Help me debunk my own "unidentified" audio experience

Anomalous sound propagation could be involved too.

I tried to look for references, but only found rather old (and not much informative) papers. From what I could see, however, conditions may arise where a sound is heard near its source, not heard further from it, then heard again even further, possibly with multiple reflections.

This is the abstract of a 1956 paper (the paper itself is behind a paywall, bold is mine):
External Quote:


https://pubs.aip.org/asa/jasa/artic...-the-Lower-Atmosphere?redirectedFrom=fulltext

This is from 1911...

External Quote:
https://www.jstage.jst.go.jp/article/ptmps1907/6/9/6_9_132/_pdf/-char/en

That's interesting - never heard of those before.
Given low levels of observation on the upper atmosphere and the infrequency of some events (sprites, ELVES etc.) - rare atmospheric conditions are a good possibility for any unexplained energetic outputs IMO.

how sure are you about the 10:20 time frame? its been 10 years and in OP you didnt know the week or even the year exactly but you gave an exact time. is it possible your memory is polluted by reports at that time of people saying "around 10-10:30?

mostly because that flickr fireworks at 7pm, i linked above, would likely be hearable from your location. certainly you werent hearing the Banstead engagement party.
And because i heard strange noises several times..and eventually drove my car out to find it as it was bizarre.. turned out it was the High School band playing (probably during football games). The high school was further away then you'd think you would hear a band percussion. But even though i drove out maybe 5 years ago to locate source, i could only tell you "it was dark" i literally have no idea if it was 10ish or 7ish etc. My memory of the time is completely gone as "time" wasnt my focus then.

Heh- fair comment about not even knowing the week/year.
I cant be 100% sure it was 10:20 exactly- but I am 100% sure it was between 10:00 and 10:30 as I have a set routine on work nights.
 
I just remembered Brian Dunning at www.skeptoid.com has a couple articles on 'noises from the sky': Sky Trumpets and Can you hear the hum? The most pertinent is the first one, this is an excerpt:

External Quote:

THERE HAVE BEEN SEVERAL REPORTS OF VERY STRANGE SOUNDS FROM THE WOODVILLE AREA SINCE ABOUT 645 PM EST. THE NATIONAL WEATHER SERVICE BELIEVES THIS PHENOMENON IS BEING CAUSED BY THUNDER FROM DISTANT LIGHTNING STROKES… BOUNCING OFF A VERY STABLE LAYER ABOVE THE GROUND. THIS IS CALLED DUCTING… AND CAN ALLOW SOUND TO TRAVEL UNUSUALLY LONG DISTANCES. THIS SOUND HAS BEEN MISTAKENLY ATTRIBUTED TO POSSIBLE TORNADOES… BUT WE AT THE NATIONAL WEATHER SERVICE WANT TO BE VERY CLEAR THAT THERE ARE NO TORNADOES… AND NONE ARE EXPECTED.
Ducting, they say? Yes, that's a thing, but it rarely applies to noise, almost always to radio signals. Tropospheric ducting is when a signal refracts back down toward the ground from a temperature inversion layer. This is very familiar to amateur radio enthusiasts. You can actually see them sometimes; since light is also electromagnetic radiation, ducting is what causes certain superior mirages like those we often see on the horizon looking out to sea.


The reason it's so rare for atmospheric ducting to do anything unusual with sound is that sound doesn't travel very far; rarely far enough to be affected. It has to be a really, really loud sound; and thunder is one type of sound that's loud enough. If the conditions are just right, as it seems they may have been on that day in 2011 in that part of Florida, very loud noises can propagate unusually far, complete with reverberation.
(I'm not saying what you heard were distant thunders, that's just an example, the articles itself stresses there are many possible sources for the original noise)

Wikipedia has an article on the same phenomenon: Skyquake, with a list of many possible explanations:

External Quote:

Their origin has not been positively identified. They have been explained as:


