Dental filling radio reception?

[Bob Masta]

Hi, everyone.

For years I've heard vague stories about people receiving radio
broadcasts through their dental work. The stories have all the
characteristics of a classic urban legend, and I'm pretty sure
that's exactly what they are. Although I have no doubt that
some people *think* they are hearing radio broadcasts, I
believe that if proper tests would have been conducted it
could have been shown that these were really mild auditory
hallucinations.

So my question here has to do with the pure physics of a
supposed dental radio receiver. The proponents usually
do some hand-waving about the possibility of a diode
forming in connection with a metallic filling or bridgework.
The possibility seems at least plausible (any thoughts on that?),
but they never seem to follow it any further. OK, so what is
this diode going to connect to? How is the signal going to
get transduced into sound? Etc, etc.

But the real show-stopper, I think, would be the fact that
the whole "radio" is inside the mouth, surrounded by
conductive tissue with no antenna protruding... a pretty
good Faraday cage, I reckon. (Or maybe the radio
only works when you stick out your toungue...!)

So the question is just how good of an RF shield
is conductive tissue at normal AM or FM frequencies?
Anyone have any data, or know how to compute it
if we come up with some estimates for tissue conductivity
and thickness?

Thanks!


Bob Masta
dqatechATdaqartaDOTcom

D A Q A R T A
Data AcQuisition And Real-Time Analysis
www.daqarta.com

 

[M.Daughtry]

You need to catch the re-run of Myth Busters where they tested this very
thing. IIRC (because I really wasn't paying a whole lot of attention) their
conclusion was that it was plausible but not very likely (someone chime in
if I'm wrong).

--
Best regards,
Mark Daughtry, SR
It takes "BALLS" to shoot a muzzleloader.

"Bob Masta" <NoSpam@daqarta.com> wrote in message
news:41dd48ed.2052188@news.itd.umich.edu...

Hi, everyone.

For years I've heard vague stories about people receiving radio
broadcasts through their dental work. The stories have all the
characteristics of a classic urban legend, and I'm pretty sure
that's exactly what they are. Although I have no doubt that
some people *think* they are hearing radio broadcasts, I
believe that if proper tests would have been conducted it
could have been shown that these were really mild auditory
hallucinations.

So my question here has to do with the pure physics of a
supposed dental radio receiver. The proponents usually
do some hand-waving about the possibility of a diode
forming in connection with a metallic filling or bridgework.
The possibility seems at least plausible (any thoughts on that?),
but they never seem to follow it any further. OK, so what is
this diode going to connect to? How is the signal going to
get transduced into sound? Etc, etc.

But the real show-stopper, I think, would be the fact that
the whole "radio" is inside the mouth, surrounded by
conductive tissue with no antenna protruding... a pretty
good Faraday cage, I reckon. (Or maybe the radio
only works when you stick out your toungue...!)

So the question is just how good of an RF shield
is conductive tissue at normal AM or FM frequencies?
Anyone have any data, or know how to compute it
if we come up with some estimates for tissue conductivity
and thickness?

Thanks!


Bob Masta
dqatechATdaqartaDOTcom

D A Q A R T A
Data AcQuisition And Real-Time Analysis
www.daqarta.com

 

[John Popelish]

Andrew Holme wrote:

John Popelish wrote:
"M.Daughtry" wrote:

You need to catch the re-run of Myth Busters where they tested this
very thing. IIRC (because I really wasn't paying a whole lot of
attention) their conclusion was that it was plausible but not very
likely (someone chime in if I'm wrong).

I didn't see the show, but the antenna efficiency for this sort of
thing is extremely low. You would have to sit beside the transmitting
antenna to have a chance of it happening.

Sit beside the transmitter, chewing on a mouth full of OA91 germanium
diodes.

Aluminum foil gum wrappers against amalgam filling might also rectify
a bit.

--
John Popelish

 

[Stranger in the dark]

"Don A. Gilmore" <eromlignodNOSPM@kc.rr.com> wrote in message
news:345i45F46iguqU1@individual.net...

