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We should take a second look at this

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Follow World Hum Map and Database Project on WordPress.com

A few years ago I posted on this topic, and a few minutes ago I rediscovered why. As evidence piles up against EM-based theories (VLF radio, microwave, etc), I’m leaning toward the theory that the Worldwide Hum is an internally generated perception of sound and in some cases, vibration. Note that there may be external triggers or pre-requisites, such as ototoxic medications, environmental exposure, infrasound, and so on.

So focusing back on medical diagnostics, take a look at this startling experimental result: http://digitalcommons.northgeorgia.edu/cgi/viewcontent.cgi?article=1049&context=papersandpubs.

Allow me to offer an executive summary: When you strike a deep bass note on the piano, for example, the piano string vibrates strongly at that fundamental dominant frequency, which is what you hear. But, the string also vibrates at other frequencies, called overtones. (It is the mixture of these different harmonics and overtones that make each musical instrument and voice unique.) Musicians will know these overtones as the third, the fifth, the seventh, and so on. The fascinating thing is, if those harmonics and overtones – without the fundamental – are played to you, your ear and brain will create the fundamental note for you, and you would swear that you can hear the fundamental bass note being played!  I don’t use exclamation points very often, but this is quite remarkable. This effect is called the missing fundamental. The undergraduate researchers in the above paper conducted a brilliant experiment in which they played tones that created an infrasonic missing fundamental. That is, the brain created a note that was below the range of hearing. They measured the brain response using EEG recordings which clearly showed the missing fundamental rising at 18Hz.

So then I had an idea. We should do something very similar. The important lesson from the above study is that there are external experimental techniques that can validate real or perceived sounds. This could separate Hum hearing from schizophrenia, otoacoustic emissions, tinnitus, or other phenomena, just for starters.

We don’t need to create the missing fundamental. If we are perceiving, say, a 47 Hz tone, then the EEG might show that. It also might show whether that perceived Hum disappears in the presence of masking noise, or whether it is persistent. If a 47 Hz signal cannot be read on the EEG, then this will point neurologists toward different hypotheses. It seems to me that no matter what the result, we can use the data generated.

Please let me know if you have connections in the medical world who might be interested in making this happen.


  1. Good job by these students (A+). Good experiment and very clear report (although I don’t see what the summation equation is doing there). Not a surprising result. And note that there is nothing special about their 18.5 Hz. What is relevant is that their choice is significantly BELOW audible pitches (better considered to be 30Hz-40Hz rather than 20Hz) yet ABOVE the rates where we perceive a repetition rate (rather than a pitch). This latter rate is about 7Hz-8Hz and below. This, by coincidence, I have recently discussed:


    (see pages 2-3). This describes a low-frequency experiment you can do yourself if you can round up the “equipment” of a plastic ruler, the edge of a table, and retain the proclivity (since 3rd grade) of making noise that annoys other people!

    The case of what the authors call Broken Missing Fundamental (using 37Hz and 92.5Hz) is likely the repetition rate of a “beating” envelope (the red arrows they rightly noticed in their Fig. 1). Likely this is more a part of the brain’s pattern recognition ability than it is pitch perception. More on beating:


    Refreshing find.


  2. Henrik says:

    Very interesting research indeed! The basic phenomenon of the Missing Fundamental is well known, and Wikipedia has a good write-up on the subject.

    To my understanding, the really new thing in this research is the hypothesis of “synchrony induced through stochastic resonance” in neural networks (page 9). This opens a new dimension and displays obvious similarities with how electronic oscillators and resonant circuits work.

    I made one observation in the lower left blue diagram in Fig.2: There is a clear spectral peak with increased coherence in the range 0.7-1.5 Hz, which, however, had not been expanded by the researchers. This could possibly have something to do with the pulsating “diesel” sound so many Hum hearers report. Of course, this is also the frequency range of normal heartbeats, so there may also be no connection to the pulsating sound – unless the pulsation effect comes from the blood pressure variations from the heart beats…

    Maybe Dr. MacPherson could contact the research team and ask them if they could go back to the recordings and expand the area 0.7-1.5 Hz in the same manner as they did for the 18 Hz region?

