Home » Uncategorized » A guest post from Henrik: electronics engineer and radio specialist

A guest post from Henrik: electronics engineer and radio specialist

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Henrik has serious credentials in several fields that connect directly with investigations into the Hum. I asked him to produce a short paper for us, summarizing his thinking. This is his response, and it is an excellent piece:

By: Henrik

Drawing on what we know

I have followed this blog for over a year, but since I am not a Hum-hearer myself, I have been reluctant to comment. However, I am an electrical and electronics engineer with radio transmission as my specialty, and have looked at infrasound in relation to wind power plants, so here is my two cents worth:

  1. From the hundreds of contributions to this blog, I would draw the conclusion that there must be at least two different root causes of the Hum. One source must be real mechanical vibrations or low-frequency sounds or infrasounds, carried through the ground or through the air. The other must be a change to the Hum hearer’s auditory organs or brain chemistry, so that he/she in certain circumstances perceives a sound/hum without a physical sound existing outside the body.
  2. In both cases, we must answer the question, why only 2-4% of the general population hears the Hum, while most other people around , even in the same time and place, do not experience anything. This is also the only avenue to ever finding a remedy to the problem(s).
  3. In the case of vibrations and low-frequency or infrasounds, the Hum hearers must have been sensitized by something so they have a much lower hearing or sensing threshold than the average person. This is called hyperacusis, and can be caused by, among other things, certain medications and head traumas. Benzodiazepines and other stress relievers are known to cause hyperacusis in sensitive individuals, but many other medicines also have a long list of rare side effects if taken over longer periods or in high doses. Additionally, some people just naturally have a lower hearing threshold for low frequencies. The so-called A-weighted sound pressure curves relate to what we hear through the ear drums. For infrasounds the ear drums (and the A-curve) are irrelevant, since the whole head and the body become the much bigger receiving “antenna” for the vibrations. This means that the inner auditory organs are simply “shaken” together with the whole head, and we can “hear”, or rather feel, things, which the ear drums are too small to register. That is why earplugs are useless to stop the health problems from infrasound near wind power plants.
  4. Additionally, certain atmospheric conditions (ducting through the formation of inversion layers) can amplify distant low-frequency noises. Room resonances can cause standing waves and amplify certain frequencies, so that the sound is heard stronger in certain points in a room. A closed space can also resonate in Helmholtz mode through ventilation ducts or other narrow passages.
  5. For the case of internally generated “sound” (otoacoustic sounds), the explanations become more complicated, when we need to explain why only a few % hear the Hum. We need to find out what has caused the auditory organs of the Hum hearers to start producing the Hum, and what external factors trigger it and affect how strong it is heard. Many observations mention seasonal changes in weather. There is a hypothesis that long-term exposure to radio frequencies could cause hyperacusis but I have not yet seen any sources that would tie RF exposure to otoacoustics.
  6. From what I know about radio technology, I have difficulties in buying the idea that an EMF field of any frequency would directly cause certain individuals to hear the Hum. My reasoning is that the field strength of any electromagnetic field of any frequency (even 50 or 60 Hz) diminishes with the square of the distance. If we move from a place 100m from a radio transmitter or power line to around 3km away, the field strength has been reduced by a factor of approximately 1000. This means that there would have to exist certain “hot spots” near such EMF sources, where everybody would hear the Hum. It is impossible that one individual would be a thousand or one million times more sensitive to the EMF than another. Such hot spots do not exist. Ergo: Direct EMF influence cannot cause the Hum.
  7. The susceptibility for suffering from otoacoustic Hum must in my opinion be a result either of spontaneous biological changes, stress factors, other environmental influences, nutrition, nutritional supplements, or medications. It appears not to be an age-related degenerative phenomenon, since old people are much less affected by the Hum. Real-time environmental factors like weather, time of the day, stress level, or internal factors like blood sugar level, blood pressure, electrolyte balance, fatigue, etc. may then determine when it is triggered and how strongly it is perceived.