"Stranger in the dark" <Onlytheshadowknows@darksecrets.com> wrote in
message
news:VhgDd.34689$NC6.23940@newsread1.mlpsca01.us.to.verio.net...
Ok, here's one for ya....

I was about 12 at the time. We had gone away for a couple hours - my
mother,
younger brother and myself. We merely went to the store to pick up a
couple
things, a total of 10 miles round trip. My Dad and I believe one other
person was at home. There was a hail storm came through that day and
lasted
about 15 minutes. The house had a basement, 1st floor and 2nd floor. The
first floor in the kitchen - the dome which hung from the kitchen ceiling
lamp had hail and water in it. There was NO leaks in the roof, no leaks
evident in the bedroom above the kitchen. No way we could think of, for
the
water/hail to have gotten in that dome. While I'm sure there must be some
reasonable explanation for it, it sure defied one and still does - at
least
to the writing of this. That was the first and last we noticed that sort
of
thing - in our time there.


Maybe Jesus put it there...or your little brother.

Nah, don't think so...... Little brother couldn't reach it and beside, he
was with us! Jesus - well, to each his own - but I don't think such a
person/entity would waste their time doing stupid tricks like that. Try
again.

The Shadow

 

[Don Bruder]

In article <VA.00000081.000f2457@btinternet.com>,
Joe McElvenney <ximac@btinternet.com> wrote:

Hi,

Then there's getting speech or music out of the gas stove.
That is a little more plausible as I seem to recall that a flame
can be used as an RF detector.

More interesting is using a flame as a speaker.

Yes, this one's actually for real, and *INCREDIBLY* effective. Once
things are set up and adjusted properly, it can be tweaked to produce
enough volume to practically blow you into the next county. I don't
claim full understanding of the workings, but I've seen it in action,
and I was *VERY* impressed, both with the quality and quantity of sound
output. A propane flame that looked to be about 10 inches tall from my
vantage point in the bleachers was WAY more than adequate for use as a
PA speaker at the county fairgrounds where the demonstration was done,
and was reported to be heard, clearly enough to be intelligble, more
than a mile away.

Of course, the heat that came as a by-product, and the clear space
required to prevent it from being a fire hazard, was something of a
downside. (The demo was set up in the infield of the harness-racing
track)

--
Don Bruder - dakidd@sonic.net - New Email policy in effect as of Feb. 21, 2004.
Short form: I'm trashing EVERY E-mail that doesn't contain a password in the
subject unless it comes from a "whitelisted" (pre-approved by me) address.
See <http://www.sonic.net/~dakidd/main/contact.html> for full details.

 

[Robert Monsen]

Bob Masta wrote:

Hi, everyone.

For years I've heard vague stories about people receiving radio
broadcasts through their dental work. The stories have all the
characteristics of a classic urban legend, and I'm pretty sure
that's exactly what they are. Although I have no doubt that
some people *think* they are hearing radio broadcasts, I
believe that if proper tests would have been conducted it
could have been shown that these were really mild auditory
hallucinations.

So my question here has to do with the pure physics of a
supposed dental radio receiver. The proponents usually
do some hand-waving about the possibility of a diode
forming in connection with a metallic filling or bridgework.
The possibility seems at least plausible (any thoughts on that?),
but they never seem to follow it any further. OK, so what is
this diode going to connect to? How is the signal going to
get transduced into sound? Etc, etc.

But the real show-stopper, I think, would be the fact that
the whole "radio" is inside the mouth, surrounded by
conductive tissue with no antenna protruding... a pretty
good Faraday cage, I reckon. (Or maybe the radio
only works when you stick out your toungue...!)

So the question is just how good of an RF shield
is conductive tissue at normal AM or FM frequencies?
Anyone have any data, or know how to compute it
if we come up with some estimates for tissue conductivity
and thickness?

Thanks!

Lucille Ball told a story on "The Dick Cavett Show" about picking up
morse on her fillings after a trip to the dentist. She claims that she
was driving by a big short wave transmitter. There is also a claim that
she captured a Japanese spy during WWII with it...

