Can Sound Be Used As A Weapon?

From LRADs to the dreaded "brown noise," we look at attempts to weaponize sound. Is it possible? What effects can sound have on the body? And how much do we not know? (Hint: The answer is "A lot.")

 

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Episode Transcript

Speaker 1 (00:04):
Welcome to tech Stuff, a production from iHeartRadio. Hey Therein
Welcome to tech Stuff, I'm your host, Jonathan Strickland. I'm
an executive producer with iHeart Podcasts and how the tech
are you? So? On Monday's episode of tech Stuff, I
covered the topic of active noise canceling headphones or active

(00:28):
noise reduction headphones, and I mentioned in that episode the
development of a system designed to cause discomfort in young
people through the use of sound played at a pitch
that most adults can't hear, because as we age, we
start to lose the upper range of our hearing. This
device is called the mosquito. And while I was a

(00:50):
little flippant in the noise canceling episode, the truth is
that acoustic weaponry is a thing. It might potentially cause
significant heart depending on how it is used. And one
of the scariest things about acoustic weaponry is that we
don't actually really know how dangerous or not dangerous it is.

(01:11):
So today I thought i'd talk a little bit about
the history of using sound as a weapon, the technology
created to harness sound in such a way, and the
scholarship or lack thereof, surrounding the topic. Now On the
one hand, sound has undoubtedly been weaponized in the past.
You can't deny that sound has been used as a weapon.

(01:32):
But on the other hand, there remain many questions as
to the efficacy of acoustic weaponry. I guess it depends
upon your intent. There's little doubt that someone could use
sound to cause irritation or even pain in an effort
to say, disperse a crowd. That's been used many times,
especially over the last couple of decades here in the

(01:54):
United States. There are stories about more sinister weapons, ones
that you know, use sound to cause physical trauma up
to and including lethal injury to targets. In fact, according
to one scholarly article on the subject, one that I'll
talk about a lot more in this episode, some stories

(02:14):
allege that through sound and acoustic weapon could induce cavitation
in tissue. That is, the sound could create bubbles within
tissue like your organs, and then those bubbles could implode
and that could cause significant damage. Nothing like the thought of,
you know, liquefying organs. To really spice up your research now,

(02:37):
I think it is very important to add that the
scientific paper I just mentioned, it's titled Acoustic Weapons a
prospective assessment. It was written by Jurgen Altman, and the
author stresses that these are merely allegations. There's a distinct
lack of evidence supporting these kinds of claims. Altman makes

(02:58):
this very clear. Is a long and thorough article, and
I highly recommend you read it. It was originally published
in the scientific journal Science and Global Security, volume nine.
It originally published in two thousand and one. It is
free to read, so if you want to read the
whole thing, you should. It's really a good read. I mean,

(03:18):
it's actually written in a way that's very accessible. I think. Now,
obviously it could be the case that since two thousand
and one there have been more scientific focus directed at
acoustic weaponry. But doing that is kind of tricky because,
for one thing, how do you study potentially traumatic or
even deadly effects of sound on human subjects, Because that's

(03:41):
not exactly an ethical thing to do. If part of
your question is will this hurt someone? If I play
this frequency of sound at this volume putting someone in
the path of that, that's really questionable, not questionable even
I think that's just downright on ethic. Meanwhile, you have
folks in the real world building real stuff that is

(04:07):
weaponizing sound, So we don't fully understand what effect this
could have on people. It may be largely benign apart
from the obvious dangers of like hearing loss and stuff,
but it might be worse. We just don't know. And meanwhile,
we actually have companies making these things and various militaries

(04:30):
and law enforcement agencies using them, so it's kind of scary.
It's almost like the lack of evidence gives cover to
those who are profiting off turning sound into a weapon
because there's no proof showing that these weapons can be lethal, right,
so they're non lethal weapons. They're not causing real harm,

(04:51):
at least that could be the argument. So it should
be totally fine for like a police force to use
a directed acoustic weapon on a group of students who
are testing something on a college campus because it's not lethal.
And if you're thinking that sounds incredibly irresponsible and potentially criminal,
then you're catching on quick. But let's talk about the

