I have to admit that I don’t even listen to or watch most of the media that I appear in. Frankly, the thrill is long gone and it can often be something of a chore now. I don’t really care who gets credit for solving the Worldwide Hum, but I do my bit by speaking with almost everyone who asks me to. A reader of this forum pointed me toward a segment near the end of the BBC4 Punt PI piece, which prompted me to listen to the whole thing. And I’m disappointed to say the least.
The audiologist Mark Williams spoke eloquently during his segment on the same BBC4 program where I also appeared. He is obviously an expert in audiology, but I think Punt PI intentionally conflated his work with tinnitus sufferers with efforts to investigate the Hum. He made no distinction between high frequency tinnitus and low frequency Hum. It should be noted that the percentage of people who report to the World Hum and Database who have tinnitus is roughly the same percentage of the general population who report tinnitus. Those who hear both tell us the two experiences are entirely different. We can’t tell from the BBC4 editing if Williams conflates the two in the same way the medical community has for so many years. In some ways I think the manner in which the BBC producers presented Williams’ research was a setback for the Hum community, and perhaps a setback for him. When Williams’ patient entered the “sound-proof room” and put on ear defenders, she emerged later, reporting that the relief from sound was “bliss”, and reported now hearing a “hum”. This is not even the classic behaviour of the world Hum. The listener was given the strong impression that the Hum was silenced, but this would be a huge overstatement.
Low frequency sounds and in particular infrasound can penetrate materials (and so-called sound-proof booths) much more easily than higher frequency ones. There is now evidence from high quality Soviet research that mining noises can penetrate three kilometres of rock downward, and at least 10 km horizontally along the ground (https://goo.gl/5p65ib). Moreover, it’s recognized that even though there is not a lot of variation in the perceivable frequencies of the lower-end of the audible spectrum, there is great variation in the activation thresholds of individuals, including a subset of the population who are vastly more sensitive to lower frequency sounds (references available upon request).
So we continue to correct the record, separate the variables, and look for more conclusive tests.
World Hum Map and Database Project 
This certainly does introduce new criteria, and thanks for remaining flexible Glen.
It brings to my mind two people from past posts on this forum.
First to Kurt, with whom I argued passionately against his thoughts on ELF sound, until he pointed out to me reliable data from worldwide shipping activity.
My apologies Kurt, your theory is looking better as time goes on.
Second, to Brian, who also has a leaning for ELF (both radio and audio) and who dared to declare our hearing ability a gift.
Your theory may now gain support, Brian, please post any new thoughts about our “gift”.
Thanx George, allways good with some passionate debate 😊
Do you happend to know how to find it, I would very much like to read it again.
Sorry Kurt,
I cannot remember the link you sent me, but I can recall the following information:
A friend of yours involved in ship engine production related how far the very low frequency vibrations generated by these extremely powerful machines can travel.
You then posted a link which showed a real-time map of worldwide shipping movements. That stunned me; I had no idea how many of these monsters are out there day and night, continually producing subsonic pulses of incredible amplitude, beating with each other, a salad of vibrations.
I commented about deep ocean troughs many kilometres in length, ideal conditions for the transmission of low frequency accoustic waves, and postulated on how subterranean creeks coupled to the oceans may possibly transmit those vibrations long distances inland.
That’s about all I can remember, and if I find the link I shall post it.
Cheers,
G.
Hello Glen,
Just a quick thought on the global population of hum sufferers(perceivers!).
While I agree there are similarities with tinnitus in so far as there’s no ‘obvious’ source of a perceived noise, I think that most of us experiencing the hum would say this is as far as the analogy goes.
Any true sufferer knows well from a multitude of different reasons that the ‘hum complaint’ has nothing to do with tinnitus and that it’s most definitely not something being generated ‘in our heads’ only.
While there are some who will dispute this “vehemently”, I guess they’re as entitled to their opinions as the rest of us and the very best of luck to them in their pursuits, but the majority of us are simply not ‘buying it’ and are looking for real answers here and are tired of getting bogged down with rotational confusion.
The facts from data you’ve collected just here (ie. personal reported experiences so far), strongly point to a majority consensus believing that this intrusion to auditory perception is being caused by something emanating from an external source.
Is this not majority rule and how a democratic process works?
True democracy by way of majority consensus as far as I’m concerned, should be more than enough to guide the direction and urgency of the research you are currently undertaking.
It’s also my opinion that you have now reporting to this site the ‘vast majority’ of global hum sufferers already logged.
I would hazard a guess that the low numbers coming back from China and Russia(et al) are simply the result of ‘extreme censorship’, but I’d say the numbers and percentages to be collected here are similar to the stats you’ve already accumulated.
I would say there’s a vast difference between global hum suffering percentages and tinnitus sufferers also, with those experiencing the hum being ‘significantly lower’ in percentages than those with tinnitus.
