Here is Henrik’s latest Logic Flow Map for those seriously interested in World Hum research.
I have the pleasure of presenting this work by Henrik, one of our forum contributors with serious scientific credentials. (Henrik, along with Bernie Hutchins, played a major role in developing the new version of our Hum Map Survey). It is a logic flow diagram that sorts out the logic and decision making regarding the source of the Worldwide Hum. It will prove valuable for scientists new to the phenomenon, those who are scientifically literate, and those who have already invested time and energy into this issue.
This is a great addition to the project, Glen. On my review of the chart, it would appear that organic internal causes (except for stress) have been ruled out. Am I reading this correctly? If that is the case, may I ask why? Or am I wrong? Thanks.
Actually, the way I read the flow chart tells me organic internal causes are very much still in the race.
My statement above may be considered incorrect because I bypassed the Possible Causes column.
By doing this, I am inadvertently declaring the Hum I doesn’t require a triggering mechanism. (Freudian slip I suspect)
If we read the chart starting from the left and finishing at the right, then Harvey is correct.
I think the chart was ONLY meant to include the popular proposed EXTERNAL causes, and shows what is then needed in each case in order to observe hearing only by a FEW individuals (rather than by all individuals co-located in place/time – see bold text at bottom of the rectangular box). Add the truncated “body/brain” to the caption at the bottom, and internal causes are the residual possibilities – live and well.
The Logical Map (Rev 7) seems to have a truncated caption. A previous version (Rev 6) had the words “body/brain” following “individual’s”.
Thanks for clarifying this truncation. To me, as we’ve discussed before, “inside the individual’s body/brain” is really the most viable of all the possible causes. I would like to see a logic flow that concentrates on the possible causes emanating inside the human body. I’ve attempted to get my neurologist interested, but no luck! Same with every other professional medical practitioner I’ve discussed the phenomenon with. What ever happened to scientific curiosity?
Doesn’t pay the bills, unfortunately.
This is really up to us to solve—and solve it we will.
I’ve updated the picture so that it should be entirely visible now.
Thank you Henrik – that’s a very impressive chart. Thank you Glen and Bernie, too.
I have contacted Dr. MacPherson to fix the truncated text at the bottom. It should read “… the individual’s head/brain.” Since I am many time zones away, our communication is not real-time.
As I have mentioned before, I am a non-hearer, so I have no personal bias concerning the ultimate causes/solutions. This is only a thinking template with the purpose of reducing the amount of whimsical postings and ramblings that occasionally fill up our blog.
The focus of our analysis must always be on the dotted-line box, the “Individual Sensitization”. That is the key characteristic of The Hum and the only window to finding an answer. Indeed it looks like the project would need more medical expertise than engineers like me.
Thank you, Henrik. Very useful.
1. How can I make recordings of Hum, so that they can be analysed? Most of the recorders that I have record mush at the low frequencies that I attribute to thermal noise in the front end.
2. With Hum being “all around” when I go outside, how can I determine the direction from which the noise is coming, thus enabling me to locate the local source?
3. RFI at low frequencies can arise from overhead telephone lines that carry ADSL signals to routers. Could these be a source of audible hum as well?
If these points could be understood, they would be way of practically implementing your logic (possibly).
1. The only situation where it would be interesting to record environmental low-frequency noise (“hum”) is if you are in a situation, where you consistently and repeatedly hear a low-frequency hum, but nobody else can hear it. For that you need rather advanced recording equipment, which must use an electret or condenser microphone to eliminate electromagnetic fields and must have very low thermal noise. Hobby recorders are useless for this purpose.
2. It is very difficult to determine the direction of low-frequency sounds. You have to move around.
3. No. ADSL lines cannot produce audible sounds.
Although some people are suffering from environmental noises due to hyperacusis, this is not the generalized “Hum” we try to identify. The World Hum follows the sufferer over great distances.
Thank you very much for your detailed and useful reply.
1. We are in the situation where my wife and I, together with several people close by, are aware of a hum that is constant and fairly consistent in amplitude. I have measured around 40dBc as normal. The issue is that the person from the local council could not hear it on the day she was here – and therefore it doesn’t exist, which is frustrating to say the least. Hence the reason for wanting to record it. She also has to know the source before she can do anything about it.
2. I agree with you that even the recorders that claim to be low noise have too much thermal noise at the front end, which masks the noise. Any ideas of equipment type that I could hire or buy would be useful.
3. Thanks for the information concerning VSDL/ADSL twisted pairs. It can cause RFI problems for radio amateurs, of which I am one. I shall not pursue that line any further.
Our noise is almost certainly man-made. The only issue is tracing it and then, just perhaps, something can be done about it.
Keith – Thanks for the comments.
You said “. . . my wife and I, together with several people close by, are aware of a hum. . .”
(1) Anytime more than one person claims to hear something (the traditional Hum in this case) that is supposedly heard by only 2% of the population, the indication is that what is involved is NOT the traditional Hum.
(2) If your meter says 40dB (c-weighting), which is a very low level, how did you determine that this was the hum you hear and not just normal random background? [Or is your meter tuned (a spectrum analyzer)?] If the level is this low, it is hardly surprising that a local official popping in off the street (as opposed to a technician with time, care, and equipment) did not hear anything?
(3) What pitch does your hum match to?
Keith, I agree with you that it is man made. When the construction inspector and the power reps were out here I had the same problem, they couldn’t hear/feel it. My St farm home insurance agent told me to put a pan of water on the floor and take video of it , if the water moves. He believed me about the vibrations/pulsing, but cannot do anything to support me because there is “no proof.” That is the most frustrating obstacle in dealing with this thing. Also, it’s hard to get anyone out here at night when it is the most active. I had the DOT out here at first because I was convinced that it was construction/pile driving but it is ruled out. I noticed that there are several dots on the data base here in the Orlando area all around me.
Your agent is spot on. It is well worth the effort to follow his advice.
A favour please; should you decide to carry out this experiment, make sure you record date/time and weather conditions, especially wind strength.
And please post your results to us, it may be very useful.