(05:12):
history of acoustic weapons. Now. One place that a lot
of articles about the history of acoustic weapons are sound
as a weapon will pick as their starting point is
the biblical account of the Battle of Jericho, which I
think is a fun way to start, but not really helpful.
But yeah. In the in the Bible, the story is

(05:34):
Joshua leads the Israelites to conquer Canaan, and the city
of Jericho's on their to do list, and the big
guy upstairs tells Joshua that he and his army are
to carry the Ark of the Covenant, as featured in
the documentary Raiders of the Lost Arc, and they're going
to have the procession led by seven priests who are
blowing trumpets made of Ram's horn, and they're to do

(05:57):
that for six days, going around the city one time
each day. On the seventh day, they are to march
around the city seven times, blowing the trumpets, and then
afterward letting out a big old whoah, you know, shouting out,
and at that point the city walls will come a tumblin' down,
as Professor Harold Hill would say, now, not to burst

(06:21):
any bubbles. But archaeological digs suggest that while there was
a city in Jericho's spot before this particular period in history,
and there was a city in Jericho's spot after this
particular era of history, during the time when the story
is actually supposed to have taken place, there were no
people living in Jericho. So, in other words, the story's

(06:44):
just a story, but it's a fun one to start with.
So could sonic blasts actually knock down walls? Well, I
would argue that, since this is a biblical story, it's
not really like the pressure wave coming from these trumpets
knocked the walls down. Rather, it's more like God saying,
all right, y'all seem to follow my arbitrary orders I

(07:06):
gave you, so now you get to kill everybody in town,
which you know that's wild, But yeah, I would argue
that the implication here is not that the trumpets knocked
down the walls, but rather it was the big deity
in charge who did the knock and down part. Still,
you can imagine how sound could play a part in war.
You could use sound in order to convey signals across distance.

(07:29):
You could use sound in an attempt to intimidate the enemy.
There's the infamous scene in Apocalypse Now in which a
fleet of helicopters are blasting Wagner's Ride of the Valkyries
as they fire down upon Viet Cong soldiers and Vietnamese
civilians alike. So there's that now, Granted, that's fiction and

(07:53):
people will tell you that didn't really happen, but that's
a popular media depiction of using sound and warfare. Scottish
bagpipes have been used for the purposes of kind of
intimidating foes, as anyone who has heard them up close
inevitably wants to find a way to get away from
that point really quickly. I'm joking, kind of fun. Sign note,

(08:15):
there's a bit of lore in bagpiping that the British
actually outlawed the playing of bagpipes in Scotland around seventeen
forty five as part of a larger disarming act, because
bagpipes have been deemed an instrument of war literally in
this case. But historian John Gibson, in his book Traditional
Gaelic Bagpiping seventeen forty five to nineteen forty five, argues

(08:38):
that the text of this disarmament Act does not actually
name bagpipes as being prohibited, and that pipers who bring
up this era of supposed persecution are probably just tired
of people asking if they could kindly stop that awful racket.
I'm having a lot of fun here, but I think
it's only fair to say I actually kind of like
bagpipe music. Anyway, Sounds played an important role in warfare,

(09:03):
but that's not the same thing as using sound as
an actual weapon. Now, according to Yurigen Altman's research, there's
not much on record of militaries using sound as a
weapon of war, though he did find suggestions that both
Japan and the United Kingdom looked into the possibility of
using acoustic weapons to lethal effect over some distance. Now.

(09:26):
According to that research, both countries ultimately came to the
conclusion that if it were in fact possible to create
a sound so strong as to be lethal, it would
require more power than would be practical. It would make
way more sense to, you know, just use the conventional
weapons we already have at our disposal. Why would you

(09:46):
go and build this thing to get the same result
you would get from weapons we already have. Which makes
me think of Jurassic World. So big spoiler for the
Jurassic World series, although I have a low opinion of
those movies anyway, one of the plot points in that
series is that the military wants to make use of dinosaurs,
essentially using them to be like beasts of war and