Hopefully this kind of structured thinking could help some Hum hearers to get a grip of what has made them Hum hearers and/or what could be the root cause of their experiences. Try to rethink your own observations using these logical filters, and see if you come up with some new thoughts about your own experience. I would especially like to suggest that you try recall whether any longer-term medication or major change in your physical environment or stress level would match the time you started to hear the Hum.





  1. Janet Menage says:

    Thank you. I was very interested to hear the bit about earplugs being useless as regards infrasound from wind turbines. The whole-body resonance is certainly what I feel with the Hum (although high-density earplugs do reduce the actual noise level by about half).
    In terms of people’s sensitivity to the Hum, I am reminded of an experiment that my (grown up) children did with me. They played a high frequency sound on their mobile phones & said that older people wouldn’t be able to hear it due to otosclerosis. They could both hear it but I couldn’t. Years later I can hear the Hum but they can’t! (Although my 30 year old daughter did experience a feeling of pressure in her ears & head in my house recently and she asked if I’d left the central heating on all night as she’d heard what sounded like a CH pump).
    You said that age is not a factor in who can hear the Hum, but maybe some people’s auditory range shifts downwards from higher to lower frequencies, for some reason. It would be interesting to get one’s range mapped with an audiometer (assuming that such equipment goes into the infrasound range).
    It must be remembered that acoustic neuroma and brain cancer have been linked to the use of mobile phones in contact with the ear/head (& not just due to the heating effect). So it may be premature to dismiss EMF as a contributing factor – perhaps as a sensitiser of some kind.

    • Henrik says:

      I agree. EMF can well be a sensitizer, but the mechanism/physiology of that is beyond my knowledge. What I claim is that the hum is not caused by any momentary/simultaneous EMF when the hum is heard..

  2. Ann Ferguson says:

    You say that unlikely to be EMF but our TV screen often pixilates when the him starts or changes in intensity. Does this not imply a relationship with the electro magnetic field?

    • Henrik says:

      The TV screen pixelates when the TV signal experiences some fading so it comes close to the receiver threshold. Fading comes from atmospheric anomalities, not EMF. If the pixelation and the hum happen really instantly, like within seconds of each other, it may be caused by fluctuations in the electric grid, possibly becasue some big electric motor is starting. Then what you hear can be that machine. I don’t see any relation to any EMF here.

      • Ann Ferguson says:

        I first heard the hum in 2006 and have heard it regularly since. At first I thought it was a lorry with engine running outside our cottage in deepest rural Northhumberland. Obviously there was no lorry!
        This hum hearing coincided with the opening of a windfarm in the Scottish Borders some miles away so I wondered if that could be the cause. The noise I hear is not continuous and there are times when I cannot hear it at all and fluctuates in volume. In fact an engineer from Ofcom came and was able to record the sound but had no explanation for it. I have since moved into an area several miles from our original cottage which is nearer power lines and pylons and another wind farm. So, my question is this, could the noise I hear and the TV pixilation have anything to do with wind turbines connecting to the grid especially as the sound can be louder at night when wind turbines are allowed to produce more noise? Yes I do take medication, candisartan for high blood pressure and bendroflumathiazide, plus ventoline. The first two I have taken for many years long before I heard the hum. Whatever I am hearing I do not believe for one minute that it has anything to do with my health but an external physical phenomenon.

  3. Jennifer Webster says:

    I don’t feel pressure in my ears. I can hear a sound AND I also feel the vibration of the sound. Some days I do not hear the HUM at all – usually when it is a lovely sunny day and no clouds.

    • Henrik says:

      I would suggest you check out if you have any wind power plants within 3-5 miles, or some industrial complex. Heart palpitations (arrythmia) can also easily be felt as a “vibration”. But I am no doctor…

  4. David says:

    Hello Henrik, thank you for taking the time to make an interest in the Hum. For you a non Hum sufferer I appreciate it and I hope more people take an interest.