Firstly, please accept my apologies for taking so long to reply. Family duties took precedence. Anyway…
At one point early in this study, an acoustics specialist took a record of the Noise and developed a spectral analysis. Unfortunately, this blog will not let me attach it. It shows peaks at 100Hz, 200Hz and 300Hz with the strongest being the lowest frequency and the weakest being the higher frequency. There are no discernible peaks beyond this. The 100Hz peak lies at +20 dB (no mention of A or C), the 200 Hz peak is at 15 dB and the 300Hz at 3dB. A time plot taken over 3 minute period shows overall noise between 25 dB and 45 dB with peaks to 75 dB. I wish you could see it for yourselves, but it cannot be added.
These peaks indicate main electric supply issues, recalling that here in the UK mains electricity runs at 50Hz and not 60Hz as in the US and elsewhere. UK Power Networks, the organisation responsible for delivering electricity to us, have been very helpful. They have analysed the supply over a one week period and have found that the supply is within specification. They also disconnected the house completely, that is all wires including earth removed: there was no change in the Noise. This would suggest that the Noise is not borne on the electricity supply, but arises from something else.
From the above:
2. Does anyone have ideas for equipment that will record and analyse the Noise?
(1) Agreed that it is (probably) not the traditional Hum. From now on, it is named the Noise. Actually, it may be useful for the future to differentiate between the traditional Hum and what I now call the Noise.
(2) The house is in a very quiet area. The Noise is predominant at all times of the day – unless the wireless or television is on. The recordings have been taken late in the evening when no other sounds were heard.
This Noise drills into our heads. It could be used as a form of torture, as it is pervading and almost sounds as if it is in our brains. Please help us to determine the cause and cleanse our house of this dreadful Noise. For the local council to act, they need to (a) hear it and (b) know the source. It then becomes a “nuisance” in law under the UK’s Environmental Protection Act and can be stopped. Hence the need to record it and to find out where it is coming from.
Incidentally, the transformers are around 200 yds from us and have been tested by UK Power Networks and found to be working correctly, so that is not the cause. There are no main power cables under the house, which was built in 1825 (not old in the UK!). The drains run away from the house to a pump that is 1/4 mile away. Water into the house is pumped from a pump 200 yds away, but that would be on demand and not functioning all day and all night.
There are two pubs around 100 yds away. They have coolers for the freezers and drinks cabinets and fans for the kitchens, but these would also only work on demand or are switched off at night, so they cannot be the cause.
Other than that, I am not sure where to go or what to do. Ideas, anyone?
(With apologies for the long post, but it needed to be said)
Send me the files, and I’ll upload them (email@example.com)
I posted those audio spectrum shots here: https://drive.google.com/file/d/1A1GLWaaJq-TkUbCX5vP_s81nfOF4yLSW/view?usp=sharing
Outstanding! Almost certainly it is originating in your 50 Hz power mains. If this were directly from 50 Hz, you would find 50 Hz, 100 Hz, 150 Hz . . . in the spectrum. But like many (most?) power hums, it is all even harmonics (100 Hz, 200 Hz, 300 Hz . . .). This is because what you are experiencing is full-wave rectified (absolute value).
As a radio “ham”, you are quite familiar with full-wave rectified (FWR) power supplies, so understand the even harmonics in terms of the Fourier series. Most importantly, it does NOT seem to be FWR supplies (or 100 Hz hum picked up in a stereo system) because you turned off the power with no change. So that’s out.
But you likely have a FWR form of acoustic noise. This would be a 50 Hz electromagnet (a transformer) vibrating a steel equipment panel (or similar). If the object responding to the transformer’s (bipolar) field were A MAGNET, it would vibrate at 50 Hz, attracted and repelled once per cycle. On the other hand, if the responding object is merely ferro-magnetic, the transformer‘s field attracts regardless of polarity, hence twice per cycle.
You perhaps should search more carefully. Do your neighbors hear it? Are your supply lines underground or attached to an exterior wall? [ Even at 200 yards an overhead wire might transmit (longitudinally, and without much radiation) a vibrating transformer to your wall (like tin-can “telephones” on a string. ]
Good luck – Bernie
Is it just me or is this a little blurry? It’s smaller, too, than the original one.
If anyone else has the same issue, then I’ll take another go at it.
Now it looks fine.
Glen: Many thanks for uploading the file.
Bernie: Your remarks are very relevant.
Firstly, we live in an end cottage that is one of five joined together. There is an overhead power cable attached solidly to the outside wall and feeding next door. All the cables in the village are overhead, except for the two leading to our house and next door, which are both buried.
Secondly, listening to the internal walls using a stethoscope, there is more sound on the brick and flint walls that are founded compared with the stud walls between rooms upstairs.
My wife feels that there is more noise in the corner of the bedroom compared with the middle. This reminds me of a study that I undertook as part of a course at Southampton (UK) University where a lecture hall was set in resonance and I noted a greater level of sound in the corner.
I accept your view that this Noise looks like Full Wave Rectification.
Two opportunities come to mind:
(a) measure the rooms and determine their dimensions to see whether or not they are a whole number of half wavelengths in size, remembering that v=fl where v = 343 metres per second (1,125 ft/s) and f = 100Hz, 200Hz and 300Hz and l = wavelength.
(b) Get back in touch with UK Power Networks to see what they can do to prove or disprove the hypothesis.
I’ll report back once I have some further information to share.
Thanks to Keith for supplying the spectrum chart and to Glen for posting it.
(1) I might suggest that the obvious strong lines at 100, 200, and 300 Hz be compared as db measured DOWN from the strongest (100 Hz) and only to the noise background level. Referenced to the largest in this way, the three lines, as charted, are 0db, -5db and -17db. Measuring to the noise background gives 0db, -13db, and -18db. Either is wholly consistent with power mains vibration.
(2) The calculation of room resonances of a 3-dimensional room is a classic boundary-value problem that does not reduce to fitting half-wavelengths to individual dimensions. The result is, however, a simple equation noted at the very bottom here:
Click to access ENWN38.pdf
Online are many discussions (and calculators). Neither is it particularly difficult to measure any ACTUAL strong resonances, although good agreement with theory is not expected (rugs, windows, furniture., etc).
(3) It would be surprising if at least some of the local power folks were not familiar with the issues here.
