Here is some info on a problem of electrophonic sounds, i.e. sounds simultaneous with a bright bolide passage.

My letter published in the November, 1998 issue of METEORITE! magazine, and the follow-up debates with C. Keay in the February 1999 issue;
My letter published in the Feb.3, 2001 issue of NEW SCIENTIST magazine;
My abstract for METEOROIDS 2001 conference;
Interesting account on probable electrophonic sound associated with a missile launch;
This fabulous World...;
Electrophonic sounds have been confirmed?!;
Sounds associated with Aurora have been recorded!
A brief comment regarding reviving of a light-heating idea.

ELECTROPHONIC SOUNDS

Sir,

I would like to comment Colin Keay's theory on electrophonic sounds (Meteorite!, August '98). At first, Keay's idea means that a bolide producing electrophonic sounds is to generate in its wake VLF radiation with the power at least about 10^12 W (Wang, D.Y., et al. J. Roy. Astron. Soc. Can. v.78, no.4, p.145 (1984)). As far as I know, no present theory either experiments with turbulent ionized wakes or predicts such superpowerful VLF radiation. Anyway, if it is realized somehow, it leads to spectacular effects, for example, to enormous Joule heating of the wake (due to extremely large electric currents) transforming the wake into object as bright (seen from the ground) as at least the Sun (see: Ol'khovatov, A.Yu. Geomagnetism and Aeronomy. English ed., v.33, no.2, p.264 (1993)). And, of course, this "super-radiation" would produce remarkable global effects - but none of them are known.

Moreover, the "electrophonic" bolides look like "ordinary" bolides - no signs of superpowerful electric currents in their wake (for example, see published in the Keay article the photo of the Peekskill fireball).

By the way, in many electrophonic events the power of aerobraking, i.e. the power deposited by a meteoroid into the atmosphere, which is to be the energy source of the proposed VLF radiation was much less that the power of the latter.

For example, on p.108 of December 1993 Sky & Telescope there is a photo of a "hissing" fireball of April 15, 1993, which became visible at a height of about 98 km and disappeared at 75 km after a flash with magnitude -9.5. Its looked like an "ordinary" bolide - no hints on the "superpowerful radiation" from it (I don't even touch here that it was too high for the existence of a "turbulent wake").

But the best example is the Space Shuttle re-entry, accompanied with electrophonic sounds. At that time the Shuttle was about 60-70 km high with a speed about 5-6 km/s (seen from the ground as an object with magnitude -1 to -2). Its aerobraking power was about 10^10 W. Moreover in its photo fortunately taken about the same time (see Aviation Week & Space Technology v.122, no. 3, p.85 (1985)) again there is no evidence of the "super-radiation".

I'd like also to add that, of course, some weak plasma instabilities in the wake under the action of ionospheric factors etc. can take place, anyway they are negligible compared with the "super-radiation".

Electrophonic phenomena have been observed in cases when it is known reliably that intense VLF radiation from the fireball wake did not occur. And I could add that if it takes place during the Shuttle re-entry, it would produce a devastating effect on its avionics and possibly even the crew and its fuselage!

By the way, Keay's remark that "the reports [on the Space Shuttle electrophonic sounds] ceased", also hints that the physical agent of the sounds was not produced by the Space Shuttle wakes, but more probably just was triggered by the flights in certain geophysical circumstances (see for details: Ol'khovatov A.Yu. Izvestiya [Russ. Acad. Sci.], Physics of the Solid Earth. English edition, v.29, no. 12, p.1043 (1993) and Priroda, no. 5, p.68 (1995) (in Russian)).