    Im a Hum tone sufferer. I have been since 2012. A brain injury survivor from 1998. I cant see how 14 years later a head trauma has led to me to now hear the Hum. Im no more stressed than the average man.

    I dont believe the Hum is generated internally as when I block my hearing or leave an area I hear the Hum I no longer hear it.

    David in Ireland.

    • Henrik says:

      Your case sounds like an actual audio hum. Check out your environment for wind power plants or generators or big ventilation systems for commercial buildings.

      • Ann Ferguson says:

        There were another 2 people in the area could hear it because we played them the recording. One was an old sheperd who thought it came from a potato store and drier at least 5 miles away, the other was a fellow in his late 40′ s who had heard it for some time and reckoned it had something to do with the military exercises which took place in the area, e.g. fighter jets.

      • David says:

        Yep none of those are the culprits as I can hear the Hum in rural Ireland with no wind power plants etc. around the area. Though I would not rule out that theory completely if wind turbines can transmit audio/the hum through vast distances.

      • Janet Menage says:

        The only problem with the wind turbine theory is that I can hear the Hum all the time, even when there’s no wind and the turbines are stationary. Also, if several wind turbines were contributing their noise/vibration/infrasound, surely there would be in-phase and out-of-phase elements, ie. they would interfere with each other, so you’d get a ‘beating’ effect, or, at least, a less homogeneous sound?

  5. Henrik says:

    Ann Ferguson: If the sound you hear could be recorded, you have an actual environmental noise source somewhere. The wind farms would be the first on my suspects’ list. Try on a windy day to go 5 miles or more away and check if there is any difference. You may have a mild case of hyperacusis, if other people do not hear anything.

  6. Henrik –

    I think we agree that there are both real acoustic vibrations (peripheral and relatively easy to address) and afflictions where there is no acoustic counterpart in the environment. My main interest is in the case of 24/7/365 occurrence of the Hum (that is – always – when background noise does not mask) that moves over unlimited distance with the hearer. I have heard this Hum for almost 20 years.

    Two important characteristics for which I would value your comments are:

    (1) The Hum has never been recorded. Of course if there is a truck outside your window you can both hear, and record it. The interesting case is where you hear the Hum and can’t record it. I have done this experiment:


    What I did was amplify, notch out 60 and 120 Hz, and look for the residue. I heard the Hum, but did not see anything except random noise. Inserting a real (acoustic) signal, I both heard and saw it. Many details in the report.

    (2) Very soon after my first hearing 20 years ago, I discovered that I could interrupt the Hum, for only about 1/2 sec, by head shaking or a short grunt. This told me that it was NOT an external source. Other hearers agree, and this too I have written up:


    All this and more arguing for an internal (otoacoustic) source is reviewed in a less technical report here:


    I am not clear what explanation you most favor, but would be interested in how your ideas address the non-existence of an external acoustical component and the interruptions.


    • Henrik says:

      I agree that we have two totally distinct cases; real environmental hum or other noise sources, which some sensitive people hear/feel while others don’t, and then the real World Hum, which is still a mystery.
      In your individual case you made a recording of something that anyway was not what you heard. I think it was a flaw to use a loudspeaker as microphone, because that picked up also any vibrations from the structure/building and converted them to audio. Mechanical/seismic vibrations can be carried for tens of miles through the ground, much more efficiently than through air. What I saw in your notch-filtered graphs was ground vibrations plus sub-harmonics and standing waves from the power grid. A battery-powered test setup with a laboratory electret microphone (1Hz lower cutoff) hung in free space with long rubber bands would have eliminated most of those residues.
      Since I am not a hum hearer, I cannot really comment on your statement that your Hum can be interrupted by shaking your head or making a grunt, while outside audio would not be interrupted. The only I can comment on that is, that since all bodily senses are logarithmic, there is an built in nonlinearity (“AGC”) in all sensory organs, which could explain such an interruption, in analogy with transient overload in an amplifier. Medicine uses that in TENS for pain control, for example.
      So we are pretty much in agreement that the real Mystery Hum is otoacoustic, and that the key scope of this project is to try to find the sensitizers and triggers of this phenomenon. It is obvious that your own case is otoacoustic. But your 24/7/365 Hum seems to be atypical among the observations. For most Hum hearers it comes and goes.
      I also think that the basic “hum” experience must be described better by those who hear and suffer from it. To routinely call it “idling engine sound” is not enough. Anyone can create an “idling engine sound” by pushing a finger hard into each ear, or firmly cupping the hands over the ear lobes with suitable pressure. We need more intelligent descriptions than “idling engine”.