  • Coronal mass ejection CMEs often generate shock waves similar to what happens when an aircraft flies at a speed higher than the speed of sound in Earth's atmosphere (sonic boom). The solar wind's equivalent of a sonic boom can accelerate protons up to millions of miles per minute—as much as 40 percent of the speed of light.[citation needed]​
  • Meteors entering the atmosphere causing sonic booms.[7]
  • Gas:
    • Gas escaping from vents in the Earth's surface.[citation needed]​
    • With lakes, bio gas from decaying vegetation trapped beneath the lake bottoms suddenly bursting forth. This is plausible, since Cayuga Lake and Seneca Lake are large and deep lakes.[citation needed]​
    • Explosive release of less volatile gases generated as limestone decays in underwater caves.[citation needed]​
  • Military aircraft creating sonic booms (though this origin cannot explain occurrences before supersonic flight started).
  • Shallow earthquakes can generate sound waves with little ground vibration. The "booming" sound is heard only in a localized area around the epicenter.[7][8]
  • Underwater caves collapsing, and the air rapidly rising to the surface.
  • Possible resonance from solar and/or earth magnetic activity inducing sounds.[9]
  • Volcanic eruptions
  • Weather
  • Earthquake
  • Avalanches, either natural or human-made for avalanche control.
  • Atmospheric ducting where distant thunder or other sounds are propagated across long distances due to travel through distinct atmospheric layers.[10]

Meteors, atmospheric ducting of a distant sound and sonic booms (with or without ducting) look the most probable to me (at least, gas escape, volcanoes, avalanches and the like should be rather easy to rule out).
 
Meteors, atmospheric ducting of a distant sound and sonic booms (with or without ducting) look the most probable to me (at least, gas escape, volcanoes, avalanches and the like should be rather easy to rule out).
The list left out deliberate blasting - for quarrying, perhaps, or for seismic mapping of underground features.
 
And maybe an EDM music festival featuring a DJ with a really strange sense of rhythm.
I live not too far from an interstate highway that is having a lane added. I am used to the distant hum of traffic and it doesn't bother me. But as for the road work, I don't know exactly where the heavy equipment is at any given moment, but I'm definitely aware that they all start work promptly at 7:30.
 
All fair comments I suppose.
If you didn't hear it first hand- the audio doesn't do it justice so I can understand people saying fireworks.

The original post was borne out of frustration.

The fact that another independent witness who is also a sky watcher and Dr. of Astronomy (Matt Burleigh) thought it was extraordinary (i.e not caused by sonic booms/roadworks etc) and felt the best explanation might be upper atmospheric interactions makes me feel somewhat vindicated.

Noises like that - heard by witnesses separated by such distance are hard to explain so I still share Dr Burleighs sentiments of "I am now wondering if this event is actually quite rare and exciting…." .

Next step is to plot those alleged sightings to alleged locations and if anyone wants to do some audio isolation - please post your results here.
 
All fair comments I suppose.
If you didn't hear it first hand- the audio doesn't do it justice so I can understand people saying fireworks.

The original post was borne out of frustration.

The fact that another independent witness who is also a sky watcher and Dr. of Astronomy (Matt Burleigh) thought it was extraordinary (i.e not caused by sonic booms/roadworks etc) and felt the best explanation might be upper atmospheric interactions makes me feel somewhat vindicated.

Noises like that - heard by witnesses separated by such distance are hard to explain so I still share Dr Burleighs sentiments of "I am now wondering if this event is actually quite rare and exciting…." .

Next step is to plot those alleged sightings to alleged locations and if anyone wants to do some audio isolation - please post your results here.
The sound channel in the ocean (which is exploited by the SOFAR system and also by whales) is known to transmit low frequency sounds better than higher frequency sounds. So the sound channel acts in part as an audio filter. Ann K pointed out earlier in the thread that a temperature inversion can create something like a smaller scale sound channel, using the same lensing effect seen in the SOFAR system. Interestingly, the use of the sound channel in the air was also used in Project Mogul to spy on the Russians. An accident with the project is the official reason for the Roswell incident.

If Ann K is right, you would have a lot of attenuation of higher frequencies, and some attenuation of the middle frequencies.

Perhaps if you were to take the audio of fireworks and pull out the upper frequencies, and lower the mid-frequencies you might find it sounds more like what you actually heard.