In my checklist for hearing the traditional Hum (Inside Edition thread) I listed 8 items, number 2 being the rarity of the perception (2%), – – – as a diagnostic. Here Henrik makes a more significant point – that this rarity, being in evidence, any explanation in a theory of a source needs to address this: why do so few people hear it?
From looking at the Hum Map, I think we can conclude that the Hum distributes according to population density and roughly evenly by age. The heavy weighting of ambidextrous people is intriguing. One possibility is that there is a genetic predisposition which is triggered by certain modern environmental or other factors. That would explain why the Hum appeared when we (currently) think it did, and would also explain the even distribution throughout the population. I regret, very much, not asking about race, because we know that there are many medical conditions that distribute unevenly along that variable. Maybe before the Hum Map gets flooded with reports from Asia, we should consider that as well.
The version that I now access ends with the individual’s “head/brain”, but based on recent comments, shouldn’t it say”body/brain”? Wouldn’t that be more accurate? Or have I just not been able to access the correct version? By the way, it’s great to see this amount of activity on the site.
It is true that earlier versions said “body/brain”, but since it is very unlikely that any organ outside the head could produce a continuous low-frequency tone, “head/brain” is more to the point, mainly referring to the auditory organs and the parts of the brain that process auditory information.
My “Logic Map” does not in any way represent a consensus or even less the final word on anything. It is just one contributor’s attempt at helping us think clearly, which Dr. MacPherson found interesting enough to publish.
Thanks so much, Henrik. I also agree that your logic map is very helpful in the quest to find the source of the Hum. However, my thinking is this: if the source is internal, it may be premature to conclude that its source could not be, or include, a body part outside the head. By way of a hypothetical example, approximately 2% of the population may have an anomaly in their circulatory systems that, when interpreted by the brain, manifests itself as the Hum. I sure wish that we had the financial resources, and sufficient interest from the medical community, to take a deep dive into this research.
If the level is as strong as around 40dBc, you could try to find a small handheld recorder, Zoom H4n, which is commonly used by radio and TV reporters. Make sure you make any recordings with NO weighting (in the Zoom, the switch MIC LO CUT must be set to OFF [page 68 in the manual]). The recorder should preferably be suspended in a couple of rubber strings and not held by hand or placed on a tripod, to avoid recording building vibrations, your heartbeats and your arm muscle contractions.
The most common man-made noise sources are ventilation and air conditioning machinery especially in commercial buildings, underground water and sewage pumps, and diesel generators, often installed underground and bolted to the bedrock, which carries the sound for tens of kilometers (!). If you live close to a harbour, all ships have generators that must run 24/7. Etc. Good luck!
To clarify the apparent contradiction between Bernie’s reply above and mine: Bernie is right, 40 dBC is a very silent sound, which may be missed by many persons. My comment “as strong as 40 dBC” refers to the performance of the recording equipment. Low-noise electret microphones have a thermal noise floor somewhere around 18-20 dB, which means that a 40 dB audio still yields around 20 dB signal-to-noise ratio, which is more than enough for analyzing the signal and its spectrum. Note that in audio we use dBC (C-weighted), not dBc (referred to carrier).
Henrik – indeed
Here I believe you, me, and Keith basically suspect that Keith’s hum is some real acoustic vibration. I am assuming that Keith’s hum is nonetheless low in pitch, like the Hum (say 55 Hz). This is why I asked for his pitch match.
If he measures (+)40 dB-c-weighted (essentially flat down to 50 Hz) the human PERCEPTION of his level is going to be about an additional (-)40 db below (Fletcher-Munson) what a meter might read – thus about 0 db, or threshold of hearing.
Henrik: I have tried to use the Zoom, but have not been able to make out the Noise from the background. Noted about the difference between dBC and dBc. I meant dBC when I made the sound level record.
Bernie: All noted. I am a novice in this subject, so all very interesting. Also, I will look through the information on the website concerning room resonances.
All: I have had a response from UK Power Networks. They would like to confirm the hypothesis as being as follows”
– You believe that there is a mechanical vibration in the electricity network attributable to full wave rectification.
– This vibration is transferring through the overhead service cable to your property.
– The shape and structure of your rooms are such that they are amplifying the vibrations – much like a speaker would.
I feel that this is a good summary of the discussion to date. Would you agree?
Keith – thanks again. I think you understand this quite well.
– The “100 Hz hum” (Google that) from transformers is not new. With no particular effort:
“The basic cause of transformer noise is Magnetostriction, which is the expansion and contraction of the iron core (laminations) due to the magnetic effect of alternation current flowing through the transformer coils.”
“The fundamental sound frequency is twice the power line operating frequency of the transformer (i.e., a 50 Hz transformer produces sound at 100 Hz and a 60 Hz transformer produces sound at 120 Hz). In addition to the fundamental frequency, harmonics are also produced.”
The ability of an AC current to vibrate a metal plate at twice the current frequency goes back at least to the “snorker”, a code-practice device (remember those) based on a coffee can, a cigar box, a hacksaw blade, a short dowel, and a bolt wound with wire (and a resistor line cord). For years I have had lab supplies vibrate (me at 120 Hz), with the cure being an appropriately wedged rubber eraser.
Your power supplier’s engineers can’t possibly be unfamiliar with this.
– Again, the longitudinal transmission of sound ALONG wires is familiar (tin-can telephones).
– I suspect that room resonances are not a large issue, unless you have a particularly high-Q room (hard walls and no fabrics). If you have a very strong 100 Hz resonance, you can probably hear it as a damped response to a sharp hand clap (sounding like a “flutter echo”). To actually measure it, a function generator, loudspeaker, sound-level meter would be easy to try.
You are getting close.
Keith: If you cannot find the Hum in the recording by listening, try to make a spectral analysis to see if it is there. Also check what microphone type you are using and what its noise floor is. The Zoom is mostly used by reporters and for live music recordings at high volumes, where the noise floor is irrelevant.
About the UK Power Networks responses: I don’t think “full wave rectification” is a correct statement, since that would point to something in your house. The power grid does not contain any rectifiers. As Bernie pointed out, a better term here would be something like “transformer vibrations”, which have a fundamental frequency of twice the mains frequency, plus harmonics.