  7. Henrik – thanks for the comments.

    You said: “I think it was a flaw to use a loudspeaker as microphone, because that picked up also any vibrations from the structure/building and converted them to audio.”

    Well, that’s what I used 20 years ago, and what Mullins & Kelly used in 1995

    http://acousticalsociety.org/sites/default/files/docs/echoes/v5n3.pdf .

    If it picked up extra, what harm? I still see NOTHING coherent – I apologize if I misled by not explaining that the images were only typical of the noise. No sub-harmonics or anything periodic. Anyway, I tested the pickup of a real 50 Hz acoustical signal, room resonances, impulses (foot stomp) etc.:



    You mentioned AGC.

    Exactly – my impression 20 years ago and still today. The protection muscles relaxing (idling) and the clamping down for a half second in response to a transient.


    You said: “But your 24/7/365 Hum seems to be atypical among the observations. For most Hum hearers it comes and goes.”

    As I have said, my case is apparently mild, and comes-and-goes as I just ignore it most of the time. There has never been a time WHEN IT WAS QUIET ENOUGH when I couldn’t hear it by consciously trying.


    You said: “We need more intelligent descriptions than ‘idling engine’ ”.

    I can’t imagine why. Believe us – that’s what it sound like. I’ll bet 90% of hearers went out looking for a truck!

    – Bernie

  8. Ann Ferguson says:

    Yes Bernie that is what it sounds like although sometimes I hear it like the sound of beating helicopter blades. In fact I ask my husband if he can hear a helicopter and if he says no then I believe what I’m hearing is the hum.

  9. Henrik says:


    This relates to what I said about describing the Hum better. An otoacoustic sound, which is generated inside each individual’s head/brain cannot in any likelihood be exactly identical in appearance for everyone. I believe it could help some medical expertise to start pinpointing the root causes, if the Hum hearers could describe their individual experiences more accurately, so we could find the common denominators, which constitute the phenomenon we call The World Hum.

    For example, the sound of an idling engine is a pulsating sound of multiple low-frequency sounds generated by different parts of the engine. There have been reported some serious attempts at determining the frequency of the Hum by using an external tone generator, and if that is possible for some cases, that cannot sound like an idling engine, since we cannot generate a “beat” tone with a multi-frequency noise, which an engine actually represents.

    The “helicopter” sound, which Ann Ferguson mentions, is again typical for the acoustic noise caused by wind power farms, especially in the downwind direction, when the pressure spikes caused by the blades passing the pylon modulate the “purr” from the gearboxes. This phenomenon is of course not present in otoacoustic cases.

    So in short, I stand by my statement that we need more accurate descriptions if we shall get anywhere in solving this mystery.