(10:09):
using lasers to point at enemies and then the dinosaurs
attack the lasers because they've been trained to do that.
But you know, we've got stuff like guns with laser
sights or bombs and missiles with laser guidance. So it
seems like it's an unnecessary and and practical use of
our time and resources. Anyway, let's get back to sound.
Altman's research included a nineteen sixty nine book titled Riot

(10:33):
Control Material and Techniques by Our Applegate. Now. The book
mentioned that many scientific articles had discussed the use of
acoustic weapons in a non lethal capacity, specifically using low
frequency sounds to counter, say a riot. Now, Altman points
out that he was unable to find evidence of the

(10:55):
mentioned scientific articles. He said, if these articles exist, I
couldn't find them. The book alleges they exist, but I
don't know where. According to Applegate, whomever it was that
looked into using devices to create this low frequency sound
to make this effect to do riot control ultimately determined

(11:16):
it would be too expensive to be practical. Now, some
of that makes sense, because I'm going to talk more
about sound waves and frequencies and wavelengths and stuff later
in this episode. But if you're talking about low frequencies
like below, the threshold of typical human hearing, which at
the low end is around twenty hurts. If you're talking
about below that, well, the sound waves you're talking about

(11:39):
are long. Those wavelengths are pretty long. You're talking about
a low frequency and long wavelengths. High frequency have shorter wavelengths.
With those long wavelengths, you also need a large loud
speaker in order to actually produce those wavelengths. If you've
ever seen the speakers on a stereo system, you know

(12:01):
you've got different types, right, You've got your tweeters, you've
got your subwiffers, that kind of thing. Well, the speakers
responsible for the higher pitches are going to be smaller.
The diaphragm needed to push air around to create those
higher frequency sounds is smaller and needs to move very

(12:21):
quickly in order to do that. The base speaker is
going to be much larger, and it's going to move
more slowly in order to push the air properly to
create those low frequencies. So, if you want to create
a really powerful, very low frequency generator, it's going to
be huge and it's going to require a lot of

(12:42):
power to move that massive diaphragm, especially if you want
to do so at a really high amplitude, as in
a really high volume, that just is going to require
an enormous amount of energy, which is I think one
of the reasons why even if militaries did look at
infra sound as a potential weapon, they ultimately came to
the conclusion that it was impractical because you would have

(13:05):
to build things that are so large and so power
or energy hungry that it just didn't make sense like
you could achieve the same effect through other means without
spending all that time and effort and energy to operate
an impractical weapon. So sound did become important when it
was playing a part in you know, like psychological operations

(13:28):
aka SYOPS. I feel like I should get the stuff.
They don't want you to know, guys on here to
talk about syops because that's kind of right in their
sweet spot. But this gets back to the concept of
using sound in an effort to intimidate the enemy. So
while Apocalypse Now was a fictional use of sound to
get the sort of achievement, there are real world analogs

(13:51):
that used sound or attempted to use sound in ways
to get a very similar result. So, for example, during
the Vietnam War, our US forces used recorded sounds in
an attempt to demoralize Viet Cong soldiers. One such operation
was called Wandering Soul, and this hinged on Vietnamese culture.

(14:12):
So in Vietnam there was a widely held belief. This
is widely held belief that if someone dies and they
do not receive a proper burial, their spirit would be
forced to wander the earth in pain for all eternity.
So the US started blasting a spooky recording of South
Vietnamese people impersonating deceased Viet Cong soldiers, the ghosts of

(14:36):
Viet Cong soldiers who apparently were consigned to this fate.
Some of the recordings included messages urging soldiers to return
home to their families and to abandon the fight. Now,
the effectiveness of this campaign is questionable, as it's pretty
hard to conceal the fact that a helicopter is blasting
out a recorded message as opposed to just believing there's

(14:57):
an actual ghost jamboree going on outside. And nineteen seventy
the US had stopped using this tactic in Vietnam, but
it was an attempt to use sound to intimidate. I'll
talk more about the exploration of acoustic weapons. But first,
let's take a quick break to think our sponsors. All right,

(15:25):
let's get back to Jurigen Altman's work. He did find
some other instances of acoustic weapons in scholarly journals, though
tracking down any hard evidence that any of these things
were ever built and or used was a totally different story.
But one such instance involved a supposed device created by
the British Army in an effort to deal with protesters

(15:47):
in Northern Ireland. The device, nicknamed the squawk Box, produced
two high pitch frequencies within the range of typical human hearing,
although if you're old enough you wouldn't pick up bottom inherently.
One of the pitches was at sixteen killer hurts and
the other was at sixteen point zero zero two killer hurtz.