When I was a kid, I used to hear morse late at night. I had several
large fillings. My guess is that a neighbor had a big shortwave
transmitter, and used it at night. I don't know morse, so it may have
been an auditory hallucination, but it was repeated at least a few
times, and, well, it really sounded like morse. Very spooky.

One theory is that is amalgam in fillings creates a diode. The strong
wave rolling across it creates electrical impulses, which trick the
auditory system (which is about a cm away, through that conductive media
you were referring to) into believing there was sound. It probably only
works for big fillings on the uppers, far back in the mouth, and then
only with certain shapes and depth of filling, and formulas of amalgam.

--
Regards,
Robert Monsen

"Your Highness, I have no need of this hypothesis."
- Pierre Laplace (1749-1827), to Napoleon,
on why his works on celestial mechanics make no mention of God.

 

[Bob Masta]

On 6 Jan 2005 08:53:53 -0800, dave.harper@gmail.com wrote:

<snip>

However, I'd like to play devil's advocate and point out a few
things... first is that tissue does not make a good faraday cage. You
are a better conductor than rubber, but MUCH worse than copper. UHF
and VHF passes through you relatively easily.

Any idea where to get numbers to put on this? I'm especially
interested in AM frequencies, simply because AM broadcasts
can be easily detected, as in a crystal radio. But figures for
the other bands would certainly be of interest.

Secondly, do you want to assume that, if this legend is true, the
filling induces sound in the mouth? Electrical impulses transmitted
around your auditory nerve definately seem like sound to the beholder.
Maybe that's the mechanism...?

Electrical pulses transmitted directly to your auditory nerve, as in
an auditory prosthesis (cochlear implant) sound like buzzing. In
order to get any semblance of the original sound you need a
carefully orchestrated stimulation of multiple frequency regions.
This is a really difficult task, with a lot of good people working
hard on it. The problem is that the ear is not at all like a
radio or telephone. It's a parallel device, with all frequencies
analyzed while still acoustic, and transmitted as thousands
of discrete frequencies on individual auditory nerve fibers.
Each fiber's firing rate corresponds to the intensity of the
particular frequency of the corresponding sensory cell.
There is no place in the system where you can insert an
electrical audio signal and have it interpreted by the brain
as the original sound. (Unless perhaps your signal was
a buzzer!)

Lastly, who's to say the filling acts as an antenna, a diode, or a
battery? A filling in a saline solution, surrounded by nerves, bone,
and other tissue might act completely differently than it would
stand-alone.

Yes, my expectation is that if there is any diode junction at all,
it's between metal and an electrolyte.


Best regards,


Bob Masta
dqatechATdaqartaDOTcom

D A Q A R T A
Data AcQuisition And Real-Time Analysis
www.daqarta.com

 

Bob Masta wrote:

On 6 Jan 2005 08:53:53 -0800, dave.harper@gmail.com wrote:

snip

However, I'd like to play devil's advocate and point out a few
things... first is that tissue does not make a good faraday cage.
You
are a better conductor than rubber, but MUCH worse than copper. UHF
and VHF passes through you relatively easily.

Any idea where to get numbers to put on this? I'm especially
interested in AM frequencies, simply because AM broadcasts
can be easily detected, as in a crystal radio. But figures for
the other bands would certainly be of interest.

Not off the top of my head. Some mil-standards/specs might have that
information. The statement "the body is a good conductor" can be true
or false, depending on what you're using as reference. It's a great
conductor compared to rubber, concrete, etc. It's an extremely poor
conductor compared to copper, gold, even lead.

I'm guessing that microwaves and x-ray machines would be worthless if
meat was a good conductor.

Secondly, do you want to assume that, if this legend is true, the
filling induces sound in the mouth? Electrical impulses transmitted
around your auditory nerve definately seem like sound to the
beholder.
Maybe that's the mechanism...?

Electrical pulses transmitted directly to your auditory nerve, as in
an auditory prosthesis (cochlear implant) sound like buzzing.