    Beyond that, I have to throw in the towel on neural networks. 🙂

    • Hi Henrik – two things

      (1) I too noted the passing reference to stochastic resonance (SR). Not sure why it is there, although they did add pink noise to the pure tones. SR is generally associated with detection at near threshold levels, which the Hum may be, but NOT the experiment in the paper. (Incidentally, SR is a poorly chosen term as it is unrelated to the
      usual electrical or mechanical resonances.) SR is closely related to “dither” in digital audio (resolving below the LSB). SR was “invented” by nature (like crayfish in a noisy stream!). Here it is related to digital audio issues:
      (see page 15).

      (2) You are quite right to mention the “surging” of the idling diesel engine analogy. This roughly 1 Hz shallow amplitude variation significantly enhances the resemblance to the engine. I have advocated the full “interruption” of the Hum by grunt or headshake, as being diagnostic, whereby the hum stops for a half second and then ramps right back up. If one tries to hold it down by continuous shaking, you can only do this for perhaps 5 seconds at most, during which you will hear several inadvertent partial comebacks. You can’t shake consistently. The corollary to this is that you can’t hold perfectly still, and there are almost certainly partial dropouts. If you hold as still as possible, the surges are noticeably reduced.

      – Bernie hutchins@ece,cornell.edu

  3. Janet Menage says:

    Another interesting find is ‘Musical Ear Syndrome’: http://hearinglosshelp.com/blog/musical-ear-syndrome-the-phantom-voices-ethereal-music-other-spooky-sounds-many-hard-of-hearing-people-secretly-experience/. Noteworthy, is the person who thought there was a truck idling outside the house. Also, that some people feel vibration associated with the non-psychiatric auditory hallucinations, and that the phenomenon tends to occur in quiet environments.
    Do we have age/gender data on hum sufferers, I wonder?
    It might be useful to contact the author? Something else to add to your to-do list, Glen! 🙂

  4. Kurt says:

    Fantastic idea


    I privately emailed this idea to two readers (who had contacted me directly), who in return suggested I post it here. It is a very easy online experiment relating beating and the missing-fundamental phenomena.

    The human ear/brain is not a rule-based computer, particularly with regard to the perception of pitch. It does not pay to suppose that there is a procedure that an engineer can describe to say what results will come out. This is particularly true for a comparison of the phenomenon of “beating”’ and that of a “missing fundamental”.

    Using a popular online tone generator:

    load TWO copies. (Run together, the two tones add). Set the frequency to 185 Hz (all sine waves here) and play, listening for a clean tone of pitch 185 Hz. Now set the 2nd generator to 186 Hz and add. The tone changes to 185.5 Hz (which you won’t notice) but you WILL recognize a full amplitude modulation at 1 Hz.

    By trig identity,

    sin(A) + sin(B) = 2 sin((A+B)/2)cos⁡((A-B)/2)

    we see the average frequency and HALF the difference frequency. This would be 1/2 Hz (once every two seconds) and yet we hear AM at 1 Hz. Why? Because there are TWO amplitude peaks for each cycle of the difference frequency (one positive, and one negative). This simple fact is often confusing.

    Next go ahead and set the second generator to 187 Hz (a 2 Hz beating) and so on up to 193 Hz. At this point, 193 Hz, you will probably just begin to notice the pitch shift to 189 Hz and a deep beating rate of 8 Hz which may become a bit annoying. (You can barely follow the AM.) Continuing up to 203.5 Hz, the beat rate is 18.5 Hz and a very “rough” overall perception, but a coherent test sound. You can continue. At 277.5 for the second tone, you will hear a 92.5 Hz pitch and no real notion of beating. Nice tone.

