as emissions from factories and industrial sites but also cites the number of unexplained cases of the Hum of the type that cannot readily be blocked by ear plugs evidenced in both the Kokomo and Taos Hum studies and further goes on to expose a first common thread  at all these Hum  locations namely high alternating magnetic field strengths in the region 3-50 milli-gauss. Cowan then mentions a second equally important common thread which is that many respondents in the US Hum studies reported the Hum started after utility companies made changes to external electricity or telephone wiring or upon the erection of new cell phone towers etc.   Clearly although electricity distribution and telephone circuits work at similar frequencies, those of cell phone towers are very different and we need to search for a common thread.  One possibility is mentioned in the Kokomo Hum study that is radio frequency signals being carried by or modulated onto the mains frequency.  The Hum has been heard in several locations in Britain since the 1970's and the number of locations  where it heard seem to be expanding. Although the US is much larger than Britain the number of high profile Hum reports seems less. Dawes has ascribed causality of the Hum to the power generation and distribution industry. It is interesting to note that until July 2011 the US had far more stringent regulations on Power Grid frequency control than the UK, allowing only +- 0.02 Hz derivation as opposed to +/-0.5 Hz deviation. The US figure has simply not been sustainable with the the advent of Low Carbon Energy. With the relaxation of frequency control in the US it will be interesting to see if more Hum cases are reported there. The Russian Power Grid prides itself on being frequency accurate bang on 50 Hz an amazing 99.9% of the time. There have been few if any Hum reports arising out of Russia. Since 2007 China has reported problems with low frequency oscillations on some of its power grids http://www.energo-info.ru/images/pdf/Rele/Session_4/S4-3.pdf. At the time of writing it is not known if there are any specific Hum reports from China but Hum information websites have more recently been accessed form China. Australia and New Zealand' s power grid specifications are similar to the UK and there are reports of the Hum from both countries. Japan has a dual frequency supply 50/60Hz with frequency converters and since the scale 9 EQ controls its power demand by rolling black outs. It has not been possible to find data on frequency stability. It is know however that Japan has almost exclusively gas insulated transformers notoriously good for sound vibration isolation.

Returning to Cowan, clearly he also states the ultimate goal is to try and find methods of relief for individuals plagued by the Hum.  Cowan also reaches a conclusion that electromagnetic signals at the power levels observed in the two US studies may be being detectable at places in the human body other than be the ear. Whilst the present author does not necessarily accept such a contention outright and has previously presented an explanation of how low level microwaves could resonate in the ear depending on the precise physical dimension of its various components⁴, it remains a distinct possibility for low frequency magnetic stimulation.  Alternatively, we need to see if the frequencies detected magnetically also appear in the acoustic environment, bearing in mind that we have far more sensitive tools of acoustic measurement these days than were available during the Taos and Kokomo studies.      

Ironically the Hum is doubtless one of the most complex present day paradoxes in Science yet it is perhaps the least officially researched.  Only when we fully understand this tantalising electro-acoustic phenomenon will we be able to devise methods of relief for its sufferers.    

This present paper presents the results of a series of experiments which finally start to bring together all the loose ends in Hum research. Although the study is made in the UK there is no reason why it shouldn’t have relevance to the rest of the World although of course the frequencies of generated electricity do vary from country to country.        

Experimental Apparatus and Materials

A home made alternating field gauss meter was constructed and calibrated against known 50 Hz sources. This was used to obtain the magnetic field strength at various locations both in the field and at the author’s residence. In the frequency time evolution experiments the search coil form the gauss meter was connected to the line in jack of a Dell laptop computer running a piece of spectrum analysis software known as Spectrum Lab.  Although designed primarily for the Ham Radio market this is an incredibly powerful and versatile program.