That statement is incorrect. If cochlear implants only sounded like
buzzing, then people wouldn't have them implanted. I think you're
refering to the lower quality of the sound compared to natural hearing?
Perhaps this quote could help:

"The sounds heard through an implant are different from the normal
hearing sounds, and have been described as artificial or "robotlike."
This is because the implant's handful of electrodes cannot hope to
match the complexity of a person's 15,000 hair cells."

http://www.chclibrary.org/micromed/00043180.html

In
order to get any semblance of the original sound you need a
carefully orchestrated stimulation of multiple frequency regions.

Multiple frequencies you mean? Sound can be a single frequency or a
superposition of many.

This is a really difficult task, with a lot of good people working
hard on it. The problem is that the ear is not at all like a
radio or telephone. It's a parallel device, with all frequencies
analyzed while still acoustic, and transmitted as thousands
of discrete frequencies on individual auditory nerve fibers.
Each fiber's firing rate corresponds to the intensity of the
particular frequency of the corresponding sensory cell.

I don't believe that's a correct statement. If it was solely dependant
on frequency, then you couldn't tell the difference between a 50Hz
square wave, a 50Hz sine wave, or a 50Hz tuba note.

Just because everyday sound usually has many different origins
operating at different frequencies doesn't mean you can't hear a single
noise at a single frequency.

There is no place in the system where you can insert an
electrical audio signal and have it interpreted by the brain
as the original sound. (Unless perhaps your signal was
a buzzer!)

Isn't that the "goal" of a cochlear implant? To simulate real-world
noise in the auditory nerve? As stated above, just because the implant
can't mimic the the hairs in your ear perfectly doesn't mean it can't
be done. That's a current-day limitation, not a permanent one.

Dave

 

[Bob Masta]

On Sun, 16 Jan 2005 08:22:09 +0100, Dr Engelbert Buxbaum
<engelbert_buxbaum@hotmail.com> wrote:

Bob Masta wrote:

Hi, everyone.

For years I've heard vague stories about people receiving radio
broadcasts through their dental work. The stories have all the
characteristics of a classic urban legend, and I'm pretty sure
that's exactly what they are.

Hmm, I could imagine the amalgam to act as a crystal detector, like in
the early radios in the 1920's. But what would act as ear phone, and
what as resonance circuit?

As noted in other responses, a resonant circuit is not mandatory,
especially for strong local AM stations. I suspect anyone who has
ever built a simple crystal radio (diode or traditional) in an urban
area has noted that one strong local station seems to dominate the
whole band, regardless of where tuned.

Likewise, there are electromechanical transduction processes that
work on biological tissue. The ones I have experimented with work
at higher voltages (several volts RMS), but that was to produce a
sound that was audible in free air. (This was a signal generator
with a paper clip on the hot lead. If you brushed your fingertip
on the clip in *just* the right way, you could hear the oscillator
frequency. Don't recall how the ground was connected.)

And of course the best example of a bio-electro-mechnical
transducer is an outer hair cell from the inner ear. These
guys have on the order of 100 mV across them, and when
the stereocilia ("hairs") at one end are moved by vibration,
they modulate conductance channels and the cell conducts
current at the vibration frequency. That part of the system
is of course going from mechanical to electrical. But in
response to the changing potential across the cell, it changes
its length and actually ends up boosting the mechanical
input signal. As far as I know, there has been no systematic
survey of other tissues to see if they have this
electrical-to-mechanical transduction property, unrelated
to their normal function.

So *in theory* there could be a transduction system.

My question was related to the signal level that could
be present in the first place, given what I supposed
is the Faraday shielding of the conductive tissue of
the head and mouth. I think there must be a way to
compute this, since the same issue would be involved
in (for example) using conductive foams and coatings
on electronic apparatus to get EMC compliance.

Best regards,





Bob Masta
dqatechATdaqartaDOTcom

D A Q A R T A
Data AcQuisition And Real-Time Analysis
www.daqarta.com