Andrei Ol'khovatov
Moscow, Russia

Electrophonic Sounds Debate

A. Ol'Khovatov (Letters, Meteorite!, November '98) asserts that bolides must generate "superpowerful radiation" for electrophonic sounds to be heard by witnesses on the ground. This is not a requirement of my theory for the production of electrophonic sounds from large bolides. Ol'Khovatov bases his claim of terawatt source power on figures published by Wang, et al.. (JRASC, 78, 4, 145-150, 1984) on the basis of electric field strengths of 160 V/m measured in my laboratory tests of direct human sensitivity without transduction by external artifacts (JRASC, 74, 5, 253-260, 1980). These fields happen to be in complete accord with earlier work by Ivanov and Medvedev (Geomag. and Aeronomy, 5, 216-219, 1965) who showed that comparable induced field variations could result from some bolides in appropriate trajectories when the Earth's geoelectric field is higher than usual. On the question of power levels, however, I consider as much more realistic Vitaly Bronsten's calculation (Solar Sys. Res., 17, 70-4, 1983) of megawatt source power based on my theory for the generation of the kilohertz radio emissions which give rise to observers hearing sustained electrophonic sounds.
On the question of energy requirements, it may be worth noting that in the early days of radio broadcasting, stations with a radiating power of only a kilowatt at distances of hundreds of kilometers could be received by unpowered crystal sets! Given an appropriate transducer the human ear is able to detect extremely low levels of power under quiet conditions.
Returning to the problem of electrophonic sounds from bolides, it is becoming apparent that there are many mechanisms by which ELF/VLF energy may be transmitted instantly to an observer, depending on the situation. Electromagnetic energy may be produced by explosive disruptions of a bolide (similar to the transient EM pulses from a nuclear air-blast), or by my mechanism (Science, 210, 11-15, 1980). Also there are purely electrostatic mechanisms such as that of Ivanov and Medvedev or simply the action of a zenithal meteor entering on a steep trajectory to produce a conductive path below the ionosphere which creates a strong transient in the geoelectric field at the surface of the Earth. This latter effect could explain the recent aural observations of Leonid fireballs by K Matsuura in Japan (private communication).
Clearly, much further study is needed to clarify outstanding problems of geophysical electrophonics.

Colin Keay
Physics Dept.
University of Newcastle
NSW, Australia

Ol'Khovatov replies...

In response to my criticism of C. Keay's theory about the origin of the electrophonic sounds, C. Keay states that just a megawatt power source of VLF/ELF radiation from a bolide's wake is enough to produce electrophonic sounds. But I can't accept his arguments.
The terawatt power source estimation is based on applying well-known formulas of electromagnetic radiation to Keay's idea. So to go down from "terawatts" to the "megawatts", C. Keay must find a mistake in Wang D. et al.'s calculations or change something in his theory. These are not done.
V. Bronsten was just trying to calculate the magnetic energy that could be stored in a bolide's wake according to the Keay theory and he got the energy relaxation rate estimation of "gigawatts". Then he speculated that about 0.001 of the energy could be transformed into radio waves. In other words, if his result is correct, it just imposes an upper limit on the power of the hypothesized radio waves - on the order of megawatts. As we just saw, it is a million times less than needed to produce the required 160 V/m electric field strength on the ground.
By the way, if the Keay "megawatt" estimation (which completely contradicts his 160 V/m value) is correct, that means that residents dozens of miles away from VLF/ELF radio stations (many of them have about such power) must hear the electrophonic sounds around the clock! And what about the radio station's personnel?
In my previous Letter, I also have mentioned several other evidences against the Keay idea. Even the shift from "terawatts" to "megawatts" is not able to avoid the majority of them. For example, even "megawatt" power can produce remarkable effects on Space Shuttle avionics. And, as I have written, the electrophonic sounds were heard when a rather weak bolide was too high for the existence of a turbulent wake. I hope that C. Keay will consider these aspects too, if he insists on his theory.

Andrei Ol'khovatov,
Moscow, Russia

In reply...

Ol'Khovatov still does not realize that detection of electrophonic sounds from fireballs relies on the presence close to the observer of a suitable transducer of adequate efficiency (hence my crystal set analogy). That is why observations of such sounds are rare and quite capricious. Time will tell who is correct. Right now an explanation for the phenomenon better than mine has yet to emerge. My explanation has thus far met most criticisms except those based on misinterpreted data."

Colin Keay

Editor's note: 1 megawatt = 1 million (10^6) watts, 1 gigawatt = 1 billion (10^9) watts, 1 terawatt = 1 trillion watts (10^12) watts. Further research involving the Space Shuttle to resolve this matter is being planned. Stay tuned.

SIZZLING SKIES

I read with interest Harriet Williams's article on various theories for the "electrophonic" sounds heard while watching auroras or meteors ( 6 January, p 14), the most serious problem with the theories is that the power of very low frequency (VLF) radio waves created by meteors is negligible compared with that needed to create audible sounds.