    Notice that we have seamlessly transitioned from beats to missing fundamental (MF)! The math must have been the same. Indeed, the beating at 1 Hz was the 185th and 186th “harmonics” of a missing 1 Hz fundamental! A horrendously large gap between 1st and the 185th and 186th pair. Beating at 18.5 Hz, produced by the 10th harmonic (185 Hz) and the 11th harmonic (203.5 Hz) is still a stretch of the MF idea (and an infrasonic pitch of 18.5 Hz). However, the case of 185 Hz as 2nd harmonic and 277.5 Hz as third harmonic (92.5 Hz fundamental) is classic audible-range MF- a lower pitch. And the harmonics support a stronger pitch – compare to just the 92.5 Hz sine wave.

    Same math. Different regimes at the ear/brain. Do this exercise and you will understand more about the issues than most engineers.

    Bernie hutchins@ece.cornell.edu

  6. Jessi Jean says:

    Not relevant but the piano thing… I can only hear the higher and lower key itself hitting the wood. *tap tap* ….with my hearing aides. I am too Deaf to pick up much frequencies with them. Yet the Hum and harmony is incredibly loud inside my head….. I’m stumped man!!! It may seem louder to me because hearing people have sounds to push it to the background. I got nothing. Have booked an appointment to see if my hearing test can test the really low frequencies 🙂

  7. Lisa Allen says:

    I am just curious to know if when the experiment was conducted with the Deming box that is supposed to block out VFL radio waves, if there was any instrumentation placed inside the box measuring VFL to corroborate the findings?

    • Yes, and no, respectively. I did indeed enter the Deming Box, and it had no effect whatsoever on my perception of the Hum. I wrote about that elsewhere on this blog. I am waiting – for too long now – to redo the experiment with a VLF metered device. I need to make some adjustments to that device, which was built by George G., a contributor to this blog. When that is finished, stay tuned for those results.

    • Hi Lisa –

      The high significance of Glen’s (negative) Deming Box (DB) observations should be understood. He heard no noticeable blocking of the hum.

      To some extent, a DB should resemble a low-pass filter – not an instantaneous cutoff. We know (Glen’s result) that his frequency of 56 Hz (if it is the cause of the Hum) would have to get through. At the same time, normal strength RF signals as high as 530 kHz, and higher, are easily blocked even by much more open metal structures, such as highway overbridges or my equipment cabinet (http://electronotes.netfirms.com/ENWN47.pdf). The superior DB would almost certainly show the same rejection at 530 kHz and a noticeable rejection well below that (perhaps to 50 kHz) relative to my leaky metal cabinet. There is, however, no problem with a low-pass filter passing 56 Hz virtually unattenuated while virtually rejecting 530 kHz. But, this is BEFORE we worry about modulation.

      If an RF signal is modulated, the 56 Hz would have to ride in on a carrier of much higher frequency (perhaps 5600 Hz – a factor of 100 or so as used in broadcast AM). So the frequency window is getting narrow. And once we bring in the possibility of modulation, we would need to consider perhaps a half dozen demodulation schemes (back to 56 Hz) either for test instrumentation, or naturally for the person inside the DB.

      Not at all an easy job.


      • Lisa Allen says:

        Hi Bernie,

        Thanks for explaining how this works – I can see it is pretty complicated. My only thought was “trust but verify” (the deming box’s ability to block VLF as well as it it thought to)” but I guess it’s not that simple.


      • Lisa –

        True: “trust but verify” is an attractive notion, but what is the expense (the OVERALL impracticality) of further testing, especially in attempting to prove a nebulous negative! No RF? No problem – it’s a Higgs Boson that quantum-mechanically tunneled in. Prove that ain’t so. Glen’s fine experiment (along with other evidence) suggests we wait for a well-considered positive result.