Experimental Procedure        

Four in the field locations were visited, three of which had been shown in previous locations to elicit experience of the Hum in both the author and his wife when seated in a parked motor vehicle. More specifically the locations which had previously been observed to elicit Hum were, as defined by Ordnance Survey Grid Co-ordinates; firstly  Minfford Hospital (closed) SH579710 which is within 100 metres of a multi-user GSM, UTMS  and TETRA transmitting mast at least 40 metres in height and also containing several point to point microwave backhaul links, secondly  SH59861 Tregarth Church, and finally, SH619696 which lies immediately underneath National Grid ‘Supergrid’ electricity transmission lines. The fourth in field location was at

SH 607702 on the outskirts of Tal-y- Bont near Bangor. Interestingly, some two years or so ago this location did not elicit the Hum, now it does.  Careful investigation of the surrounding countryside reveals a new mobile phone mast located nearby at SH609713 not yet marked on ‘Sitefinder’ website.   

Measurements were also made at the author’s home a place where the Hum is physically heard to turn on and off at various times and is mainly on during the night and has been previously ascribed as potentially being due to infrasound emissions from the  Dinorwig pumped  storage hydro-electricity plant.

The ac magnetic field in milli-gauss was recorded for each location as was the time evolved magnetic frequency spectrum in the range 0- 250 Hz.       

Experimental Results

The ac magnetic field at the entire in field locations with the exception of the one directly underneath the high voltage transmission lines was almost a constant 1 milli-gauss. At SH619696 the field was 18 milli-gauss inside the vehicle! At this location the Hum could be heard most strongly.  At the author’s home, the field was also of the order of 1 milli-gauss irrespective of the presence of the Hum.

The time evolved frequency spectra varied considerably across all the sites. The key salient points have been recorded in figure1.   

Figure 1; Results of time evolved frequency spectra for various locations.

In the table the following key is used. P = Pulses. PFM = Frequcny changing in a pulse like manner. PAM = Amplitude changing in a pulse like manner.             CONST = Frequency and amplitude constant. MISS= Frequency missing.   WEAK = signal or Hum weak. PRES = Signal present. STRONG = Signal strong. COMB = Electromagnetic Comb Spectrum spreading every few Hz from 20-250 Hz.  RFM = random walk frequency shift.

Discussion of the Results

The computer stored frequency- time traces generated in this study are available

If requested to be viewed by any of the readership however they are so complex and would all need to be viewed simultaneously rather than sequentially as on a printed page to fully appreciate the salient information therein which has thus been transferred to the table figure 1. Even this, at fist sight, looks rather complex and overwhelming to meaningfully interpret. Indeed upon close inspection it is easier to see what in the frequency spectrum the Hum doesn’t cause than what it does!  The answer appears to be that at any site or time when the 50 Hz magnetic component of mains frequency is constant or near constant in amplitude and frequency and with few if any harmonics present there will be expected to be no Hum.   

On the other hand and irrespective of magnetic field strength in the range 1-18 mG the Hum was experienced by the author and his wife at sites which had either a magnetic comb spectrum (the author has reported on this elsewhere⁴) or which have either random walk or pulse frequency modulation superimposed on the 50 Hz component of the mains i.e. locations wherein for whatever reason the electricity supply has either poor frequency regulation or is perhaps under some sort of forced or active frequency control.   At the author’s home the Hum seemed subjectively worse when the 250 Hz harmonic got stronger and started to display amplitude pulsations.   All the locations displayed broad magnetic noise in the range 0-20 Hz the origin of which is unclear, but may either be geological in origin or because there is so much mobile telephony in the area?        

Of further interest is that at the authors’ home address almost all the frequencies recorded by the magnetic pick up coil could also be recorded by the laptop microphone with the exception of the 150 and 250 Hz components.  Either most of the frequencies were also in the acoustic environment of the house or the electric field component of the frequencies was strong enough to swamp the laptop electret’s input. In the former case the present author has made suggestions in the past regarding transduction of audio and infrasonic frequencies by house walls⁵ . Further in this regard the bricks or roack of a house wall or the soil and rock on which it stands may act to a certain extent as a porous medium which can take on various levels of fluid saturation . It is known from studies of geological prospecting methods that two-way electro acoustic interactions can take place under such conditions ( Hu et al JASA 122 (1) pp 135-145, 2007 ).

