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Earth's Constant Hum Explained
MattSparkes writes "It has been known for some time that there is a constant hum that emanates from the Earth, which can be heard near 10 millihertz on a seismometer. The problem was that nobody knew what caused it. It has now been shown that it is caused by waves on the bottom of the sea, and more specifically 'by the combination of two waves of the same frequency travelling in opposite directions.'"
Ohm-mani-padme-hum
When I'm in a quiet room I can often hear a quiet hum. It started after I went to an Arctic Monkeys concert...
Matthew Sparkes
I've always just assumed it was the Earth purring.
Nothing is impossible. We just haven't quite worked out how to do it yet.
The sound of the Earth meditating upon its naval should be a comfort to all of us.
--
Spelling, its only fun it you can mess with it.
For the love of God, make it stop!
The opposite of progress is congress
I had a constant 50Hz hum emanating from my loudspeakers once. Swapped the brown and blue wires going to the turntable and that cured it. Reckon somebody at the factory didn't understand that the live wire should be on the INSIDE of a motor stator or transformer whenever there is sensitive electronic equipment nearby. Of course, on the Continent, they could just reverse the plug in the socket with the same effect. What's worse is I've known someone wire a high-impedance (50K ohm) mic to a preamp with about five metres of unshielded cable, running in a bundle with mains cables, and not a hint of a hum. Go figure.
Je fume. Tu fumes. Nous fûmes!
That, or it is the power plant of an alien base hidden in the hollow shelf off the Vancouver coast. Or both.
= 100 seconds per cycle?
So all this time I guess I should have put the tinfoil in my shoes.
#!
...as Douglas Adams might have said.
All this time, I just assumed it was because it couldn't remember the words.
http://derkosak.blogspot.com - That's a blog.
I think this is a concept related to Pythagoras' Musica Universalis http://en.wikipedia.org/wiki/Musica_universalis. An inaudible sound on all celestial bodies.
I hate signatures
Ok, so the waves are making the sound. Now tell us what causes the waves. I didn't notice a source in TFA.
Just another day in Paradise
Your article was very interesting, but it's wrong. I have a better idea. You see, the center of the earth is full of bees. They make the earth hum and the turtle stack keeps turning to find out what's buzzing. You see? Mine's a much better explaination: explains the humming and the rotation of the Earth!
Demented But Determined.
It is probably driving the whales crazy. They think it's the Voices...
Nothing witty
Oh, which i should say is just another way of stating your correct calculation!
I have a degree in Mathematics... one would hope I had a solid grasp of fractions by now. But no....
Take off every 'sig' !!
When I shutdown my PC. Turns out the bearing was on its way out.
Task Mangler
there's some waves at the bottom of the sea there's some waves at the bottom of the sea oh there's some waves, there's some waves there's some waves at the bottom of the sea
is it a harnessable energy source?
I'm guessing it may be to week/dispersed. But would be nice to know if it could be focussed suficiently.
...the waves are making the sound.
Wait a minute. How do we know that it's the waves that are causing the hum, and not the other way around? Perhaps the planet is still ringing from meteor impacts, and the hum is just the resonant frequency. The deep ocean waves may be just a side effect.
When our name is on the back of your car, we're behind you all the way!
But the hum is a frequency doubling, the original waves would pass a fixed point at 18 per hour.
--
Wave mechanics surf.
10 milliHz is a beat every 100 seconds. Must be really tricky to detect. I wonder how far below that frequency the sensitivities of seismometers go.
e cording mentiones only down to 1Hz. Need to see original article in Nature from work.
http://en.wikipedia.org/wiki/Seismometer#Modern_r
I do not believe in karma. "Funny"=-6. Do good and forbid evil. Yours, Oft-Offtopic Flamebaiting Troll.
So that's the noise that has been driving me up the wall.
I always thought it was the Balrog humming.
These atheistic God-denying scientists attribute the constant hum detected by the seismometers to some random wave action at the ocean floors. But they ignore the fact that it violates the second law of thermodynamics (whatever it is). The real cause for the hum is the intelligent shaking by the Shaker. We demand equal time in all classrooms and seminars and conferences, wherever these surfologists congregate to rebut their theory (not fact) with our scientifically formulated real sceintific fact that intelligent shaking is the fundamental cause for all the hum on earth.
sed -e 's/Chuck Norris/Rajnikant/g' joke > fact
If this humming is omnipresent, it means that every music is "sampling" it without authorization. We then sue RIAA out of existence for unlicensed sampling.