The second statement, that the sound is transferred via the overhead cable, does not match with your statement in your Feb 18 posting that your house is fed via an underground cable. Which way is it? And is the transformer you refer to pole-mounted or on the ground?
Bernie, you are a star!
There is a report on a doctorate thesis that proves the point at the following URLs, the first being a short-form of the second.
Click to access FULL_TEXT.PDF
Click to access datastream
These links give nice explanation.
(Sorry. I don’t know how to convert these to executable hyperlinks in the blog)
Our configuration consists of a transformer that is mounted on two telegraph poles. The cable passes around the common (an open area of grass) on telegraph poles with overhead take-offs to each house. These overhead cables are solidly attached to the outside walls. Our house is one of five cottages that form one building. Our cottage has a three phase cable underground from the nearby telegraph pole. Only one of the phases is used. The other cottages have overhead cables, one of which is attached close to the party wall.
Following your analogy, the noise would not be conducted through our underground cable. This would suggest one solution, that of removing the overhead cables attached to the cottages and installing a connection to each cottage from our three phase cable solidly attached to the wall. Whilst this might satisfy our problem, I shall be asking UK Power Networks to investigate the transformer as well to see if the issue can be sorted out at source.
Does that make sense?
My husband had a question after I sent him one of the links above:
Do transformers hum more (or at lower frequency) when the power usage is less? If so, that would explain why the hum is louder at night. Less power is drawn from the grid while people sleep. You might ask this on the forum.
Transformer hum frequency (analogous to musical “pitch”) is fixed at TWICE the supply frequency (2 x 60 Hz = 120 Hz, or 2 X 50 Hz = 100 Hz), regardless of load. I would suppose that the hum’s amplitude (analogous to musical “loudness” or audio-system “volume”), would, if anything, decrease with decreasing load. Noisy transformers may more generally be regarded as “abnormal” in various ways (aging lamination glue, etc.). Apparently being louder at night is probably due to nighttime relative quiet.
Hi Bernie, regarding just your last sentence that the hum is louder at night due to nighttime relative quiet, I can say without any doubt in my mind that the hum is actually much louder at night here. It is often very quiet during the day and I do hear the hum but it is much softer. With the same amount of ambient noise the hum increases in volume after 10:00 or 11:00, and sometimes later. I am 100% sure of that. I think this shouldn’t be ruled out unless and until we know it as an absolute fact.
Lisa – you said: “….With the same amount of ambient noise the hum increases in volume after 10:00 or 11:00, and sometimes later. I am 100% sure of that… ”
Really – isn’t this all relative and subjective – so how are you 100% sure! If you are talking about such things as transformer hum and road-traffic noise (real, measurable audio) than do you have metered sound-level data? If on the other hand, you mean “the Hum” then no one has ever been able to measure/display/record that. Please elaborate.
Bernie – When the noise in my home and neighborhood is the same during the day as it is at night, and the hum is sometimes barely audible during the day but so loud at night (at times) that it makes it difficult to go to sleep, it doesn’t seem too reckless a thing to say that the hum gets louder at night. I can’t measure the hum, but I trust my ears. If someone is going to assert that the hum is the same volume day and night, I would think it would be incumbent upon that person to prove it, since that contradicts what my senses are telling me. If it could be proven that it doesn’t get louder at night and it only seems to be louder to me, then I would have to believe it, obviously. But until such time as that happens, I am going to trust my own ears. Since there is no way to measure the hum, neither of us can prove that it does or doesn’t get louder, so maybe both positions should be on the table until we know for sure what the truth is on the matter. Beyond that we’ll just have to agree to disagree, I guess.
Incidentally, I have the water heater in my house connected to so called “night power tariff”, and each day randomly at 10PM, 11PM or midnight a relay in my power panel slams on (loud bang) and stays on till morning around 6 or 7 AM. This relay or contactor actually contains an AC magnet, which adds another 100 Hz hum, just like from a transformer. It is clearly audible if I go near, but the location of the power panel is such that it does not disturb our sleep. If it would be near my bedroom it would surely disturb me. Could that be what you hear?
Hi Lisa –
You asked about transformer hum, and why it might be louder at night. I said that it (transformer noise) would likely not be louder at night, but it might seem RELATIVELY louder. You responded that you had the same “ambient noise” before and after 10-11 PM, [and just now say it is the same day and night (always?)]. Since this is an extraordinary claim, I asked if you had actually measured it.
For me, my Hum SEEMS louder at night. Also, my refrigerator SEEMS louder at night; I assume it’s not. I am quite sure ordinarily environmental living sounds (like traffic) are generally louder during the daytime, and to a significant degree mask any internal or external hum. [ Daytime machinery hums mistaken for the Hum (like real trucks) are actually louder during the day of course.] The Hum seems louder at night at least in part due to masking. But loudness judgments are of course relative (logarithmic – in decibels).
Sometimes my Hum seems louder than other times; perhaps for a day or so. Sometimes I hear it during the day quite well. Sometimes at night – not very loud. At any time, if I intentionally “hear it” (shutting down distractions if necessary) the loudness seems well within a normal range regardless of time of day, and allowing for residual masking. Even a weak modulation by time-of-day-masking leaves a false impression of a 24-hour cycle that does not really exist.
That’s all I am contending about what I myself hear.
Henrik – Our water heater is in a storage room at the end of a hallway and the bedroom is to the left of it, so if that was the cause of the noise being louder at night I would be aware of it. To my ears the noise that I hear during the day remains the same except that it increases in volume as the night goes on (more often than not). It mostly sounds like a constant drumbeat. Because it only varies in its intensity and not in substance, I assume it’s the same noise coming from the same source. On the database here many others say it is louder at night so the question remains, it is actually louder or not? I think it is but if I’m proven wrong then I will be glad that we know for sure. I only say that we should be open to the possibility that it does actually get louder unless we know for sure that that isn’t the case. I am talking about the general hum, not specifically a transformer hum.