Similarly, acoustic and infrasonic frequencies have been recorded in the author’s vehicle at Hum locations in the field. It is conceivable that, particularly when parked underneath high voltage power lines, sufficient eddy current may flow in the car body to generate sound by both Lorentz forces and magnetostriction.   Similar currents may flow in the ring mains of house wiring or in central heating systems irrespective of whether or not the house the house electricity supply is turned on. Alternatively geological electro acoustic interactions may set up ground vibrations transmittable into the vehicle. It should be stressed that in order to make such measurements in a modern motor vehicle on must wait several tens of seconds after switching off the engine and removing the ignition key and one must make sure the security systems are disarmed  otherwise false magnetic spectra may be recorded, the author has commented on this elsewhere.    

 Of course at just one of the sites the comb spectra arose from mobile telephony and here the author believes that bio-detection may also feature.

Such bio-detection is also thought to be relevant at specific distances from such sites ( Barnes ref).

Theory deriving from the results explaining the annoyance of the Hum 

Irrespective of the mechanism for magnetic hearing or whether we even need to invoke one at all  http://science.nasa.gov/science-news/science-at-nasa/2001/ast26nov_1/ it is evident that the Hum is only perceived by the two subjects of the present study when either a magnetic comb spectrum is present or when alternating frequency sweeping of the 50 Hz component takes place be it random or more regularly pulsed. In classical hearing, it is well known that a pure tone is subjectively more annoying than a noise like wind or waves (ref) because it calls for attention.  However, a pure tone is far easier to ignore than a frequency sweep (ref). Such frequency sweeps were present in random or pulsed format on the 50 Hz magnetic component of all the Hum sites.  The comb spectra present near the multi-user radio mast will effectively be turning on and off with very fast pulse rise and fall times and to some extent mirror the effect of frequency sweep especially if the magnetic hearing process has latency the same way in which classical hearing does. In any event a survey recently found pulsing noises to be more annoying than continuous noise http://www.theplymouthstudentscientist.org.uk/index.php/educator/article/viewFile/96/144; thus, it easy to see why both the above conditions elicit annoyance in some individuals who perceive the Hum.  

If acoustic sound and infrasound is present in addition to the magnetic frequency components and has a constant phase relationship or coherence with them then there is double the opportunity or possibly worse for eliciting the annoyance. Synasthesia or duelling of the senses here is a real possibility. Further duelling of senses may be possible if the magnetic components are reflected in the spectral behaviour of street lighting for instance it has recently been shown that there is more of a link between audition and vision than previously understood (ref).  If microwaves are present there is the possibility for thermo-acoustic or dielectric resonance absorption by the ear in addition to classical hearing and low frequency magnetic processes.   A frequency of 55 Hz was also recorded at the home of the author. It is not known whether this significantly contributes to the Hum and its origin is also unclear but its magnitude was on a par with the 50 Hz component of the mains frequency!  It is interesting to note that Dr Tom Moir recorded a frequency of 56 Hz in New Zealand allegedly associated with the Auckland or North Shore Hum.  Such frequencies can be generated as a result of inter-harmonics in the electrical power distribution industry particularly when loads include arc furnaces and cyclo-converters ( EW Gunther IEEE July 2001) and (Salor et al IEEE Trans Industrial Applications Vol 46 2010 pp60-80).

Re-visiting the Bangor Hum

The magnetic observations in this present paper add a new dimension to the Bangor Hum. Here is a Hum ascribed by the author to originate from the Dinorwig pumped storage hydro-plant  which is observed by afflicted individuals to switch on and off at different time of the day and night and is evidence by the appearance of specific infrasound frequencies and now it would appear also specific changes in the low frequency magnetic environment.  Even a lay person can hypothesise the   two are almost certainly related. In the day the system is used for frequency control of the National Grid whereas at night it uses cheap electricity to pump water back up the mountain, wherein frequency control will not be possible.  Power line harmonics are known to radiate greater distance at night    http://docs.google.com/viewer?a=v&q=cache:oadlGMAdk_4J:sgodata.sgo.fi/pub/Jyrki/VLFabstracts/Werner1.doc+when+more+harmonic+radiation+from+power+grid&hl=en&gl=uk&pid=bl&srcid=ADGEEShecfU_c0WqjF-S3V5h3fMxKEUHuPIfgeWIzdYYAXZw5ClBmMnhu5ul12BMYXqoS4wh4upZjF5R04L3-M2940MFh6Vew5ttUKisfqLYyOurbeOsFfdRSRXwaIanv7BdR4Prvt_W&sig=AHIEtbQpgDaJfXowjkpD3Wll3OXPIpiA9g