  8. Carl says:

    To state the hum is a internally generated sound would prove that there is something causing people from 11 years to say 80 years of age to suddenly recieve damage physiologically by sone uknown agent.
    The sonic attack caused long term damage to the diplomats

  9. Dorothy says:

    The US Embassy workers in Havana, Cuba, experienced symptoms that included “dizziness, tinnitus, balance … problems, headache, fatigue, cognitive issues and difficulty sleeping”, according to this Sept 29, 2017 New York Time article:

    The above symptoms are amazingly similar to my experience of the Hum in my home in 2011, although I could never be sure whether the low pulsing drone I experienced was vibration or sound. (And by the way, I never thought I was being attacked or targeted…, still don’t.)

    Another article on the US Embassy ‘attacks’ says that this couldn’t be from an electromagnetic device, it had to be from a sonic device because the ‘attacks’ were emitting a sound that has been recorded at particular locations.

    Isn’t this the proof that such symptoms are caused by external factors?

    But in my humble opinion, recorded sound does not necessarily eliminate an electromagnetic source, since some electromagnetic fields do at times produce audible sounds. For example, the hum one hears below high voltage power lines.

    • Henrik says:

      The only way a magnetic field can cause audible sound is by generating mechanical vibrations in a metallic object. The humming sound we hear under a power line is usually a corona discharge with a repetition frequency of 120 Hz (Europe 100Hz) and is not caused by any magnetic field.

      To me the recording sounds like an electronic device, which has malfunctioned (cheap energy-saver lamp?), or an electronic insect repellant device or a so-called dog silencer (anti-barking) device. Since we know nothing about the origin of this recording beyond hearsay, I would not give it any evidence value. If the recording was not made with an electret or condenser microphone, we do not even know whether we listen to a recording of a magnetic field or actual acoustics. Personally I strongly doubt that that recording has anything to do with the symptoms reported.

    • Dorothy –

      You said in part “. . . .similar to my experience of the Hum in my home in 2011, . . . .”

      So we wonder, for your case, if you still hear the Hum (since 2011), and if not, what changed? Did it just stop? Did you move? Or what – if you care to tell us?


  10. George G. says:

    I came across a devilish device one day inside a remote microwave radio relay station.

    The device emitted an ear piercing screeching composed of multiple high pitch odd harmonics, clashing together at extreme levels.

    Its purpose was to repel rodents and insects, and hopefully stop them from damaging equipment.

    Unable to concentrate and feeling discomfort in our ears and stomachs, we switched the device off.

    If any similarity exists between my experience and what has been experienced in Cuba, I would suggest there is a simple explanation behind the total nonsense currently reported.

    Today’s media seem to carry a surplus of lazy journalists—-it’s easier to produce conspiracies rather than carry out fact finding journalism, much less effort involved.

    Attempting to link the Hum, as we know it, to the Cuba incident, can only prove fruitless.

    • Henrik says:

      George, I think you may be perfectly correct. I have lived for decades in tropical countries, where expats typically resort to these cockroach- and rodent repellants, in addition to professional use in microwave stations. They are supposed to work outside the human hearing range, but cheap components cause nonlinearities, and small objects can resonate at sub-harmonics if the level is high. Two simple questions to the affected families in Havana would be (a) did they use any electronic repellant device, and (b) did they have dogs? These things drive dogs crazy. There are special outdoor high-powered dog-silencers (anti-barking devices) as a last resort against neighbors’ dogs. Maybe desperate neighbors in Havana used these against diplomat-family dogs, and got the arrogant owners to leave as a bonus? .

      But let’s go back to the drawing board. This side-track has nothing to do with The Hum.

    • Janet Menage says:

      The screeching was clearly within the audible range. But what if the noise was above the human ability to hear it? – potentially, the physical ill-effects could still be the same. What mechanism(s) do you think caused the unpleasant symptoms? Is it likely that other types of microwave relay stations (not necessarily radio) use this type of rodent/insect-repelling apparatus at frequencies which we cannot hear?