For example, lab experiments have shown that the sounds are inaudible when the power of the VLF waves drops below 160 volts per metre. This means that a meteor producing electrophonic sounds must, according to D. Y. Wang, generate at least 10^12 watts of VLF radiation (The Journal of the Royal Astronomical Society of Canada, vol 78, p 145). As far as I know, no current theory or experiments with turbulent ionised wakes predict such super-powerful VLF emissions.

If meteors could create this power, it would lead to spectacular effects: the enormous heating of the wake caused by extremely large electric currents would transform it into an object as bright as the Sun (Geomagnetism and Aeronomy, vol 33, p 264). So the nature of electrophonic sounds remains an enigma.

Andrei Ol'khovatov
Radio Instrument Industry Research Institute, Moscow

ON ELECTROPHONIC PHENOMENA Ol'khovatov A.Yu. Radio Instrument Industry Research Institute Moscow, Russia

During last years an idea that electrophonic sounds are caused by VLF electromagnetic radiation from a bolide's wake is promoted again. The source of the radiation is considered to be "magnetic spagetti relaxation" in a bolide's wake.
The most serious problem with the theory is that level of detected VLF disturbances, accompanied a bolide is negligibly small, comparing with needed for hearing VLF radiation. For example, C. Keay experiments revealed lower limit of hearing in order of 160 V/m. It means that a bolide producing electrophonic sounds is to generate in its wake VLF radiation with the power at least in order of 10^12 W. Nor present theory neither experiments with turbulent ionized wakes˙ predicts such superpowerful VLF radiation. Anyway, if it is realized somehow, it would lead to spectacular effects, for example, to enormous Joule heating of the wake (due to extremely large electric currents) transforming the wake into object as bright (seen from the ground) as at least the Sun. And, of course, this "super-radiation" would produce remarkable global effects - but none of them are known.
The presence of "transducers" near an observer can't help the situation, as the needed level to hear their vibrations are even in order of magnitude larger, and anyway, it can't be lowered down many orders of magnitude.
A solid confirmation that these estimations are correct is the fact that otherwise people would hear numerours VLF transmitters hundreds miles away! Also there were reports of electrophonic sounds during several Space Shuttle re-entries. The the hypothetical "super-radiation" (if exists) would produce a very remarkable (devastating) effect on the spaceplane.
Also, in many electrophonic events the power of aerobraking, i.e.the power deposited by a meteoroid into the atmosphere, which is to be the energy source of the proposed VLF super-radiation was much less that the power of the latter.

"The sound I heard was a very soft rushing sound. There was no breeze at the time. Furthermore the sound was not like the wind blowing. I've compared it to the sound of a sparkler without any popping noises but softer. The level was barely audible.
I dismissed them figuring they were imagined because I expected there should be a sound. It wasn't until I read Pierre Martin's website that I learned what it was.
When I observed the object, now reported as a missile, I was releasing a fish I had caught. I was kneeling at the edge of a pond in South Carolina when my three year old daughter called my attention to it. The sun had set but the sky was not yet completely dark. The trail of the object was slightly illuminated by the remaining rays. There were some very high clouds to the east. I can't remember if the moon had risen. The time was approximately 9:15, Eastern Standard Time (21:15 EDT). The report I filed is posted on the AMS Website Fireball Log at˙ http://www.amsmeteors.org/fireball/fireball_log.html (Item 65-3)
It was a still, humid night. The temperature was pleasant not sweltering hot - perhaps low 80's. There is only one road nearby which crosses the pond on the dam. No traffic was on it. There was no one else about. The rest of the family was in the house.
The house is on a large lot and the neighbors are not close. The pond is probably a couple of acres in size. The closest structure was a 12 foot by 12 foot wooden dock, perhaps 10 ft (about 3 meters) away from me. It was in front of me as I observed the object. To my left was a pump for the lawn irrigation - perhaps 4 meters away. On my right, a little farther away was a metal fishing boat about 3 meters in length. Pipes run under the ground for the spinklers. I don't know if the pipe is metal or plastic. The topography of our area is generally flat. In the immediate area it slopes gently down from the house to the pond.
I did not immediately hear the sounds when I saw the object but they followed occuring to my best recollection over the last half of the flight and ending perhaps shortly before it became obvious that the object had ceased making a smoke trail. By the time I heard the sound I was standing holding my daughter's hand. I may have been holding her.
Needless to say, it had my full attention and was an awesome sight. I do not wear glasses. My hair is cut short, long enough to just cover my ears. I was not wearing a hat. The sounds were extremely subtle, soft enough to make me doubt that I had heard them as nothing nearby could supply so soft a sound. A psychologist would find this following conclusion suspect since I have read a few theories about the source of electrophonic sounds the week following the event. That said, it was as if the source of the sound was unidentifiable but nearby. It was unlike hearing regular sounds. I remember trying to determine if I had really heard the sounds but since I didn't have an immediate source, I dismissed them as a function of my imagination. However, when I think on it, the rushing sound I heard, is not the one I think I would have fabricated. I think that a sound of a louder more conventional type is what the imagination would have supplied."