PROFIT!
Nobody's figured out how to ground the dang thing.
Post may contain irony: discontinue use if experiencing mood swings, nausea or elevated blood pressure.
If I know which one maybe I can tune it to make music and really stump the scientist.
(re: my user handle)
Lex III: Actioni contrariam semper et æqualem esse reactionem: sive corporum duorum actiones in se mutuo semper esse æquales et in partes contrarias dirigi.
Actually the hum is the planetary ring down of the violent shaking the earth received after the continents rapidly moved to their present locations due to a global-scale flood tectonic cataclysm. BTW I predict that the magnitude of this hum is exponentially decaying just like the speed of light and earth magnetic field.
10 millihertz sounds more like a throb than a hum to me, perhaps even a chug.
Maybe we could build a clock that used this hum as some sort of synchronization. Then every clock on the planet could be synchronized, since this signal is presumably detectable everywhere.
:-)
OK, I didn't say it was a *good* idea
The more you regulate a company, the worse its products become.
Well many seismometers are constantly on and have very long periods of this noise recorded.
So with enough stacking you can pretty much detect as low frequencies as you want if only the amplitude is strong enough to be detected by the seismometers, so my guess is that the limiting factor is not the 1 Hz, but lies in how small amplitudes these seismometers detect.
These suggested waves would hold quite an amount of energy so it does make sense that they are able to detect these to me.
...you should have become an accountant.
Venkman: Exactly.
Ray: Fire and brimstone coming down from the skies, rivers and seas boiling.
Egon: Forty years of darkness. Earthquakes, volcanoes-
Winston: The dead rising from the grave-
Venkman: Human sacrifice, DOGS and CATS living together.. Mass Hysteria!
Now if only they could make the voices stop as well.
Does this fall under news for nerds or stuff that matters? I'm guessing it isn't the latter.
"I'll see you next time." - LeVar Burton
'cause apparently, B Flat is 'universal':y Id=7442915
http://www.npr.org/templates/story/story.php?stor
That was just the bass on my kickin' car stereo. I turned it down, so it shouldn't be a problem. Those nine-foot quartz drivers are tite!
But seriously, how much power would it take to put such a vibration into the air, and how far would it travel? I'm just picturing the hair on my head blowing this way and that way with the changes in sound pressue.
Never ask for directions from a two-headed tourist! -Big Bird
Maybe it just doesn't know the lyrics.
Read her post again, it wasn't a ground loop -- it was the motor. The live lead was erroneously connected to the outside of the windings. She swapped over the connections so the live was on the inside and the neutral was on the outside, thus shielding it.
what's driving the very low frequency waves then??? Atmospheric turbulence??? Which if so, would mean that the indirect cause of the "hum" IS atmospheric turbulence...
Donald 'Duck' Dunn: We had a band powerful enough to turn goat piss into gasoline.
100 cycles per 10000 seconds, what about that?
ALL THE WAY DOWN
intellectual property law is philosophically incoherent. it is your moral duty to ignore it or sabotage it
You SO win the prize for 'AC reply that is most obviously by the original poster, ever'
A winner is you!
Whence? Hence. Whither? Thither.
I thought Zappa had explained this one years ago.
To paraphrase DNA, "Maybe it just feels good about being a planet?"
--- These are not words: wierd, genious, rediculous
We're living inside an inter-galactic boy band.
Venus is the hot one and will turn out to be gay (natch, I mean Venus?)
Earth is the um, down-to-earth one - full of life.
Mars - the cold and distant one - always at war with the other members
Jupiter - slightly overweight - jolly
Saturn - Gaudy over-compensator wears lots of jewelry and rings - looks up to Jupiter
Hot headed Mercury - left in a huff to form his own band - his manager is the real star though.
Uranus was an asshole and left before fame came.
Neptune - always blue, committed suicide after what happened to Pluto...
Pluto? Well, Pluto was thrown out when it was discovered he never could sing.
Cake or Death? Cake Please!
The Spongebob Squarepants cartoon was accurate all the time when it showed that there ARE beaches on the bottom of the ocean!!! We now know for sure that they have waves and everything. Who need Atlantis? If we could only find Bikini Bottom.