(16:08):
I probably wouldn't be able to hear these my hearing
tops out somewhere in the fifteen to sixteen killer hurtz range,
at least the last time I tested it. That's where
it was, so I might not perceive this directly at all. However,
at high amplitudes, at high volumes, these higher pitch frequencies
can interact with one another and interfere with one another.

(16:29):
When we talked about noise canceling headphones, I talked about
how this works in that context, where you create a
sound wave that's in opposite to the one that you're
trying to block, and if you're doing that, the two
waves cancel each other out and you get silence or
near silence as a result. So the production of these

(16:50):
two different frequencies would induce a third frequency to form
within the ears of protesters, and the effect was supposedly
so so intense that people couldn't withstand it. They had
to get away from the sound. Altman points out that
the UK has denied that such a device has ever existed,

(17:10):
and he also mentions another source that concluded that while
the British may have looked into actually making such a thing,
it may never have been built. So it sounds like
this is another one of those things where people said,
you know, this should be able to work, but no
one actually made the thing. But it does come into
play when we get to audio spotlights a little later

(17:32):
in this episode, so that's a fun little tidbit. Further,
Altman writes about articles claiming that infrasound you know below
the typical range of human hearing, so below that twenty
Hurtz range, played at a high enough volume, like at
around one hundred decibels, can disorient the listener. But Altman's
research also came across scientists who said they could not

(17:52):
confirm these findings, so whether that's actually true or not
remains unknown. It's kind of funny because you know, this
is an anecdote, so it's not really it's not evidence
at all. But this is something that happened to me
not too long ago. I was in a car with
my partner and a jeep pulled up behind us, and
the person in the jeep had their sound system blasting
at an incredible volume, and the bass was cranked up,

(18:15):
probably about as far as it could go, And even
though we were sitting in a car with our windows
rolled up, we could hear that bass pretty clearly, and
it did create a rather unpleasant and disorienting sensation, though
that might just be because I'm old and cranky and
have nothing to do with any physiological reason. Altman specifically
states that his research focused on acoustic weapons that are

(18:37):
intended to do physical damage to a target, rather than
just using sound as a way to annoy or distress
someone by you know, like preventing them from getting rest,
for example, which is legit. But I think we should
take the use of sound as a deterrent or way
of distressing someone into consideration, because while there is a

(18:59):
lack of firm scholarship on the efficacy of sound as
a weapon that causes direct physical harm or perhaps even death,
we do have plenty of examples of folks using sound
to make someone else's life more difficult. For example, Christmas
nineteen eighty nine, five years after the song do they
Know It's Christmas? Came out? Now, I think there's no

(19:21):
denying that that particular song is torture all by itself,
but it doesn't factor into the story now. In nineteen
eighty nine, the US military used rock and or roll
music to force Manuel Noriega to exit the Vatican embassy
in Panama City, at least that was their intent. So
the US won in Noriega on charges of drug trafficking

(19:43):
and such, and Noriega had sought refuge in the embassy.
So the US put some really powerful speakers on hum v's,
drove the humv's around the embassy, and blasted the embassy
with tunes like I thought the Law by the Clash,
which is classic, or all I what is you by
you too? And because the military really does have a

(20:04):
six sense of humor Hanama by Van Halen. But mostly
they played a lot of songs by guns n' Roses
and the Doors. This musical assault lasted three days, but
then the Pope called the President and said, hey, can
y'all knock it off please? That's our embassy. And the
US complied, and Noriega ultimately surrendered himself just a few

(20:26):
days later. I don't know, maybe he missed the music.
In nineteen ninety three, law enforcement agents employed the let's
blast them with sound technique on David Koresh's compound in Waco, Texas.
This is the infamous Branch Davidian holdout. Now. Among the
sonic bombs that they dropped were various songs as well