I suspect that beyond the censored and non democratic countries, what you have here, collected on the location map, is a definitive figure of global hum perceivers and I also predict that these stats will now only increase in tandem with ‘whatever’ form of technology that I believe “is” causing this intrusion to our auditory senses(or even perhaps at a much slower rate than this!).
With this in mind, could some ‘fine tuning’ of these statistics now be worth pursuing?
In this regard I ‘strongly’ believe demographics pertaining to religious/cultural background might be a significant statistic to be collected also.
It’s fair to say that the vast majority of the worlds population are all connected to a specific religion/culture by birth.
And I’m wondering if it could be possible that one religion/culture has a ‘significantly’ higher amount of ‘hum suffering’ than another?
(Eg. Say Christians 30% and Muslims 70% or similar?)
If data collected here strongly points towards one specific religion/culture over another, then I believe you now have something “really tangible” and potentially “highly controversial” to consider.
Just a thought….
But I would highly recommend you consider some way and some how of factoring this into your research as soon as possible.
Gerry.
I would add a personal experience to Glenns post. Two years a go I experienced low freq. tinnitus. Its not uncommon my doctor said, it went on for 3 days and then disappeard. I can most certainly assure you that its not the same as the Hum. Big difference as you also point out
I realise that different frequencies, variation in individual thresholds etc. probably all play a part. But if someone is exposed to low frequency sound which is above their activation threshold what do they actually experience themselves? Does it manifest as a higher frequency sound?
Do you mean above or below? I think you mean below threshold. If so –
Likely you will hear a higher frequency if the low frequency already had higher harmonics, or if it generates harmonics by clipping.
Take a plastic ruler and hold the first three inches to your desk, with 9 inches in free space. Displace and release the end. You can hear it fairly well despite its frequency being sub-audio. Better still, once it starts to vibrate bring your thumbnail up to the free end and hear the low-frequency impulse train as the ruler “taps” the thumbnail.
Probably you did this in third grade and your teacher did not recognize it as a scientific experiment!
The balanced modulator is just a pure and simple multiply. It is sometimes called a “double sideband” modulator, as opposed to a “single sideband” modulator, which is a frequency shifter. All are cousins of ordinary AM.
And it is as you say a “perception of the Hum”. I don’t see why it couldn’t be a pitch that is really a strong harmonic of an infrasound. But no evidence for that view either. We just don’t know.
I misunderstood what ‘activation threshold’ meant in this context. I [wrongly) assumed it refered to amplitude, as in for example, “If we increase the amplitude of a 10Hz audio signal it’ll eventually reach a threshold level which stimulates a physiological response”. To be honest I’m still unsure as to what the term ‘activation threshold’ is actually refering to here. Is it frequency dependant?
If I can hear the sub audio frequency of a vibrating ruler, does that mean that I could also hear a pure sine wave of the same frequency?
I don’t know what activation threshold is exactly either. I was thinking of a sinusoidal waveform that is below a threshold that is audible because it has harmonics that are audible.
No – you could not hear a sub-audio sinewave. Consider that if you snapped your fingers once per second (1 Hz) you would hear the snaps as isolated “impulses”. The ear has a “time constant” of roughly 50 ms which is 20 Hz and pretty much at the very bottom of anyone’s audible range. [The 50 ms time constant is seen across modes of perception. Recall that movies are 24 frames/second or 30 frames/second. A fly, in contrast, has a time constant of perhaps 2 ms, which is why humans need a lever (swatter) to hit one.]
It’s the harmonics (of an impulse train) that make the “buzz” audible. Eventually (perhaps 50 Hz) the impulses “fuse” into a single sensation of a particular pitch.
I didn’t really think that a sub-audio sinewave would be audible – mainly because it is by definition ‘sub-audio’. Which made me wonder why we can hear the sub audio emanating from the vibrating ruler.
But, if I read you correctly, it’s not the sub-audio component of the vibrating ruler that we hear, rather it’s the higher harmonics that it produces that we notice.
What i am wondering is that if the Hum is a sub-audio frequency how are we still managing to hear it. I have looked around and I haven’t found anything as yet which says that pure sub -audio (no harmonics etc.) can be perceived as regular higher frequency sound. (Other effects are mentioned eg. drowsiness, even vague feelings of apprehension.) But it’s a big topic and I’m still looking.
One big problem is we have not gotten a close look (or any look) at the Hum as a waveform. So we don’t know its spectrum, and the pitch is difficult to hear.
Keep in mind the missing fundamental. If we have frequencies f, 2f, 3f, 4f, 5f, . . . we hear a pitch of f, and if the fundamental frequency f is very weak or missing (or just rolled-off), we would STILL hear the pitch f QUITE nicely.
I recall someone insisting on 113 Hz (twice Glen’s 56.5 Hz, which could be a second harmonic). If this person also heard the third harmonic at 169.5, but not the fundamental 56.5, this person should have heard 56.5 anyway. For 56.5 to be unreported, 169.5 (the third harmonic) would need to be missing.