It hums because it doesn't know the words.
May be it could be related to the noise of higher frequencies. I do not see a problem detecting amplitudes in the absence of that noise.
I do not believe in karma. "Funny"=-6. Do good and forbid evil. Yours, Oft-Offtopic Flamebaiting Troll.
it is the Devil mowing his grass
He got third post, not first post.
Slow Down, Cowboy! It's been 60 minutes since you last successfully posted a comment.
That should have been 2^15 and 2^16.
All objects have a mean frequency which in this example is causing the frequency that they are observing in the water. The frequency in the water comes from the planet's own resonance, or a harmony thereof.
Tesla noticed this and build a little tool which hit on the harmonic frequency and kept accelerating the oscillation with a device he built until there were "earthquakes" observed all around, and he had to cut short a trip to run home and turn it off. Indeed in manufacturing speakers you try to get this frequency down below audioble range as you don't want the speaker to resonate and alter the sound it's supposed to generate.
It's a very common mistake made by many when they observe a symptom (not realizing there is a real why behind it.)
Article reporting the milliHz hum in 1998
IDA (International Deployment of Accelerometers) used to detect the hum.
Article in Nature (1979) assesses if IDA can be used to detect very low frequency seismic data. Looking at the figure 1 of amplitude(?) ("MD counts" at Rarotonga station not shown on the current IDA map) I can see the aftershocks in 2 hour intervals after the Indonesia earthquake, but the subj frequencies could be detected only by obtaining the spectrum (Fig.2) at mHz range which frankly looks like white noise - irregular beats.
Most interesting figure is Fig.3 which shows the 0.43-0.52mHz of the _processed_ spectrum measured at six different stations around the world at Hour 25 and on. The Alaska station (CMO) has much clearer spectrum compared to the closest (?) RAR station.
All of it must have meant something for a seismologist which I am not.
I do not believe in karma. "Funny"=-6. Do good and forbid evil. Yours, Oft-Offtopic Flamebaiting Troll.
If our whole planet were vibrating at a constant frequency... it seems to be that there is a lot of energy in that hum... any way to harness this?
Sometimes the best solution is to stop wasting time looking for an easy solution.
Is this like in Spongebob where they lay at a beach and swim in a "lake" even though they are underwater to start with?
If you could reason with religious people, there would be no religious people
would like to welcome our new underwater seismic overlords.
I bow down to the hum.
"There's a hum in the bottom of the sea.
There's a hum in the bottom of the sea.
There's a hum, there's a hum.
There's a hum in the bottom of the sea.
"There's a wave on the hum in the bottom of the sea..."
Convert RSS to HTML - integrate webfeeds into your website
... that's just 2 milliHerz above the Brown Noise. Thank the lord for that.
Rachel: It's coming from Joey
Phoebe: Oh my God turn him off!
Summation 2
..I'll stop now.
I guess earth doesn't know the words to the song then.
I lost my sig...
Hmm?
I'd give my right arm to be ambidextrous.
FYI, this frequency is an E note 15 octaves below middle C (C5). Well below the perceptible frequency of the human ear (10Hz+).
Much like the note that black holes hum... 50-some octaves below middle C?
Letter
Nature 445, 754-756 (15 February 2007) | doi:10.1038/nature05536; Received 2 November 2006; Accepted 12 December 2006
The Earth's 'hum' is driven by ocean waves over the continental shelves
Spahr C. Webb1
1. Lamont Doherty Earth Observatory, Columbia University, Palisades, New York 10964, USA
Correspondence to: Spahr C. Webb1 Correspondence and requests for materials should be addressed to the author (Email: scw@ldeo.columbia.edu).