  10. Henrik –
    (1) Actually, characterizing the Hum is a good part of what Glen has (heroically!) been doing for years. And it’s not easy. If you yourself heard it, you might well (as an EE) be able to characterize it. But even a room of 50 EE’s (with audio experience if you wish) is likely to have only one hearer. People in the general public can’t fathom a question you would want to ask – (not a criticism – why would they)? I think there are some excellent accounts by non-engineers on this site, and I always feel when I read one of these that the person has journalistic training.
    (2) If the hum were in the range of 440 Hz, we could likely expect excellent descriptions (e.g., sounds like a trumpet at 500 Hz). It’s not of course. It’s low in pitch and loudness. Very difficult to pitch match, even for experienced matchers who likely also try very hard. Don’t suppose it’s easy.
    (3) In working with synthesized sound for 45 years, and writing about it, one of the most difficult things is describing in words what something SOUNDS like. We are VERY LUCKY to say that it sounds like a truck. Mostly we have to use analogy, and the same (relatively few) comparisons keep occurring. This is especially valuable when it is spontaneously offered (like “I went out expecting to see a utility truck, yellow light flashing, two blocks up”).
    Don’t sell this short – it’s all you get!

  11. Henrik says:


    You make strong points here, and you are an audio expert so you know what you are talking about. I only hope that among the 16,000 reporters to the Hum Map and the millions of Hum hearers around the globe, there would be a few who might make other associations than the idling engine. That could be helpful for those neurologists, who will ultimately resolve the mechanisms behind the otoacoustic Hum.

    What we mortals can do in the meantime is to try to find the reasons why only very few people are affected out of the total population. The Hum hearers would especially like to know whether it could be reversible by removing the factors which has caused the Hum. So let’s focus on finding the possible triggers and situations when it started, as I suggested in my initial posting.

    And all those who say that their hum starts at certain times of the day, or is not there certain weekdays or times of the year, etc., should start chasing environmental noises, and think over what could have caused their hyperacusis, if others in the same time and place do not hear it. Please refer to my original posting.

    My “favorite villains” at this point are wind power plants for the acoustic hum, and medications for the otoacoustic hum. But I reserve the right to adjust my opinions in the light of new findings.

  12. Henrik – glad for your scientific skills here. Let’s use some.

    (1) Yes, some are environmental noise. If you have two people together (randomly – not a collaboration of separately selected Hum hearers), the chance that both hear the (otoacoustic) Hum is remote (like 1 in 0.02^2 = 1 in 0.0004). Most likely real sound.

    (2) There seems to be no physical acoustic version of the real Hum. And possible RF origins are very unlikely due to lack of likely transmission patterns, unsuccessful blockings, and unspecified mechanisms.

    (3) The interruption by head-shake/grunt of the Hum means it is internal.

    (4) The fact that the Hum is sometimes shut down by air travel for days strongly suggests that pressure resets in the middle ear “shake up” a generation mechanism which may be there.

    (5) No physical condition or medication is obviously seen to be common, while hearing abnormalities are relatively common, although varied. Who hears perfectly? Not many.

    (6) Why ask why the Hum is rare? Lots of afflictions are AS rare or even much rarer.

    (7) Clearly not all neurologists are equally skilled or curious. Probably most never heard of the Hum, or just dismiss it as a nuisance. Resources for investigation seem unlikely.

    (8) There are some very good report here (as I said – journalistic) but keep in mind that quite a few here are not receptive to a prosaic (non-UFO) explanation.

    (9) Let’s not put too much stock in reports of the Hum coming and going. Lots of afflictions (say, arthritis) come and go for various, often unknown reasons. If very regular in pattern, it’s likely a real sound, infrastructural, military, or industrial.

    Please feel free to add-to/subtract-from my list here. -Bernie

    • Henrik says:

      I would say we have a 75% agreement on the points you list in your Hum Cathechismus above. I have some comments on items 5, 6 and 7.

      (5): I think we should focus precisely on finding correlations with medications and other medical conditions and environmental factors among the Hum hearers. I do not see any necessary connection between otoacoustic experiences and whether the person has “normal” hearing capabilities, since the eardrum is not involved in otoacoustic phenomena.

      (6): I find it absolutely essential to find out in what respect Hum hearers are different from the general population, just like science struggles to find genetic, lifestyle and environmental differentiators to identify the root causes of all non-communicable diseases, like Alzheimer’s, Autism and cancer. The Hum is in my opinion “a non-communicable condition”, if not exactly a disease.