Now, Charlie, you got a best synthesis (reported on the “Volunteer …” thread), favoring a pitch of 63-65, using a mix of 63, 126, and 252. Can’t help noticing this is f, 2f, and 4f. Again no third harmonic. Coincidence?
High marks if you understand what I said here in English! Instead, take it as a recipe for making a sketch, which you can understand.
Perhaps nothing – but good exercise.
I didn’t try 3f in the mix because I didn’t think to at the time, I’ll go back and try again. Maybe I should experiment with higher harmonics 4,5,6f etc. as well.
You said if someone hears 2f and 3f they will get the impression that they can hear f (the missing fundamental) as well. Would that happen with a mix of 2f and 4f? ( I guess could just try that with the tone generators.) Are there particular combinations of higher harmonics that are better at producing missing fundamentals than others?
For me the fundamental 63Hz is very weak, the 126 Hz seems to predominate. But the hum is a complex sound (fuzzy) so I suspect that theres more to it than just a mix of harmonics. It also changes over time which complicates things if I’m going to try and recreate it with tone generators. Despite the changes though, the sense of ‘pitch’ (nf) remains the same.
But what I really wonder is how infrasound alone could be responsible for any of this?
Ahhh- good.
2f and 4f is 1*(2f) and 2*(2f) so it is a fundamental of 2f with a second harmonic (4f). You hear a pitch of 2f. It’s an “old joke” to talk about the pitch of a tone with only even harmonics.
[If you add f back to what is otherwise all even harmonics: e.g., f, 2f, 4f, 6f, 8f…. you will get a pitch of f. If the amplitude of f just goes briefly and smoothly through zero and back non-zero, the ear is fooled into not noticing it was gone and its f all the time (history matters). ]
As to the “fuzz” – I hear it too. No good conclusion. I think it is probably not noise, but a “buzz” of the harmonics. Remember the plastic ruler buzzing, perhaps at 10 Hz.. This was because the “impulses” were very low in frequency (harmonics close together, 10 Hz). If you try, for example a mix of 200 Hz, 400 Hz, and 600 Hz, you will hear an “edgy” (harmonically rich “oboe-like”) tone, but no buzz. So somewhere between 10 and 200 Hz, like where the Hum is, you hear not a buzz, not a smooth tone, but what you call fuzz. Well – that’s my guess.
In general, a dense set of harmonics above a missing fundamental is best. But you can add, for example, all harmonics from f to 16f and pull them out from the bottom, one at a time, You will continue to hear f as the pitch when only 14f, 15f, and 16f remain, (but not just 15f and 16f), and probably not hear f that well with just a few harmonics remaining if you do not lead-in with the “staircase” removal process. (Again – history matters!)
But what is infrasound? Clearly something like 5 Hz is and 500 Hz isn’t. Somewhere (like 50 Hz) is perhaps just a nasty mix.
Ok I get the part about 2f and 4f – cheers for that! It sounds obvious when you explain it – I feel like a bit of an idiot for not figuring it out for myself!
I’m going to mess around with the tone generators in a moment. The ‘history matters’ part is interesting – I guess this is from the realm of psychoacoustics. I’ll try turning off one of the mixes of higher harmonics for a while and then turning it back on again to see if my perception of a fundamental changes.
According to wikipedia, infrasound is sound that is lower in frequency than 20 Hz ( the same as sub-audio I suppose). As I understand it, one of the reasons it is a candidate for the Hum is its ability to penetrate materials better than higher frequency regular sound. If infrasound is the culprit it might explain the Hum’s ability to go through conventional soundproofing eg. earplugs etc..
But I don’t know how, or even if. sound that is below 20Hz can evoke the perception of a higher frequency sound, eg. the Hum at 50 – 60 Hz( or more). As i mentioned before all I can find is that infrasound might induce such things as poor sleep, seasickness and vague feelings of apprehension. I haven’t found anything (yet) that says that infrasound can produce the sensation of normal sound.
I can see that it’s possible to produce the perception of a low frequency sound from a combination of higher ones. Eg 2f and 3f producing the perception of f. But is the reverse possible? Is there any combination of low frequencies that can produce the sensation of a high frequency?
you asked: “But is the reverse possible? Is there any combination of low frequencies that can produce the sensation of a high frequency?”
Yes – but not by summation. If you MULTIPLY two sinusoids together (technically “balanced modulation”), you get sum and difference frequencies (see trig tables), Two problems: (1) if both are infrasound, the sum may still be infrasound, or very low audio at best. (2) what is the mechanism that multiplies (addition is easy enough). [What is called a “combination tone” is possible due to non-linearity, but the Hum, in general, is not loud enough to argue driving into a non-linear region).
Now, a sound that technically has a pitch (defined as a fundamental) that is infrasound could be audible (noticed as the sound being present) due to harmonics.
Thanks for all that Bernie.
I’ll have to look up balanced modulation.
If it is possible for an infrasound fundamental to produce audible harmonics, then I suppose its plausible that the perception of the Hum could be caused by some sort of infrasound.