(20:47):
as the sound of jet planes and disturbingly, one report said,
the screams of rabbits as they were being slaughtered. Yikes.
Now the military has used loud music to rock the
sleep and morale of prisoners of war as well, in
order to soften them up for interrogation or break down

(21:07):
their resistance by preventing them from getting enough rest, so
mentally they wouldn't be able to withstand interrogation techniques. Now,
I find all of this ethically troubling, to say the least,
particularly in light of research that has suggested repeatedly that
torture is not effective. At least, it's not effective if
your goal is to get at some sort of truth,

(21:30):
no matter how popular media might suggest otherwise. I'm looking
at you, Jack Bauer, But I mean, I guess you
could argue it is effective if your only goal is
to make the tortured person feel miserable and powerless. Yeah,
it works to that extent, but that seems you know, repugnant.
You know, again, not really the same as using a

(21:50):
weapon of war. So what about l rads l RAD
That initialism stands for long range acoustic device, and in
turn these actually evolved from an earlier device, the AHD
or acoustic hailing device. All right, this involves a pretty
tragic story. So back in two thousand, US forces aboard

(22:13):
a Navy destroyer named the USS Coal were attacked when
terrorists aboard a small boat approached the vessel and then
bombed the destroyer. The attack killed more than a dozen
US service members as a result. As the boat was approaching,
the USS Coal attempted to hail the vessel to determine

(22:33):
the crew's intent, but they got no response. There was
no radio contact with the boat, so hailing involved using
loudspeakers to send out a message over the water. But
sound doesn't travel forever. As I mentioned in Monday's episode,
over distance, sound waves attenuate they diminish in strength, so

(22:54):
it was reasonable to assume that the crew on the
smaller boat just couldn't hear the messages. Once the boat
was close enough that those aboard the USS Coal could
be sure that they were being heard, it was already
too late, and the attack immediately followed. One consequence of
this attack was that engineers began to develop technology designed

(23:16):
to focus sound waves and to blast them out at
high enough amplitude or volume so that intelligible sound could
travel much, much further in a directed fashion. This was
the acoustic hailing device, and it would allow naval forces
to send an audible message, not just audible, but intelligible,

(23:36):
as in you can understand what someone is saying, in
order to warn approaching craft that they need to make
their intent clear and follow orders or else potentially face
defensive measures from the Navy. Essentially, the Navy would be
able to say stop where you are, or we will
shoot you now. To accomplish this, the device needed to

(23:58):
be able to one blast out sound with enough energy
enough amplitude to travel a far distance, and two focus
that energy toward the target. And turns out you can
do this with sound. So let's talk about sound beams
or audio spotlights, because this is really cool. All right.

(24:18):
So I mentioned in the previous episode that sound travels
in waves, in longitudinal waves. Actually we talked about that
in the active Noise Canceling episode, but these waves are
pretty darn long. So I'm talking about the wavelengths of
sound that are within the typical range of human hearings,
so between twenty hurts to twenty killer herts. If you

(24:39):
compare those wavelengths to like light waves sound waves in
the audible range, they are enormous. And that link means
that sound waves can and do bend around physical objects.
They diffract. So here's a way of imagining this. Let's
say you're standing on one side of a free standing
opaque wall. Let's say the wall is like eight feet tall.

(25:02):
I'm on the other side of this opaque wall. We
would still be able to talk to each other, right,
You could speak and I could hear you, and I
could speak and you could hear me, even though there's
a wall in the way and we can't see each other. Well,
the light is not able to diffract around the height
of the wall. The light wavelengths are so small they
don't diffract around this wall. But the sound waves are

(25:23):
long enough where they can diffract around the wall. Otherwise,
if they couldn't, we would speak and the sound would
just not be able to cross the wall. It would
go in every other direction and we wouldn't be able
to hear one another. But we know that's not the case.
We know we would be able to hear each other.
If light did that, by the way, it would be
almost like we have X ray vision, But it doesn't

(25:44):
work that way. That same feature, however, this long wavelength
of sound makes it very hard to focus sound into
a beam. Sound on its own would just travel outward
from the source essentially in all directions and lose energy
as it travels, or, if you prefer, the energy disperses
as the sound travels outward from the source. So as