      (7): I think only a neurologist can continue this research from here. It may be difficult to raise funding, but maybe we can dig up some Hum-hearer who happens to be a neurologist :-). What is the probability of that, Dr. Watson?

      I would like to think that our sparring on these questions has helped the World Hum Project a little bit on the way towards a result, by practically eliminating a long list of old suspects and speculations:

      – Environmental and seismic noise (acoustic) [These have generated some of the Hum Map observations, but do not constitute the World Hum phenomenon]
      – Microwave, cellphone towers, radio stations and submarines; RF of all frequencies [Possible sensitizers but not real-time triggers]
      – Power-line and household appliances’ EMF
      – UFOs and conspiracy theories (already earlier dismissed by Dr. MacPherson)

      If there are people with medical training among the Hum hearers, please step up to the plate!

  13. Lisa Allen says:

    Henrik – Here’s an odd thing: after I fly I don’t hear the hum. This has happened twice now. What does flying do to the ears that blocks out the sound? Last year when I returned from a trip to Alaska I didn’t hear the hum for a few days, but then it became audible again. And two days ago I flew back from New York and I still can’t hear the hum. Before I left it was very loud. I expect it will return soon. I hear everything else normally and do not feel that my ears are blocked. I did have to take a Sudafed and use Afrin spray to avoid ear pain that normally occurs when I fly.
    By the way, maybe I’m in the minority but I would not describe the hum as sounding like an idling truck engine.
    Thanks for trying to help us out – it’s greatly appreciated!

    • Henrik says:

      Lisa: Your observation, which is reported by quite a few people, may be a very important clue in finding the real mechanisms for the otoacoustic Hum. Unfortunately further research into otoacoustics fall outside the knowledge of an electrical engineer like me. But I would be curious to know how you would describe the Hum you hear?

    • SGVH says:

      Are Sudafed & Afrin anti-histamines?

      Professor Belpomme (France) studies have shown that EHS people have “neuro-inflammation” caused by “Electromagnetic Fields.” The neuro-inflammation, among ither things, causes Histamine levels to increase by 40%.


      Maybe high histamine levels, from whatever cause–not just from EMFs– is what causes “hum-hearing”?

      • Henrik says:

        Sudafed and Afrin are both decongestants. Sudafed contains some nasty ingredients, which belong to controlled substances in certain countries. Beyond this Wikipedia-info I don’t want to dabble in a subject I am not familiar with. Maybe someone else can help?

  14. SGVH says:

    This is a total guess: Maybe the Sudafed/Afrin DEcreased your Histamine levels causing hum to disappear for a few days, until the Sudafed/Afrin wears off / exits body. Then the Histamine levels rise again > & hum returns. (???)

    • SGVH
      Does everyone who flies use Sudafed/Afrin, and only when they fly? Is it not likely that people who use one or both would have does so on the ground, with the same effects, and noticed if the Hum appeared/disappeared?

      • SGVH says:

        “Does everyone [who hears hum] who flies use Sudafed/Afrin, and only when they fly?”

        Well, Bernie, unless Glen adds that question to his Hum Map questionaire, I guess we’ll never know for sure. 😉 It would be hard to go back & ask 16,000+ people.

        “Is it not likely that people who use one or both would have does so on the ground, with the same effects, and noticed if the Hum appeared/disappeared?”

        Unless they are analytical thinkers like yourself, I suppose it’s possible some people may not connect the two (if it is even a remote possibility that high histamine causes some people’s ability to hear the hum, since as of now we are just guessing/throwing out ideas based on Lisa’s anti-histamine/decongestant OTC’s & Belpomme’s increased-histamine levels research).