Bernie – Why is it an extraordinary claim to say that ambient noise can be the same day and night? I live in a quiet neighborhood. If the TV is off, if the lawn service isn’t here doing work outside (they are only here on Mondays), and when a plane isn’t passing overhead, it’s quiet. I don’t know what’s so odd about that. I live in a neighborhood with mostly retired, quiet people. And it doesn’t get quieter at night because it’s already quiet.
I reread both of our posts and realized that I should have specified that the hum in general, not a transformer hum in particular, is louder at night in my house. I don’t know where the hum is coming from – that’s what you all are trying to figure out, right? But we don’t know the answer to that yet. We
were talking about the transformer hum and I jumped to the general hum, so that was my mistake.
It does not matter where the water heater is. The sound would come from the electric distribution panel, if this would be the cause, not from the water heater. Anyway, my idea was just a long shot since you mentioned that “the hum increases in volume after 10:00 or 11:00, and sometimes later”, and that is typical for the randomized switch-on times of a night tariff service.
To me it begins to sound like you suffer from the basic otoacoustic “Hum”, which is created in your head. That is typically perceived stronger at night. Please refer to Dr. MacPherson’s recently updated intro text on this website, and to the “modulating factors” in the logic map at the top of this discussion thread.
Henrik – Ok, thanks.
Lisa, did you not mention on another thread that the hum you hear was quieter over Christmas time? This coincides with my experience, and from others in South Africa, UK, etc. So how can this possibly mean the hum you hear is “created” in your head (as per Henrik’s comment)??
Jess, yes, that was me who mentioned that the hum was quieter over Christmas. I don’t believe for a minute that the hum is created in my head. One night when the hum was very loud my husband heard it and it was the same pulsing beat as I was hearing. If I needed proof that it was external, that was it, though I never thought that it was internally generated. Also, if it is internal I would think I’d hear it in all places and I don’t. Others are going to have theories as they try to figure this out; some will be right (maybe) and others will be wrong. It will be a process. In the meantime, my own experience is my guide, and my experience tells me that the hum is external and gets louder at night. I think everyone here is well intentioned, very smart and trying to figure this thing out, and I am thankful for that, but I can’t relinquish my own experience to the views of others unless there is indisputable proof that they are right and I am wrong. (My 93 year old mother with dementia just arrived at my house a few days ago for a 2 month stay so I have had my hands full getting her settled in, and didn’t have time to start another debate over internal vs. external.)
Sorry for maybe jumping to a conclusion about internal vs. external. If it is an environmental sound, it can always be recorded. That requires a sensitive audio recorder (using an electret microphone to avoid recording magnetic fields instead of audio). No weighting filters. Then run the recording through a spectrum analyser software to identify the frequency components. This can give a clue as to the source.
Environmental noises, which come from distant sources, can be stronger in the night through so-called ducting, caused by temperature inversion layers in the air near the ground (10-50m). This typically happens when there is little or no wind. If the noise comes from, e.g., a commercial or industrial complex some mile(s) away, that would also explain the phenomenon of the noise getting lower during Christmas and other holidays. Good Friday is often used for maintenance in commercial buildings, and is a good indicator to listen out for. Good luck!
Lisa, I’m sorry I misunderstood you. As long as we’re clear. I’m frustrated by an air of persuasion in a lot of comments here from a very few insisting on an internal source. A criteria has been constructed by these few as to “THE typical hum”, which I find rather odd, let alone limiting. If a person does not fit this particular criteria, then they are told they’re not hearing “THE hum”. Many true hearers may feel alienated and discouraged by this and refrain from commenting about their own experiences. According to the database controlled by this site, there are many thousands of hearers but, no doubt, many thousands more who have not filled in the questionnaire. I agree that everyone will have there own theories and experiences, but we need to hear about them and not be turned away or discouraged if those ideas do not fit a criteria established by very few.
Quite true, but this is also an academic exchange, which can sometimes feel like an adversarial setting. I am directing my energies toward otoacoustic theories right now because I think they make the most sense given the data I have. But anybody here, within some limits, is free to speculate, debate, and even conduct independent research. All discourse on this site must in good taste and must be respectful. So feel free to post! Glen.
Henrik, thank you for that explanation. I will be very curious to see what happens on Good Friday. Do you know if the type of recorder you mentioned is sold commercially, and if so, if it has a specific name? If not, what kind of professional might use such a device ( ie, a sound engineer)? The nearest big city, Charleston, SC, is two hours from where I live so finding such a recorder could be challenging, but I’d like to try.
In the 200-300$ range there are a number of recorders like Tascam DR-40 or Zoom H4n, which are used by reporters and videographers. The serious, calibrated stuff is called Sound (or Noise) Level Recorders 500$-3000$. Maybe you could rent one. Ask around in electronics or audio equipment shops. The important things are that all weighting filters must be possible to disable, the microphone(s) must be electret or condenser type, and the inherent noise level must be as low as possible, since what you hear is close to ordinary people’s hearing threshold.
Thank you, Henrik, that is very helpful. When I have a chance I will look into this.
With people talking about recording/analyzing the Hum, it seemed appropriate to mention the MANY pitfalls of trying this. It turned out so complicated I wrote a webnote for any person considering investing time/money.
For example, there may be nothing acoustic to even record. Or if a
hearer does believe he/she has recorded the Hum, and hears a Hum during playback, how do you make sure it is from the recording and not a new live spontaneous overlay? That sort of thing.
Click to access ENWN54.pdf
Bernie, do you have any theory/ies as to why the Hum isn’t heard in certain parts of the world, such as the Yucatán? Thanks.
After lots of discussion, we have concluded that we have man-generated noise, rather than the hm. Having tried to record the noise using both the Tascam and the Olympus, there are a couple of point that should be considered.
1. Frequency Range. Most recorders are designed to match the human range of frequencies. Our noise is at 100Hz and 200Hz, which is at the very lowest end of this spectrum. This means that the recorder doesn’t record it well. (For aficionados, this is A-weighting).
2. Front-end Noise. All pre-amplifers contain components that generate internal noise, unless they are specially designed to do so (and are expensive). If the sound that is heard is not strong, it can be buried in this noise.
We were hit by both of these! I am designing a way around the problems, but am not certain yet that it will work. Fingers crossed….