And this too is consistent with the author’s observations. Other sources of frequency variations and harmonics on power lines will be wind turbine inverters and individuals with solar energy systems. Non-linear loads such as cyclo power converters for high energy Physics experiments and the like also play a significant part.   All will be expected to add to the Hum in future.  The situation is further complicated because we could have direct ground borne and airborne infra sound transmission from the turbines and geophysically generated infra sound from the power grid itself ( US PATENT 7,227,362, B2)  The Hum mainly afflicts people in their 50’s who would have been born into an environment where the ac mains frequency was a much cleaner  50 Hz  than it is today, maybe they evolved to be able to screen out this component but not others. Time will tell if in thirty years time today’s twenty years olds also experience the Hum and if so how will they describe it?  

Towards a magnetic hypothesis

Many ‘hummers’ report only perceiving the Hum indoors or inside a vehicle. Indeed the present author has only ever heard the Hum outside twice. It is easy to see how an infrasonic Hum could be boosted by room reverberation and resonance and this has been dealt with elsewhere (ref). The steering gear and suspension of cars have low frequency resonances (refs) and it is vaguely possible to see how these could be driven be an external seismic Hum or ground vibration such as also for example those thought to originate from gas distribution systems (ref) but there is insufficient air volume to drive resonance much below 200Hz (ref) in most vehicles to support the higher frequency reported components of reported hums.         

One possible conclusion is thus Hums of non-magnetic origin are more likely to be heard in houses whereas Hums of magnetic origin are equally likely to be perceived in houses or cars.       

 It has been shown above and elsewhere (ref) that most of the frequency components found in magnetic spectra at Hum locations are also present in the acoustic spectra. Mechanisms for conversion have been put forward (Barnes refs). So maybe we don’t need a bio-magnetic mechanism for Hum transduction after all!   There can be some possible criticism levelled here in that there are essentially only two types of acousto-electric transducer available for acoustic recording; namely electromagnetic (dynamic moving coil microphone) and piezo-electric (either permanently poled or non-permanently poled as in electrets.)   Thus in addition to recording sound, a dynamic microphone could theoretically also respond to magnetic signals and electrets could respond to electric fields.   However such transducers have positively identified non-magnetic Hum sources in Kokomo thus the distinction remains in tact.

 However, the fact remains that some Hums in some places have not been recordable by conventional equipment. In the author's opinion it could simply be that the equipment was not sensitive enough or it could be that the Hum is still acoustic in some way but is perceived by internal beats between frequencies in some other part of the spectrum.  Or finally, we have to consider bio-magnetic mechanisms.  Some hummers describe the Hum as so bad it cannot be screened out by ear plugs. Infrasound is course difficult to screen by ear plugs and in this respect the advice to Hummers that wax plugs are far more attenuating at low frequencies than foam ones. 

The present author believes that such an intense, un-screenable Hum cannot be a fallacy as he once experienced it himself at his home location.   In this case the Hum was so intense ear plugs did not work at all and this coincided with the recording of a magnetic comb spectrum with a signal every 4 Hz or so between 4- circa 300 Hz. The author has only ever once recorded such a signal at his home location.  In this respect the signal was so unlike the one recorded with a few tens of feet of the multi-user radio and microwave site described above. To understand the transduction of such a signal we will have to invoke a bio-magnetic hypothesis where at the very least the outer ear is excluded or may be the entire auditory apparatus is excluded as Cowan³    has suggested.

Humans have evolved in weak static and alternating magnetic fields due to the polarity of the earth and due to Schumann resonances since the dawn of time. There are theories that the whole of life itself is electromagnetically mediated (ref).

By employing enormous magnetic fields, a sort of shear brute force and ignorance method, one can cause nerve stimulation deep in the brain. This is an experimental psychiatric procedure known as trans-cranial magnetic stimulation meant to be a gentler alternative to so called electric convulsion therapy .  Interestingly, TMS has recently been shown to be of some benefit to tinnitus sufferers. However, the fields involved are 1000’s of gauss about a million times greater than the fields associated with the Hum.