        It’s fun to analyze, though, isn’t it? 🙂

  15. Lisa Allen says:

    Henrik – When I first started to hear the hum I thought it was a bass from a neighbor or a car parked down the street. But the hum has two sounds for me: one is that bass like sound, which I hear during the day, and the other, which is louder and more annoying, is a steady drone, like a low frequency feedback from a sound system or microphone and usually occurs at night. It can get so loud that I have no doubt that it is not internally generated and I can’t believe others can’t hear it.
    For what it’s worth I have two autoimmune diseases and have been taking medication for a long time. I have wondered if that has caused my ears to become more sensitive in some way. Autoimmune diseases cause inflammation and many are systemic; I wonder if something in the ears are inflamed and that is increasing my ability to hear low frequency.
    SGVH – Sudafed in a combination antihistamine and decongestant, and Afrin is an antihistamine. I don’t believe the hum has gone away when I’ve taken a Benadryl, but it’s definitely worth trying again – even a decrease in the sound when it’s very loud would be welcomed.

    • Thanks Lisa –
      You said: “…..a steady drone, like a low frequency feedback from a sound system or microphone…”
      Do you have any idea what the pitch is? Can you match it to a tone from an online tone generator such as?
      Beyond general information, the description “low frequency” is generally not one that would be used to describe “feedback from a sound system”. Such pitch is determined, usually, by a room resonance and tends to be medium to high in pitch.
      – Bernie

    • SGVH says:

      Hi Lisa, I empathize with your autoimmune conditions. I can relate to similar immune dysfunctions.

      Thanks for the Sudafed/Afrin details. It was just a guess on my part. I don’t take any meds (not a fan of Big Pharma). I did try Benadryl once back when it was recommended as an OTC sleeping aid but, ugh! Talk about “cotton head hangover” & dry me out like a bone dry desert. I couldn’t handle it.

      “I wonder if something in the ears are inflamed and that is increasing my ability to hear low frequency.”

      Good question.
      More guessing here:

      1. Inflamed ears hear LF.
      2. Uninflamed ears do not.

      A quick google showed that Sudafed has “pseudoephedrine” which can unblock “eustachian ostia” > (ostia/ostium > the mouth-shaped openings to the tubes).

      So (still supposing), inflamed hum-hearing “eustachian ostia” get unblocked/uninflamed temporarily by “pseudoephedrine” & hum cannot be heard.

      Upon re-inflammation/re-blocking, hum returns.

      A true connection? I have no idea; would have to ask Henrik & Bernie, the scientists. 🙂

  16. Charlie says:

    Hi Henrik
    When I hear the Hum it is often seems to be predominantly about 120 Hz or so. (Earplugs etc have no effect upon it.) Other people here have reported ‘hearing’ the Hum as being around the 50 – 60 Hz mark
    I was wondering how it could be possible that infrasound (<20Hz) could be be responsible for people 'hearing' a much higher frequency sound (ie. 50 – 120Hz).
    Can infrasound actually do this? As you know, infrasound is sometimes mentioned as a possible source of the Hum on this site. So this is not the first time I have wondered about this question. But unfortunately my Google searches haven't produced much of any use. All I have found so far is that infrasound can cause certain psychological effects in humans, such as feelings of awe. (Wikipedia has small section on this in their infrasound article.) But I haven't found anything yet about infrasound creating the perception of higher frequency sounds.
    If you could point me in the direction of any info on this aspect of infrasound I would truly appreciate it.

    • Henrik says:

      Hi, Charlie,
      The “Missing Fundamental” is a very real phenomenon, and is for example utilized in basic telephony. But the phenomenon is created in the brain and is not a technology gimmick. Wikipedia has a good write-up on this subject. And yes, there are also write-ups in relation to wind power plants, claiming that some of the annoyance comes from this phenomenon, when the brain converts infrasound to “audible” noise. And then the wind power company goes out with an A-weighted sound pressure meter and “proves that the noise is about the same as the noise from the wind”. This is a total and deliberate scam, since the A-curve and the eardrums have nothing to do with how we perceive infrasound, as I pointed out in my initial posting. I am afraid that my attitude towards the wind power industry somehow shines through here, but “Here I stand. I cannot do otherwise. God help me, Amen!” [For those who forgot their history: Martin Luther, Worms, Germany, 1521].