Bernie, yes, I agree with what you’ve said, but it’s worth a try (I already bought the Tascam recorder). More important to me is that a woman who lives about five miles from me and heard the hum in her home in 2013, came over my house last week for the first time and heard the hum! It wasn’t loud, but I could still hear it, and she did too. She is the first person, besides my husband who heard it on one occasion when it was extremely loud, who has heard it besides me so that was a big deal. She is a business woman in our town, respectable and very sincere so I have no reason to doubt her. And her description of the hum is the same as mine and everyone else’s on the database here. I will still try to record it when it gets loud again but have realistic expectations about the outcome.
Harvey at 7:26
Are you conflating “isn’t heard” with “not reported”?
Reports are of course concentrated in areas of high population density and high internet use (and perhaps time to spare!). It’s just statistics.
Ah. Are you rejecting the notion that there may be areas where the Hum is actually not heard? I raise this issue because I vacationed in the Yucatan for 11 days in February and did not hear the Hum. When I returned to Vancouver it was also silent for 2 days before returning on the 3rd day. Just wondering if you have any theories to explain this. Or are you saying that my experience is not consistent with actual Hum hearers?
Keith at 8:57 AM – you are quite correct.
Henrik warned above “ . . . . The important things are that all weighting filters must be possible to disable. . . .”. If a general audio recorder does indeed use only A-weighting it would be fairly useless for recording hum. For those unfamiliar with weighting, see, for example (just the graph):
Click to access AN357.pdf
for the A- and C- weighting curves. Keith I assume that the excellent spectrogram you submitted was recorded by the power company on better equipment.
However, it did jump to my mind that human low-frequency response being as “bad” as it is may be A FACTOR in so few people (2% ?) reporting hearing as a habit of never being “challenged” to pay attention down there.
Harvey at 8:42 –
Thanks. Actually, your case (travel and return) seems to be a very useful data point pertaining to the notion that “The Hum” is interrupted for days or weeks following air travel.
Please keep in mind that with regard to statistics and timings here, we are not talking precise numbers, but general indications.
Thanks, Bernie. Of course, there is also the possibility that there are no recorded Hum hearings in the Yucatan because the Hum is not perceived in the Yucatan. There is no evidence yet that would negate that possibility, is there?
Jess, I hear you, and I have felt the same way. I know that some people believe that the hum is internal, but it doesn’t mean everyone has to agree with them. I don’t, and I suspect many others don’t either. If it’s internal it will have to be proven. In the meantime we are all in this together, and we all have something to say and should be able to express ourselves and feel supported by this community, so I hope you and others will be more vocal on this forum. All of our voices count, and as long as everyone is respectful, there shouldn’t be any problem.
It seems clear that in addition to a traditional, well-defined “Worldwide Hum” (“The Hum”), there are many varied, distinct, and mainly localized (and likely prosaic) pretenders that confound our study. “The Hum” is classically the sound of a diesel truck up the block – it follows the hearer over vast distances, is very rarely heard by others in the same room, and can be ever so briefly interrupted by a headshake. The Hum is never recorded/displayed, so a “real” (acoustic) component is unknown. A source is never found. Perhaps 2% of the population hears it, and of the comments posted here, VERY roughly half seem to exactly involve The Hum.
Pretenders – real trucks, generators, pumps, transformers, etc.- (roughly the other half of comments), have varied characteristics that are not usually very similar to those of The Hum, often leading to unwarranted confusion and conflict. In such cases, there is probably a “real sound” that is localized to a house or neighborhood (does not travel with the hearer), is NOT interrupted by headshakes, and IS heard by several – most everyone in a room. Happily, such menacing sounds are also rare, and potentially their localized sources can be identified and remediation seems possible. Evidently, a Hum Hearer WOULD ALSO HEAR any local pretender overlaid, thereby confounding any investigation. This is particularly true in that while The Hum has become standard, the manifestations of pretenders are diverse and each potentially unique.
To suggest that an observation is inconsistent with a mainstream version of “The Hum” is NOT at all suggesting a personal failing! Who wants the Hum! (Rather it is likely good news that a remedy may be at hand – in that case.) Neither should an individual insists that any of his/her personal observations (from a pretender camp) that are at variance with the mainstream Hummer checklist means that the vast majority of such traditional Hum hearers are misguided (or arrogant). To some extent, likely we are all dogmatic, but let us also be aware of the apples/oranges issues. Is there even an agreed-upon checklist? Here is an attempt, revised and posted as a WebNote:
Click to access ENWN53.pdf
Bernie, to whom was your last message directed? If me, I believe it was misdirected. It seems to me that there could be 4 reasons for the fact that there are no reports of The Worldwide Hum from the Yucatan:
1. Hearers do hear the Hum in the Yucatan but no Hearer has filed a report;
2. No Hearers have travelled to the Yucatan;
3. There is something about the Yucatan that prevents Hearers from hearing the Hum;
4. Air travel interferes with the Hum, and it takes more than 11 days (at least in my case) to begin hearing the Hum after air travel to the Yucatan.
My simple question was whether there is any evidence to support or refute any of these possibilities.
Thanks for your thoughts on this, Bernie ( or Glen, or anyone else.)
Harvey at 5:09 PM Thanks – In response to your 1 – 4
1. Can’t guess about what is heard – you are correct there are no reports.
2. Well, you traveled there! And hearers would logically also be born there.
3. Very unlikely. You can easily find other medium sized areas that are dot-free. All of Cuba for one example. Nothing (based on the map) remotely special about Yucatan.
4. I have seen reports of air travel interrupting for “days or weeks” and even surface travel through mountains having an effect.
In general I would suggest: (WAY!) Insufficient Data ! – Bernie
Yes, Bernie, regarding #3, I agree that is unlikely. However isn’t it also unlikely that roughly 2-4% of the population would perceive a noise that the rest of the population does not perceive. My point is that all possibilities should be left open until reliable evidence proves otherwise.
Harvey at 9:31 AM you said:
‘…. However isn’t it also unlikely that roughly 2-4% of the population would perceive a noise that the rest of the population does not perceive. . . . “
Not at all. First, you say “noise” as though it is a “real acoustic sound” (in the air for everyone); which it probably is not. “Hearing” the Hum may be a special talent, or an affliction, both of which may well be rare.