By the way the best explanation of the SOFAR system, the sound channel. Project Mogul, the lensing effect in fluids and the Roswell Incident that I have ever seen is below.


Source: https://www.youtube.com/watch?v=Vlqq7cc4VrI&list=PLDGjfpzzwYX4NwbQThgezgAM76JrLU5wK&index=12
 
maybe he's done further research, have you tried contacting him?

Yes.
Sent him a link to this thread and will follow up.

The fact his first port of call was a meteor specialist (bearing in mind Matt is an academic involved in discovery science) speaks volumes.

Suspect the only action that will move things forward is contacting all witnesses and doing a map cross referencing times as there is no other observational data (unless we have a Dr Kent Clark from Contact amongst us).
 
If Ann K is right, you would have a lot of attenuation of higher frequencies, and some attenuation of the middle frequencies.
Anecdotally, I live about two and a half miles from the local high school, and when the band plays I hear only the drumbeats. I have to get much closer before I can discern any of the higher musical tones at all. That seems to be true regardless of the atmospheric conditions.
 
Anecdotally, I live about two and a half miles from the local high school, and when the band plays I hear only the drumbeats. I have to get much closer before I can discern any of the higher musical tones at all. That seems to be true regardless of the atmospheric conditions.
If I've remembered correctly, higher frequencies rely on the air molecules changing direction, an energy losing action, more abruptly and also more often, so it's not even linear, it's closer to a square relationship between frequency and attenuation.
External Quote:
In acoustics, Stokes's law of sound attenuation is a formula for the attenuation of sound in a Newtonian fluid, such as water or air, due to the fluid's viscosity. It states that the amplitude of a plane wave decreases exponentially with distance traveled, at a rate α given by
α = 2 η ω^2 / (3 ρ V^3)
where η is the dynamic viscosity coefficient of the fluid, ω is the sound's angular frequency, ρ is the fluid density, and V is the speed of sound in the medium.
-- https://en.wikipedia.org/wiki/Stokes's_law_of_sound_attenuation
 
If I've remembered correctly, higher frequencies rely on the air molecules changing direction, an energy losing action, more abruptly and also more often, so it's not even linear, it's closer to a square relationship between frequency and attenuation.
External Quote:
In acoustics, Stokes's law of sound attenuation is a formula for the attenuation of sound in a Newtonian fluid, such as water or air, due to the fluid's viscosity. It states that the amplitude of a plane wave decreases exponentially with distance traveled, at a rate α given by
α = 2 η ω^2 / (3 ρ V^3)
where η is the dynamic viscosity coefficient of the fluid, ω is the sound's angular frequency, ρ is the fluid density, and V is the speed of sound in the medium.
-- https://en.wikipedia.org/wiki/Stokes's_law_of_sound_attenuation
Thanks for clarifying that. I wasn't sure whether or not the loss off higher frequencies was a function of the sound channel preferentially bending the higher frequencies such that they were flung out of the sound channel or whether or not the loss of higher frequency was a simple biproduct of the longer distance travelled (or both). So it appears to be either all or mostly down to higher frequencies not being able to make a long journey.
 
Thanks for clarifying that. I wasn't sure whether or not the loss off higher frequencies was a function of the sound channel preferentially bending the higher frequencies such that they were flung out of the sound channel or whether or not the loss of higher frequency was a simple biproduct of the longer distance travelled (or both). So it appears to be either all or mostly down to higher frequencies not being able to make a long journey.

So - presumably any accurate frequency analysis of distant sounds (recorded in atmosphere) will only be possible if you know rough distance between observer and emitter?
Throw in the possibility of moving sources, multiples or the effects of frequencies having to traverse differing medium densities- I'm left thinking identification via acoustic finger printing would be almost impossible.

If I accept fireworks "in atmosphere" can sound different- there's still the issue of why at least 3 people in the UK (Me, Dr Burleigh and @virtualastro) thought they heard this fantastically extravagant "none firework sounding display" at around the same time, whilst being separated by distances of up to 140 miles.

The anecdotal /non verifiable twitter evidence of people hearing it in Scotland/the states/ME isn't required as the above still requires a none mundane explanation IMO.
 