ELECTROPHONIC METEORS AND METEOR-ATMOSPHERE COUPLING

>From Slaven Garaj 

Dear Benny and colleagues,

I would like to draw your attention to a recent article from our group,
entitled: "Instrumental recording of electrophonic sounds from Leonid
fireballs", by G. Zgrablic et al. The article considers the phenomenon of
the electrophonic meteors and it will appear in the Journal of
Geophysical Research.

The electrophonic sounds, which are heard simultaneously with an appearance
of a bright meteor, are a longstanding astronomic mystery. This is the
contra-intuitive phenomenon: normal sounds from a meteor should lag behind
the meteor couple of minutes, due to relatively small velocity of sounds. A
full evaluation of the electrophonic phenomenon was undermined by the lack
of instrumental recordings - only witness reports existed.

In the article, we present the first instrumental recording of the
electrophonic sounds detected during the ILWC expedition to Mongolia. We
demonstrate that physical characteristics of electrophones from Leonid
meteors cannot be explained satisfactory in the framework of the
existing theories. In addition, it is suggested that the coupling of meteors
to atmospheric charge dynamics and ionosphere is much stronger than
previously expected. This can have more general implications, beyond the
electrophonic phenomenon.

Preprint of the article and additional information, pictures and videos can
be accessed at the project's web page: http://fizika.org/ilwcro/results/

In addition, I would like to direct you to the project "Global Electrophonic
Fireball Survey", coordinated by D. Vinkovic from Univ. of Kentucky. The aim
of the project is to collect witness reports of the electrophonic sounds. If
you experienced electrophonic phenomena, please fill up the on-line form and
make an important contribution to the understanding of this effect. Web
address: http://gefs.ccs.uky.edu/

Greetings,

Slaven Garaj
ILWC coordinator

Institute of Nuclear Engineering (IGA)
Department of Physics
Swiss Federal Institute of Technology Lausanne (EPFL)
CH-1015 Lausanne
Tel.: +41 (21) 693 4337
Fax: +41 (21) 693 4461
e-mail: slaven.garaj@epfl.ch
homepage: http://nanotubes.epfl.ch/garaj/

ELECTROPHONIC METEORS AND METEOR-ATMOSPHERE COUPLING

>From Andrei Ol'khovatov 

Dear Benny and All,

In CCNet 13/2002 - 23 January 2002 there was a post by Slaven Garaj
"ELECTROPHONIC METEORS AND METEOR-ATMOSPHERE COUPLING". I enjoyed reading
the post and the refered article in the Journal of Geophysical Research. I
would like to congratulate authors of the article. It is the first known
scientific confirmation of electrophonic sounds reality.

The article also confirms what I wrote for more than a decade (see
www.geocities.com/olkhov/electro1.htm and ref. in it), i.e. that the

theory of "magnetic spagetti" relaxation in a wake of a meteor can't explain
electrophonic sounds. Also it is interesting to find out that
authors of the article come to an idea, similar to the one, which I
published first more than a decade ago, i.e. that a meteor is probably just
a trigger of geophysical processes producing electrophonic sounds in
specific geophysical conditions. I can just hope that in their next article
they will mention this...

Best wishes,

Andrei Ol'khovatov

Russia Moscow

www.aalto.fi/en/current//news/view/2012-07-09/

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