    • Janet Menage says:

      I came across an ultrasonic teenager deterrent! – http://www.abcfireandsecurity.co.uk/Teenager%20Dispersal.htm?gclid=CjwKCAjw4KvPBRBeEiwAIqCB-Ra1knFk1CxAt9KpGb5Lvcu2lXr2S6jFABuEJVzUWqfYpSnk0oAmoRoCjYcQAvD_BwE
      What is interesting is that it says adults cannot hear the noise but teenagers feel ill-effects and move away from the vicinity of the device.

  11. Henrik says:

    This discussion thread is now veering into conspiracy theories and “targeted individuals” and microwaves, which theories have all been thrown out as possible causes of a global phenomenon. While it is fun to speculate about these things, it does not bring the project forward :-).

    Let’s recall that we are looking for a cause of a low-frequent Hum, which millions of people “hear” or feel, all over the world, even where there is no electric power within miles. In my not-so-humble opinion we should focus our brainpower on the two main possibilities that have been identified, i.e. actual infrasonic or low-frequency pressure waves or “sounds” carried through the air or the ground, and internally generated otoacoustic phenomena. Most likely some 90% of all Hum observations can be explained by either of these two causes, but we need to also understand the physiological/biological action mechanisms before we can arrive at a possible remedy.

  12. Dorothy says:

    Thanks Bernie for your question, it is helpful for all of us to compare notes. From January to June 2011 I terribly suffered from this low pulsating drone at night, which caused severe insomnia, headaches, chest pain, irregular heartbeat, tingling, etc. And no I didn’t move. I was affected within a 30 km radius of my home town, but when I travelled across the continent for a couple of weeks I was symptom-free.

    Long story short, when I heard that long-term exposure to microwave radiation may increase one’s sensitivity to low frequencies, I got rid of the cordless phone that had for years been sitting beside my bed. And something apparently changed with the powerful wifi system of the high school next door.

    I still perceive the Hum now and then, too faintly to be a nuisance. It has been my observation that the occasional times when I faintly perceive the Hum these past few years (always when I’m lying in bed in the early morning hours) have mostly been connected to earthquakes and solar flares. For example, when we had this 6.1 earthquake here in the Yukon in May 2017, I had a faint hum a couple of days before and after the earthquake. Piezoelectric phenomena occur prior to earthquakes and can travel far and affect the earth’s EM field. See: http://www.eqsigns.net/piezoelectric.html
    I note that my severe 2011 hum episode corresponded to the catastrophic March 2011 Japanese 9.1 earthquake…

    In my opinion, the hum is probably caused by a combination of factors, such as exposure to shifting electromagnetic fields (earth’s and/or man-made), which may cause infrasound, and individual sensitivity. There are also diurnal shifts to the earth’s electromagnetic field (i.e. compressed by solar wind during the day, diffuse at night) which could explain why the hum is often worse at night. Maybe intersecting EM fields are resonating at certain locations, causing iron ions within our body cells to vibrate?

    I would be most interested to hear others’ thoughts and observations about this.

    • Janet Menage says:

      Bioinitiative.org states:- There are studies on the effects of cell phone radiation and the auditory system. Most research (Kwon 2009, 2010a, b; Parazzini et al., 2009; Stefanics et al., 2007, 2008) reported no effects, which seems to agree with the pre-2007 studies in this area.
      However, there are two reports by Kaprana et al. (2011) and Khullar et al (2013) showing effects on auditory brainstem response, two papers by Panda et al (2010, 2011) that concluded: “Long-term and intensive GSM and CDMA mobile phone use may cause damage to cochlea as well as the auditory cortex.”, and a paper (Mandala et al., 2013) reporting effect on auditory-evoked cohlear nerve response. Maskey et al. (2013) reported chemical changes in the superiou olivary complex, a neural component of the auditory system, in mice after chronic exposure to RFR. Velayutham et al. (2014) reported hearing loss in cell phone users and Sudan et al. (2013) observed weak associations between cell phone use and hearing loss in children at age 7.

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