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So - presumably any accurate frequency analysis of distant sounds (recorded in atmosphere) will only be possible if you know rough distance between observer and emitter?
It may not be as complicated as you think.

You could try the following:-
- Pick a few equally spaced distances between say 1-5 kilometres or thereabouts (eg 1.5 km, 2.0 km, 2.5 km... etc).
- For each distance, use Phil's equation above to calculate the attenuation between say 20-10,000 Hz (again, just pick some of the intervals that match your equalizer settings).
- Download some audio of fireworks.
- Pick the distance in the middle. Use the graph you made to configure the equaliser settings and play. If it sounds the same as what you heard, great! If not, move either side of the middle and try again.

An easier way would be to just drop everything but the bass. I don't know what values you should plug in for the dynamic viscosity coefficient or the fluid density (perhaps FatPhil would know), but I can see that as frequency increases, the loss of volume increases exponentially with frequency. Ann K had indicated at a fairly short distance she could not hear the instruments of the band, only the drums indicating that even over the minimum distance for this type of weather effect, there were only bass frequencies present.
 
Wikipedia has an article on the same phenomenon: Skyquake

Must admit I didn't really pay enough attention to Mauro's post at the time (Soz Mauro! ;)) but it might be worth considering one or two of the explanations proposed for "skyquakes", very loud bangs apparently from the sky and without an obvious cause, sometimes heard over a large area.

There's now a thread here about skyquakes,
https://www.metabunk.org/threads/skyquakes.13681/#post-324585

I posted this:
The "Bell Island Boom" of 1978 in Newfoundland, Canada might be an example of a skyquake. Possibly caused by an unobserved superbolt, an unusually powerful lightning strike. Wikipedia article "Bell Island (Newfoundland and Labrador)":
External Quote:

Bell Island Boom
On Sunday, April 2, 1978, a huge bang was heard at Bell Island just before noon. The bang was so loud that people reported hearing it as far as 100 km away. The blast sent a shock wave that shook buildings on the island and killed some animals. The energy release was so powerful that the Vela satellites (which the US government used to detect nuclear tests by other powers) noticed the phenomenon, now known as the Bell Island Boom.
There were multiple reports of damaged electrical wiring and destroyed electrical appliances. The epicentre was around the Bickford family farm in the hamlet of Bickfordville, near Lance Cove. They claimed to have seen a gigantic bluish flame and both their television set and fuse box had exploded. The chicken coop was completely destroyed and all the chickens had died. Neighbours soon discovered three large pits in the snow behind the farm, which were considered "epicentre". The son who was cycling nearby at that time also stated that he saw two luminous spheres flying by.
All sorts of hypotheses about the cause quickly emerged, from rational explanation attempts to conspiracy theories. In general, based on the evidence, it is assumed that it was a superbolt, a rare and very powerful type of lightning occurring only about once per two million lightning strikes or so, normally high in the atmosphere or above the ocean. This was also the conclusion of two scientists at the Los Alamos Scientific Laboratory who detected "superbolts" using data from the Vela satellites and therefore conducted an on-site investigation shortly after the incident.
https://en.wikipedia.org/wiki/Bell_Island_(Newfoundland_and_Labrador)#Bell_Island_Boom.
 
Must admit I didn't really pay enough attention to Mauro's post at the time (Soz Mauro! ;)) but it might be worth considering one or two of the explanations proposed for "skyquakes", very loud bangs apparently from the sky and without an obvious cause, sometimes heard over a large area.

Me too....apologies Mauro
I suspect it probably was a rare atmospheric event however never heard anything similar in terms of repeated, regular emissions.

Identifying the cause is likely hopeless if correct as we've basically got this very large open system (the atmosphere) that receives none constant, none uniform energetic interactions from both space and Earth.

Throw in exotic space borne interactions that occur rarely at altitudes few humans ever go or the possibility of humans conducting high energy output activities and we shouldn't really be surprised by any unexplained atmospheric event (if we are being honest).
 
Not had chance to do much with this yet but as an update- couldn't help but notice how similar the recent Space X launch sounded (at points):


Never noticed the pulsing effect before and previous launch videos dont seem to capture it (if it is a routine occurrence).
 
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