Top of page
Abstract
Observations show that the seismic normal modes of the Earth at frequencies near 10 mHz are excited at a nearly constant level in the absence of large earthquakes1. This background level of excitation has been called the 'hum' of the Earth2, and is equivalent to the maximum excitation from a magnitude 5.75 earthquake3. Its origin is debated, with most studies attributing the forcing to atmospheric turbulence, analogous to the forcing of solar oscillations by solar turbulence2, 4, 5, 6, 7. Some reports also predicted that turbulence might excite the planetary modes of Mars to detectable levels4. Recent observations on Earth, however, suggest that the predominant excitation source lies under the oceans8, 9, 10. Here I show that turbulence is a very weak source, and instead it is interacting ocean waves over the shallow continental shelves that drive the hum of the Earth. Ocean waves couple into seismic waves through the quadratic nonlinearity of the surface boundary condition, which couples pairs of slowly propagating ocean waves of similar frequency to a high phase velocity component at approximately double the frequency. This is the process by which ocean waves generate the well known 'microseism peak' that dominates the seismic spectrum near 140 mHz (refs 11, 12), but at hum frequencies, the mechanism differs significantly in frequency and depth dependence. A calculation of the coupling between ocean waves and seismic modes reproduces the seismic spectrum observed. Measurements of the temporal correlation between ocean wave data and seismic data9, 10 have confirmed that ocean waves, rather than atmospheric turbulence, are driving the modes of the Earth.
Observations of the normal mode spectrum of the Earth made in the absence of large earthquakes show a roughly constant level, except for a small biannual cycle with energy peaking in January and July, which is consistent with the most energetic storm seasons (and hence largest ocean waves) in the Northern and Southern Hemispheres, respectively3, 6. The modes appear as a series of lines between 1 and 10 mHz in spectra from quiet seismometer sites during days without large earthquakes (Fig. 1a). Above 10 mHz, distinct lines are not resolved and the Earth's hum is better described as propagating Rayleigh waves5. The many small earthquakes that occur each day provide insufficient seismic moment to explain quiet day spectra1, 6.
Figure 1: Seismic waves are driven by ocean waves at half their frequency.
Figure 1 : Seismic waves are driven by ocean waves at half their frequency. Unfortunately we are unable to provide accessible alternative text for this. If you require assistance to access this image, or to obtain a text description, please contact npg@nature.com
a, Vertical acceleration spectrum from a quiet site (BFO, Black Forest Observatory), redrawn from data supplied by R. Widmer-Schnidrig (available at www-gpi.physik.uni-karlsruhe.de). Normal mode spectral peaks (Earth's hum) lie between 1 and 10 mHz, and are shown magnified in the inset. The DF microseism peak is driven by ocean waves near 70 mHz, the hum by lower frequency ocean waves. The 'SF' peak is probably driven by waves interacting with bathymetry11. b, Ocean wave height spectrum from the shelf off Florida25. Wind wave spectral peaks vary, but lie above 0.04 Hz. The model infragravity ocean wave spectrum used in the forcing calculations is also shown.
High resolution image and legend (63K)
It has long been known that ocean waves drive the large 'microseism' peak
-Eric
SJW: Someone who has run out of real oppression, and has to fake it.
Explanation is another word for theory and theirs is yet another.
...the Earth's PSU fan?
:)
I'm so dissillusioned.
--- For a good time mail uce@ftc.gov
Guess that means the Earth can't sing.
Give a hand, not a hand-out.
They should test it by removing the the world's oceans and seeing if the sound goes away.
It is by the juice of the coffee bean that thoughts acquire speed, the teeth acquire stains. The stains become a warning
Mikey: Heh, if you hit the wrong note, we'll all "B flat!"
"It takes considerable knowledge just to realize the extent of your own ignorance." - Thomas Sowell
fascinating...
if this is supposed to be a new economy, how come they still want my old fashioned money?
Sonarman 2nd Class Ronald Jones: You see, sir, the SAPS software was originally written to look for seismic events. I think when it gets confused, it kind of runs home to Mama.
Commander Bart Mancuso: I'm not following you, Jonesy.
Sonarman 2nd Class Ronald Jones:Sir, I'm sorry. Listen to it at 100 times speed. Now, that's got to be manmade, Captain.
Set your phasers on "funky"!
Oh great, so this is the damn drum solo, and next up is some freak on bass for a hundred thousand years!
Eclectic beats from Leeds, UK
handmadehands.co.uk
You ignorant clod, any child knows that the bees at the center of the Earth are giant bees, and their wings beat at exactly 10 millihertz.
Bad gas. Those beans are AWFUL.
Someone have a link to an audio file of this sound? (Sped up to a human-audible rate, of course.)
Can we get a "-1 Wrong" moderation option?
10. Underground cave/rave scene with Neo and Morpheus at Zion was based on real life and we're hearing everyone stomping/drumming.