  17. SGVH says:

    Have you guys ever seen this quote by Nikola Tesla’s friend & biographer, John O’Neill, re Tesla’s severe sensitivities in his later years? Talk about torture…

    In the case of Tesla, it was reported in his biography written by his friend John O’Neill that he suffered greatly in his later years:

    “To doctors he appeared at death’s door. The strange manifestations he exhibited attracted the attention of a renowned physician, who declared that medical science could do nothing to aid him. One of the symptoms of the illness was an acute sensitivity of all the sense-organs. His senses had always been extremely keen, but this sensitivity was now so tremendously exaggerated that the effects were a form of torture. The ticking of a watch three rooms away sounded like the beat of hammers on an anvil. The vibration of ordinary city traffic, when transmitted through a chair or bench, pounded through his body. It was necessary to place the legs of his bed on rubber pads to eliminate the vibrations. Ordinary speech sounded like thunderous pandemonium. The slightest touch had the mental effect of a tremendous blow. A beam of sunlight shining on him produced the effect of an internal explosion. In the dark he could sense an object at a distance of a dozen feet by a peculiar creepy sensation in his forehead. His whole body was constantly wracked by twitches and tremors. His pulse, he said, would vary from a few feeble throbs per minute to more than a hundred and fifty. Throughout this mysterious illness he was fighting with a powerful desire to recover his normal condition.”

    Wow!! What a horror his later life must have been. So sad for him. Amazingly, Tesla lived to age 86, died in 1943; lived in NYC 60 years, one of the first cities to be electrified, in addition to his over-exposing himself to EMR in his experiments, from Alternating Current/ELF to “wireless” RF.

    • Henrik says:

      SGVH: That was an interesting input, which supports the idea of sensitizing, of more than the hearing sense, by RF exposure. But then again, we must be careful with scientific “outliers” like Nicola Tesla. His exposure to electromagnetic radiation of all wavelengths, from 60Hz to ultraviolet light and possibly even X-rays from spark arcs, was so extreme, that he may have been affected by other physiological mechanisms than just neurological ones. There is an enormous difference between the kilowatts (10exp3) he experimented with and the nanowatts (10exp-9) we receive from a cellphone tower, so don’t try to use this for scaremongering against cellphone towers!
      From a scientific point of view, the first question to ask would be: Did his laboratory assistants have any similar symptoms? If the answer is no, his illness may not even have anything to do with RF at all. It is easy to get carried away, in science as in crime investigations…

  18. Lisa Allen says:

    Bernie, I agree with what you said – “Beyond general information, the description “low frequency” is generally not one that would be used to describe “feedback from a sound system”. What I hear is similar in some ways to that sound but isn’t identical to it. But it is a closer description then anything else I can think of. I am curious to try your tone generator but will wait until the hum is back in full force, and will then try to match it.

    SGVH – I feel the same way about benadryl – way too drying and makes me very groggy! I only use the sudafed/Afrin when I fly as that is what the ENT doctor recommended for ear pain and thankfully, it works. So many people who hear the hum do not appear to have any medical problems or take medication so inflammation doesn’t seem like it would be the cause of sensitized hearing for everyone, but maybe it is for some of us. There must be other things that cause hyperacusis (sp?) too. Ironically, I wore ear plugs for years and years as I am a light sleeper. But now that I hear the hum, ear plugs only make it louder and I can’t use them anymore. I wondered if the ear plugs did something to my ears, too.

    I didn’t know the horrible suffering that Tesla went through. What on earth would cause those symptoms?? That’s such a sad story.

  19. Ann Ferguson says:

    I presume Henrik you are aware that some people who have Asperger’s Syndrome are sensative to sound. I know this because 2 of my grandchildren have this problem and can find simple things, like people laughing, painful. Just thought this is something which should be considered in some cases.

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