(26:06):
you go further away from where the sound was made,
it gets less audible until you get to a point
where you just can't detect it at all. So how
do you make sure sound is audible from very far away? Well,
one way is you could just keep upping the amplitude,
but that gets dangerous. Also, it would get to a
point where it's so loud that everyone near the audio
device would need some serious air protection, and even then

(26:28):
there's some worry about how those vibrations would affect the
human body. Keep in mind that sound through a gaseous
medium is essentially changes in air pressure, and if you're
blasting stuff out at like one hundred and sixty decibels,
that's massive amounts of air pressure, Like it would feel
like you're getting punched. Now, remember the decibel scale is
also logarithmic. This is something that's hard to get your

(26:52):
mind wrapped around unless you deal with logarithms all the time,
in which case it's easy, but I think for most
people it's not intuitive. So if you have a sound
that's ten decibels, that means that it's ten times louder
than something that's at zero decibels. Zero decibels is a
sound that is barely audible. If you are talking about

(27:13):
a sound that's at twenty decibels, twenty decibels is one
hundred times louder than zero decibels. So once you get
up to around one hundred and twenty decibels, you're talking
about sound that's loud enough to cause permanent hearing damage
or hearing loss. Once you get a little higher, you're
talking about sound that's above the pain threshold. That'd be

(27:33):
around one hundred and forty decibels or so l rads
can go up to one hundred sixty decibels. That's pretty
serious stuff. So it would be great if you could
direct sound in a significant way, one to focus that sound,
and two to prevent the sound from freaking havoc on
your own side. And one way to do that is

(27:54):
through what is called an audio spotlight, which emits sound
at very very high frequencies, frequencies that are much too
high for humans to be able to hear them. In fact,
they're too high for dogs to hear them. Cats could
probably hear them, Bats definitely could, but not so much
with people. I'll explain more after we take this quick

(28:15):
break before the break, I was talking about audio spotlights.
What is an audio spotlight. It's a surface over which
there are are hundreds of transducers that are capable of

(28:36):
emitting sound. And at these frequencies, the sound wave links
are much smaller than in what's in our audible range,
So we're talking about things like in the say sixty
five kilohertz frequency. So these transducers, they're like very tiny
little speakers that are able to move super fast and
super powerful, Like they don't have to be that strong

(28:57):
because they're smaller, so you don't use as much energy
to move the speaker in order to generate sound. But
they are very very tiny, and because the wavelengths that
they are generating are also really tiny, they aren't as
affected by diffraction, So like this is something that acts
more like lightwood than audible sound. So you wouldn't necessarily

(29:19):
be able to pick up these very high frequencies if
there were a wall in the way, because the sound
waves are so small that they wouldn't wrap around the
top of the wall and you wouldn't be able to
detect them on the other side. However, it also means
that the sound will travel in a much more focused way.
You can direct the sound toward a target, But if
you're generating sounds that are well above the range of

(29:41):
human hearing, what good does that do? Right? Like, yeah,
we can shoot a beam of sound waves using this
focused approach, using very very very tiny sound waves, but
if you can't perceive them directly, then what good does
that do? Well? It turns out you can create actual
audit sounds using these higher frequencies, because again, sound waves

(30:04):
at high enough amplitude will interfere with one another. At
low amplitude, they'll just pass through each other, but at
high amplitude they will interfere. So again I talked about
how noise canceling headphones creates destructive interference by creating an
anti phase sound that will cancel out incoming sound. But

(30:26):
it's also true that if you play slightly different ultrasonic frequencies,
their interaction with one another can create frequencies that are
actually in the audible range. I mentioned that supposed project
that the Ministry of Defense of the UK did in
order to dissuade protesters in Northern Ireland, and of course
the Ministry of Defense said they never built that thing.