You also said:
“…. My point is that all possibilities should be left open until reliable evidence proves otherwise.
ALL POSSIBILITIES! Actually, isn’t it the case that all possibilities should remain CLOSED until at least a modicum of logic and scientific analysis (let alone reliable evidence) is put solidly in play?
But I am not sure what exactly your concern was. Exactly what is (was) the issue? -Bernie
Bernie, I don’t disagree with your description of the Hum. And I firmly believe that the cause/origin is partly, if not wholly, internal. I actually offered that opinion on this Blog quite some time ago. Just based on my experience of not perceiving the Hum while in the Yucatan for 11 days, and apparently no reports of the Hum from the Yucatan, I suggested that there may be something in the Yucatan that interferes with Hearers’ perception of the Hum. I have no doubt that I am a Hearer, as my experience is completely consistent with what has been described. Although the possibility is unlikely, it is not 0, so there may be value in pursuing this possibility. Such research could help determine whether the Hum is completely internal or the result of both internal and external factors.
Can we define noise, hum, etc., as a “perception of sound available to the conscious mind” for the sake of this discussion?
Harvey at 1:44 PM – Thank
My view I think is clearly stated: that there is a phenomenon called “the Hum” that is almost certainly completely internal to the individual hearer (including Glen, myself, probably you, and perhaps half those commenting here who know this Hum quite well. For us, there is no actual sound in the air around us. I provided a “checklist” of eight items as my Webnote 53 (see above). Probably the best evidence in this regard is the personal ability to interrupt the Hum with a headshake (etc.) or by air travel.
At the same time there are myriad real hums due to fans, motors, power equipment (such as Keith above has so well investigated) that IS a real sound, which aside from their low frequency and low amplitude and other evasive characteristics should be identifiable. Please see the Webnote 54.
You said “…..I suggested that there may be something in the Yucatan that interferes with Hearers’ perception of the Hum…..” You also said “…..Yes, Bernie, regarding #3, I agree that is unlikely…..” But according to the theories you seem to favor this would have to be something affecting the indigenous population at all times, infecting you on arrival, and following you home for two/three days.
Lisa at 2:25 PM
In order to not confuse engineers, probably “noise” should be reserved for a random signal and “hum” for a periodic one. For example, the human voice: the consonant sounds such as f, h, k, and s are noisy while the vowels are hums. And – the Hum may well not even be a proper sound!
Yes. I agree that the Hum is PROBABLY completely internal. But if there is any possibility that it is not COMPLETELY internal, that possibility should be investigated rather than discounted. I don’t understand the opposition to this suggestion. All for now, and I appreciate the opportunity to contribute.
Perhaps there could be a test to be used in determining whether it is The Hum or a man-made Noise, such as we have. If The Hum is internal, it would not be possible to detect and record it with standard environmental instrumentation, whereas noise should register on a sound meter. Our Noise can be seen on a sound analyser on an iPhone!
May I humbly ask all to scroll back to the top of this discussion? The very purpose of the logic flow map was to illustrate that all reports about a disturbing “hum” belong to one of two types, and to give some help in tracing which one people are hearing.
The first common denominator is a perception of a continuous low-frequency periodic sound, often having a certain rhythm or periodicity, i.e. “modulation”, of 1-2 Hz repetition rate. That has given rise to the common description “idling (diesel) engine”.
The second common denominator is that in most cases no other person in the same place and time can hear it. That is either because what they hear is internally generated (= cannot be recorded), or they hear an environmental sound because of exceptional auditory sensitivity.
All environmental sounds can be recorded with sensitive recording equipment and can be cured either by attenuating the source or using various measures at the receive end. Every case is different, and no universal remedy can be prescribed or designed.
What we are really focusing on are the internally generated otoacoustic or “somato” sounds, which may or may not be triggered or caused by external factors, as shown in the upper part of the logic flow map. The revised Hum report format aims at separating these cases from the probably much more common environmental noise cases. Only when we find the mechanism(s) controlling this internal phenomenon can we have a chance of finding a possible remedy for it.
It is not productive to split hairs about what is “The Real Hum”, since at the reporting moment the sufferer does not know the cause.
Henrik. Thank you for your clear and concise explanation. It states the two cases very accurately and allows everyone to determine into which category what they hear fits.
Indeed, I agree completely that Henrik has correctly identified the two possible conclusions of a conscientious reporting of a hum experience: an internal process (a “low-frequency tinnitus”) or a real acoustic buzzing from the external environment (various real motors, transformers, etc.). These are the very top line and the very bottom line of Henrik’s map, respectively. The same two cases are the subject of my two detailed Webnotes:
The Webnote ENWN-53 provides a “checklist” for eight items for the internal case. These eight tests are generally easy, no equipment required, instructions. Basically, a failure to “pass” one or more is an indication that the cause is NOT internal. In that outcome, effort can thereafter be concentrated on finding an external cause.
Finding an external cause may be simple, and may even fall out of the internal checklist test items. [ For example, you might fail the checklist in that five people in a house all hear a hum, and two of them then remark that it actually seems to be coming from a power pole transformer two houses up. ] Or – the external source could be very hard to locate, and require expensive and unfamiliar equipment.
Failing test items of the internal checklist is good news in that an external source and possible remedy is indicated. If the external tests (equipment) also fail to detect/display/identify any suspect real sound, can you be sure it is absent, or is it just beyond the equipment’s capability and lost in background noise (like traffic)? Problem! The human ear is perhaps the best detector, particularly as it can form a perceptible signal based on a set of weak harmonics, and as we may practice using various online tone generators at low pitches.
I have looked at the chart and can see that this might be the case for some people but this is not the case in my situation and doesn’t follow those flows.
Do I hear it all the time? No
Do I hear it a different locations? Yes
Can I feel it? Yes
Can I block the sound? No
Does that sound ever stop at location you hear it? Yes
Every time I travel I listen to see if I can hear it. I have been all over the USA and only a few places I could hear it and that was nice. My home its loud and I have looked at all sources that could generate it. I live in the country and its so quite if you hear anything you better investigate. The only thing I hear is an airplane at 3am that has a reciprocating engine.