9. The Earth is secretly a member of a barbershop quartet.
8. The earth's crust is filled with "space worm" creatures like the one that almost swallowed the Millenium Falcon.
7. It's been over 3,000,000,000,000 years since the earth was brought in for an alignment.
6. It turns out that it's not the Earth but the Sun that is humming. No one has replaced its "old fashioned" magnetic ballast with an electronic one.
5. The Earth is actually ET's alarm clock and it's going off, but we can't seem to locate the Snooze Bar (although some people believe that it's West Virginia).
4. There is no hum, a bunch of scientists got together and took bets as to whether or not they could get us all discussing their imaginary hum idea.
3. The Earth gets crappy reception because the moon keeps interrupting our "line of sight" required by DirectTV.
2. No one told us, but apparently they've put a HUGE intergalactic superhighway right through out backyard and we're hearing the freight cars roaring by.
1. Mother Earth is a little lonely lately and is experimenting with her vibrating "lonely person device".
Tesla was basically a constant flood of ideas. His genius is that at least half of them were good ideas. His problem was that the other half were crap and even he couldn't tell the difference. That isn't really such a bad problem; his good ideas were so good that I overlook the crackpottery and will cheerfully praise him to the stars for his many valid contributions. What is a problem is that modern day crackpots seem to have appointed him their patron saint.
The hum ranges from 0.0037Hz to 0.0044Hz. Using the conventional MIDI frequency/pitch conversion formula p = 69 + (12 * log2(f/440)), the hum's pitch runs across almost exactly 3 semitones, a minor third, from just sharp of "B flat" to just sharp of "C sharp", 17 octaves above Middle C.
Four semitones is the range covered by a guitarist's fingers on a fretboard. The minor third is the most popular guitarist's composition interval.
Meanwhile, the Perseus Black Hole hums along a B flat. A bassline 57 octaves below Middle C, 74 octaves below the Earth's treble melody.
--
make install -not war
10 millihertz sounds more like a throb than a hum to me, perhaps even a chug.
Yes, but on a geological timescale, it's a hideous high-pitched whine.
If it's for-profit but free, you're not the customer -- you're the product (e.g., the Slashdot Beta's "audience").
Maybe this will explain some of the many mysterious hum phenomena.
"I don't know half of you half as well as I should like, and I like less than half of you half as well as you deserve."
It's the Ents!
I am at a loss as to why this matters. Does it affect anything?
On Slashdot, Red October hunts you!
Someone have a link to an audio file of this sound? (Sped up to a human-audible rate, of course.)
I do you one better. A tactile reproduction of the sound (sped up to a sensible rate)...
You'll need a fork and access to a power socket... In North America and Japan, this will allow you to feel the hum with a 6,000x speedup. In the UK, I think the speedup factor will be approximately 5,000x.
Enjoy!
Maybe it's an ommminous hummmm?
One line blog. I hear that they're called Twitters now.
A key breakthough was figuring out how to locate continuous signals. For normal earthquakes you have a sharp beginning. Using four or more seismographs you can invert for x,y,z and t0 (called triangulation).
For continuous signals you can find source by cross-corelating long pieces of signal from multiple locations. I first saw this in ambient noise submarine location, but the seismologists have now adopted it for analyzing some kinds of difficult signals like hum.
Me thinks it's all the rave dancing going on in Zion. Tell the damn Wachowski brothers to turn down the music!
Holy shit!
E to Bb! That's a TRITONE! THE SONG OF THE DEVIL!
Auuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuu!
THEY'RE HEARING HELL!
Do daemons dream of electric sleep()?
900 Hydrogen Bombs exploding at the same time 90 million years ago would obviously have devastating effects. E=mc^2, and PV=nkT/N so if 3000 x 10^10 J of energy were released, 5*60a = a3.66*10^23 *kt/2.718128 and would therefore explain the hum - residual energy from the blasts. It would of course decrease over time, proportionally, giving a e^x equation, which if you do the math, comes out to approximately 10 millihertz. My math is indisputable. May Jesus praise L Ron, and Almighty Science.
I'd like to teach the world to sing in perfect harmony
I'd like to buy the world a Coke and keep it company.