Although the Earth’s   static field is about 4000 milli-guass the time varying field amplitudes associated with Schumann resonance are about 10^-4      milli-gauss and some would say the fields associated with electricity use and generation way overwhelm this. In this respect it is interesting to note that the Amish a tribe who for religious reasons don’t use electricity or electrical appliances don’t suffer from conditions like ADHD or multiple allergy syndromes. Smith   has recently made tremendous leaps in the allergy and homoeopathy areas and has shown magnetic quantised water memory effects (ref).  

It has been suggested that the body or at least living cells could act as coherent receptors of electromagnetic radiation (refs) and one such mechanism in particular gives rise to a range of frequencies which would encompass Schumann resonance (ref) and hence also those reported to be associated with the Hum. The theory is not specific as to which type of cell but simply deals with the way in which electromagnetic waves could perturb protein mediated ion transport. Thus bio-magnetic detection could take place either in the cells of the cochlea or in the auditory nerve or elsewhere. It has been cited that the optic nerve is a possible route for magnetic detection (refs).  

 Testing the magnetic hypothesis

A series of experiments were carried out using two separate transducer coils one solenoid and one toroid. Each produced a maximum field of 7 mG when driven by an audio power amplifier. Several series of waveforms were applied in order to try and simulate those experienced at Hum locations.

Under none of the experimental circumstances was it possible to discern Hum like effects in the vicinity of either coil.

This result suggests that direct bio- magnetic hearing at least in the lower part of the field range mentioned by Cowan might not be possible. Of course in the field we were dealing with signals coming from multiple sources and with the spectrum analyzer software and waterfall display it was not possible to determine the phase relationship between them which could be crucial in the bio-detection process.

It should also be stressed that this study only followed magnetic signals up to 250 Hz. It is possible that higher harmonics of the mains frequency may be involved in the Hum, they certainly influence space weather ( Nemec et al Journal of Geophysical Research vol 112, 2007 ). Possibly the body has a system for responding to ionosphere generated LES or ion acoustic waves similar to the infra sound from Auroras (Procunier, Geophysical journals OF THE Royal Astronomical Society, Vol 26, 1971).

What is certain is that further significant investigation will be required in this area if remedies are to be found to bring relief to those afflicted by the Hum. During the time of writing, the present author certainly has some interesting ideas but will test and more than likely patent these before making a disclosure.               

Conclusions

• Magnetic signals have been recorded at Hum sites

• The main signal factor which often seems to be recorded when the Hum is perceived by the two subjects in this present study is frequency modulation appearing on the 50 Hz magnetic component of the mains and the presence of higher harmonics 

• Or the presence of a magnetic comb spectrum, such spectra can appear as a result of mobile telephony where a separate bio-dection mechanism may feature..

• A dependency  on alternating magnetic field strength has not been established although the Hum was subjectively worse at 18 milli-gauss than 1 Milli-gauss but underneath the  power transmission line there was effectively a comb spectrum present as well as some FM component  

• Most of the power systems associated magnetic signals also appear as infrasonic and acoustic signals at whatever location  

• Only on one occasion in some 7 years of perceiving the Hum would the author have perceived a Hum so intensive and un-screenable that there would be the need to invoke a wholly bio-magnetic mechanism for its perception.

• With the exception of the above instance, the Hum in the author’s locality can now be fully explained in terms of infrasonic signals from the Dinorwig hydro-power plant and coincident (possibly coherent) effect on the local magnetic spectrum generated at least in part by changes to the waveform of mains electricity.   

• A frequency of 55 Hz has been recorded a similar frequency of 56 Hz was recorded by Dr Tom Moir in New Zealand, these are very probably power system inter-harmonics. .

• As suggested by Hum investigator John Dawes some cases of the Hum are most certainly associated with the electricity supply industry

• The author was unable to prove the existence low frequency bio-detection using laboratory signals and apparatus with magnetic fields in the range 0-7 milli-gauss.

• The above does not rule out possibilities involving ionosphere perturbation at KHz frequencies and/or infrasonic as been possibly related to the Hum.

• The author is now making further investigations particularity striving to produce a remedy for those afflicted by the Hum.