The reason I am even here tonight is because it was very loud and I can feel it thru my body and can not sleep.
Anyone would like to find out more you can email me.
Lance, If I understand your description correctly, what you intermittently hear and feel is a rumble, not a steady low tone. This falls a little outside the conventional “Hum” description, and points to muscle contractions in the inner ear, apparently accompanied by other muscle tensions, since you say that you “feel” it as well. Maybe you should discuss this angle with a doctor, and maybe ask for some muscle relaxant medications.
Some people, including myself, can at will create a “thunderstorm sound” in both ears at any time by slightly playing with the inner ear and neck muscles. I am not a hum sufferer myself.
This case does not 100% fit into the chart above. The nearest would be the top box under “Individual sensitization”, possibly triggered by medication or some other external factor.
I wonder if the measurement tools most of us use (ie, cell phones, recorders) are sophisticated enough to pick up all possible sounds. My cell phone has not picked up the hum but that alone doesn’t convince me that the source is internal. I’m not saying it isn’t, only that I don’t trust that my cell phone is necessarily an adequate instrument for this purpose. I don’t hear the hum as much as I used to and when I do it’s never as loud as it used to be. Why the hum changes over time is a mystery, too.
Colleagues, as a medical doctor, scientist and engineer I applaud your efforts. An external hum is merely external. An internal hum can be pathological, however it may also represent neural activity, primarily in the beta (13-30 hz) and gamma range (30-80 hz) as measured by EEG. The more exciting part, is what this actually represents.
I explored this possibility roughly five years ago, via this fascinating paper: https://digitalcommons.northgeorgia.edu/cgi/viewcontent.cgi?article=1049&context=papersandpubs. The problem, of course, is that we don’t have access to such technology. One question that also remains is, why did the Hum arise in the latter half of the 20th century? If the Hum is simply an artifact of neural activity, what changed in neural activity leading up to that period?
There is no sound evidence (no pun intended) that the Hum is a
I’m a little surprised by that assertion. I’m seems to me it makes more sense to go with what we know rather than what we don’t know. A small amount of historical/media background suggests that the Hum became prominent in the late 60s to early 70s. There may have been a few isolated reports from earlier years, but if what you write is correct, then you should be able to establish that the Hum was here during earlier times. I look forward to reading that.
I too suspect that the hum has been going on for many thousands of years and has been only recently widely noticed/reported thanks to the ubiquity of the Internet; enormous (many more orders of magnitude) quantity of information, a place to report strange observations, and associated ability to painlessly search that data.
How many similar things were not commonly known-of prior to the Info. Age (also approx. mid 70s)?
From the beginning of this project, we realized that an accurate timeline of the phenomenon would have a massive influence on our thinking and the direction of the research. And perhaps I should point out that tinnitus has a long medical history (although it has escalated in modern times), whereas the Hum does not, at least insofar as I’ve been able to find it. Recall that several times per year I and occasionally another person dive into historical newspaper archives – in particular the Times of London back to around 1800 – in search of any unexplained sounds or noises that might meet our current descriptions. The only thing I’ve found are several intriguing references to the “huge swarm of bees” noise. I have asked many times for help in this over the years, but so far nobody has come forward. If we could confidently infer that the Hum has been around for a long time, then that would give great momentum to our working hypothesis.
For a fair number of years we have been here investigating “The Hum”: (A) a low pitched rumble, pitch-matching to perhaps 30-100 Hz, (B) occurring largely 24/7/365, everywhere, when otherwise quiet enough, (C) resembling a diesel engine idling in the distance, or similar, (D) being of no readily-apparent associated physical origin, and (E) being interruptible for about ½ second by vigorous headshakes. It is not likely a sound that is external to ourselves; being rather a middle-ear AGC (automatic gain control) mechanism. Anything else (non A-E) would seem to be something else.
Even today it is extremely difficult, even with numerous reports and real-time possibilities to follow-up (Internet), to get even a few clearly valid responses to conditions A-E. Such ambiguity most frequently suggests a phenomenon which is a “Real” sound. Would we not expect far, far less certainty from 200 year old newspapers?
Thanks for the Hum summary – it’s a good one. I’m uncertain about the newspapers’ certainty. One thing I know is that good newspaper reporting wasn’t invented recently, and therefore there may be a 150-200 year old newspaper article that describes our phenomenon. I think in terms of medical history, etc, the Hum should be documented as accurately as possible. There is also minor possibility that the Hum could have been responsible for some reports of the supernatural. That would be a minor victory for science, if we find that. Maybe I should ask readers to parallel process on this job for a few hours each, using creative search terms to comb the archives. Such historical research is not a high priority for me, and the chances of success might be low. However, I think it is a legitimate use of time, and the job can be sent out to folks who can to basic web searching. Cheers.
Glen – thanks
When searching old newspapers, can you suggest any useful search terms?
I can mainly only think of contemporary items.
Is there a newspaper section covering govt. boards that handle nuisance (noise) complaints? Complaining seems pretty universal over time.
Hi Bernie. I was all over the map on that one. I used very broad search terms involving “noise”, “sound”, etc, and then laboriously worked through them. I inferred some very interesting 30-50 year cyclic patterns in “hauntings”, etc, that I might explore at some point. Oh, and complaining about noise is indeed universal! I hope at least a few readers can dig deeper into the “huge swarm of bees” sound that had been reported several times over a 150 year period.
It may be useful to suppose ourselves in the position of someone 50, 100, or 200 years ago who heard something weird (like a hum in the darkness) and wanted to ask for an explanation. Real tough! I guess, lacking Google, one might ask friends/family, a teacher, or ”Andy”, as in “ask-Andy” (a newspaper column mostly for kids asking science questions – perhaps 65 years ago in my case). I assume similar features were a common offering at different times and places.
Often the questions were much better than the answers – but we only need to see that the questions were being asked, and if a column name for a particular local paper were found it might be at least an entertaining target.
Google “historic tinnitus sufferers” instead of hum and you will find yourselves way back in time.
And please don’t fall for high pitch ringing only.’ Tinnitus can be low frequency too.