What?
you hum the.... umm... earth
:)
never mind
funny pics
aum shanti... , aum shanti... , aum shantihi...
sed -e 's/Chuck Norris/Rajnikant/g' joke > fact
http://en.wikipedia.org/wiki/Schumann_resonance
"What's the use of a good quotation if you can't change it?" - Doctor Who
Do people with mod points ever scroll down? I believe this is the third time this has been posted.
on mars the viking landers made a suprising discovery. Once every year the temperature and pressure conditions cause the entire atmosphere to shake globally. The seasonal cylce is not symmetric so it only happens once a year and it happens very close to the same day every year. This might seem weird but the martian atmosphere is about 100th as dense as ours so the sound waves can get pretty huge. I happen to known this because I helped discover it (using fortran 4!)
Some drink at the fountain of knowledge. Others just gargle.
I have my own theory. The earth has a molten iron core that rotates at a faster speed than the earth right?
I bet it's from that, not the friggen ocean. maybe the oscillations from the molten core resonate through the
ocean, but I'm willing to bet it's from the earth's molten core.
we know wind causes waves, and heating and cooling in the ocean cause currents, but even though waves can cause some noise, if you can hear this hum at the same level of audibility in the center on north america or russia, if that's the case, wouldnt that suggest that maybe it's something else?
hrmm I dunno, maybe like the plates themselves moving? the earth's inner works moving, or possibly the gravitational stresses brought on by the sun and the moon? (kinda like a creaking ship)
My point is, there are other factors here that could explain it too, though maybe they're at even lower frequencies.
however, if they can measure it at different sites and the "volume" of the hum decreases slightly as you get away from the ocean, then they're right.
...to 20 hz, considering our recent advances in water logic gates.
6 253.shtml
http://hardware.slashdot.org/hardware/07/02/16/04
Let's all say this together: "It's not a prediction if the measurement has already been done."
Working on your model until it aligns with obsrvations is how we got into the mess we're in with astrophysics (you know, the crappy Big Bang model constantly being changed to correlate with new observations). Why don't you try to get an actual prediction from your model, and then check with the real world? Maybe then you'd have something to talk about.
Ok, so having a model to explain this is good progress, because no good model existed before. Now go ahead and support the new model with evidence. What can it predict that hasn't been measured yet?
--Jaborandy
You can put tinfoil under your toes if you think it would help but they are talking about a seismographic hum... kinetic vibration, like sound. Maybe you should reconsider and put sound-absorbing foam insulation under them piggies.
;)
There is, however, another "hum" of the earth. An electromagnetic vibration that, amazingly enough, is very close to the frequency of a brain in meditation. Somehwere in th 7Hz range, if I recall. I don't feel like googling, that exercise is left to the reader. Maybe (in the days before massive man-made electromagnetic radiation), there was some merit for the holy people to have a tendancy to suggest we go barefoot, avoiding the electrically insulating tendency of footware. It has been found that the major acupuncture points correspond to variations in electrical impedance on the skin. Isn't that amazing? Well if you think about it, when you turn off an older T.V., you can "feel" the static that remains on the picture tube. I was fascinated by this as a kid. Now suppose in ancient times, sesnsitive people could "feel" the electric fields around our bodies... before the days of electronics and worldwide radio-wave (electromagnetic) transmissions swathed the globe. Could be.....
Things that make you go Hummmmmm....
Namaste
I'm just putting finishing touches on a computer simulation that clearly shows that the hum is caused by gasses produced by humans. Moreover, my simulation shows the hum literally ripping the planet in half in 50 years. I'd like to know where these other alleged researchers are getting their funding.
\documentclass[12pt]{article}
\usepackage{amsmath}
\begin{document}
One can measure the resonance of any object by dividing propagation speed by the object length. It's called the fundamental frequency.
\begin{align}
\text{Frequency} &= k * \frac{\text{speed}}{\text{length}} \\
\text{where,} k &= 1/2 \text{\ or\ } 1/4\text{, depending on the material.}
\intertext{Thus we can measure the frequency of the crust's natural resonance by dividing speed by wavelength.}
\text{Frequency} &= \frac{\text{Propogation speed of aftershocks through crust}}{\text{length of crust in direction of travel}} \\
&= \text{recipe to turn Earth into Quake 3 Arena.}
\end{align}
\end{document}
\bye
If this hum is caused by waves on the ocean floor, would a tsaumi change the pitch of the the hum and wouldn't that be detectable immediately.