(30:47):
But since those days we have had people build audio spotlights,
and they work on essentially the same principle. You generate
these different frequencies, maybe even the same frequency, just out
of phase, and through that you can encode information on
top of this frequency, and that information can be within
the audible range. So the audio is not coming or

(31:10):
the audible audios not coming from the speakers themselves. Right,
if you were able to just isolate them playing a
single frequency, you still wouldn't hear anything, even though the
transducers would be generating sound, it would just be beyond our
capability of sensing it. But the interaction of the sound
waves themselves creates the audible sound. It's incredible. It's a

(31:33):
really neat phenomenon. There's actually a great demonstration of this
on YouTube. The channel I saw it on was NPS Physics.
The videos title is audio Spotlight How a audio spotlight works.
That's their grammatical error, not mine. It's actually taken from
a lecture given by doctor Bruce DeNardo, and it's really entertaining.

(31:54):
He's a great lecturer. He's very good at explaining how
this works at a very high level. Does explain it's
much more complicated than he's letting on. But that he's
giving kind of the basic explanation of what's happening, and
they do use the music of the Eagles in their demonstration.
Now I happen to share the same opinion as the

(32:15):
dude from The Big Lebowski on that particular band, except
for Journey of the Sorcerer, which I think is an
awesome instrumental track, and anyone who's familiar with Hitchhiker's Guide
through the Galaxy is probably gonna dig it anyway. Using
this method, it is possible to direct sound, and with
acoustic haaling devices, the intent is to make that sound
intelligible so that oncoming vessels can hear commands to stop

(32:40):
or whatever, or to turn around. But you can also
use the same capability to blast noise that is unpleasant
or unsettling and that segues into the long range acoustic
devices or lriads. These are not necessarily meant for haling purposes,
but for stuff like crowd dispersal, and there are questions

(33:01):
as to whether or not it is ethical to use them,
or should even be legal to use them. There have
been cases in which US law enforcement have used lrad's
l rads for crowd control, blasting out a siren noise
that's usually projecting sound between two and four killer hurts.
Two killer hurts to four killer hurts. That is, that

(33:22):
range is fairly high pitched, and it's unpleasant, especially at
very high volumes. It's this piercing siren kind of sound,
and if it's blasted at you loud enough, it's probably
going to cause at least discomfort. And as I mentioned earlier,
if the amplitude is high enough, like if you have
a decibel level of around one hundred and twenty or more,
and these things are capable of much more than that,

(33:44):
then you could experience hearing loss just from relatively short
exposure to these things. Of course, you could protect yourself
with hearing protection, which actually works pretty darn well. That's
another reason why a lot of militaries have abandoned the
use of acoustic weapons, because if your enemy has ear protection,

(34:05):
then your weapon isn't any good. It doesn't work so great.
Hearing protection will reduce the decimal level enough so that
it's at safe levels. It still probably won't sound great.
You'll still get some of that siren noise in, but
you wouldn't be in as much risk of experiencing actual
hearing loss as a result of that. According to musicology
now dot org, the most powerful acoustic healing devices are

(34:28):
capable of transmitting audible sound from a distance of more
than five kilometers, though most are meant for much shorter distances,
like in the five hundred meter range. But don't get
me wrong. Five hundred meters is still pretty darn far.
I mean, that's more than five American football fields, So
that's a pretty darn good distance to be able to

(34:48):
transmit intelligible sound to a target. And as mentioned, we
still don't really have a full understanding of what this
effect could have on people. Jurgen Altmann research suggests that
folks have made a lot of assumptions without much hard
evidence to back those assumptions up. But that doesn't mean
the assumptions are entirely wrong. It means that we can't

(35:11):
be sure one way or the other without further study.
And study is difficult because if the work could potentially
harm your subjects, that's a huge problem. So can infra sound,
you know, those very low frequency sounds below the range
of human hearing. Can it at a high enough volume
at enough decibels cause stuff like nausea or intestinal pain.

(35:34):
Could it cause the dreaded brown noise, as in a
sound frequency that, when played at a high enough volume,
forces you to evacuate, to defecate, in other words, to
poop yourself. There's no evidence of that, By the way,
doesn't mean it can't happen. I just mean there's no evidence.
So could it cause actual physical trauma? If you were

(35:55):
blasting sound at like, you know, one hundred and fifty decibels,
let's say it's inaudible sound. Maybe it's too low to hear.
Could that very low sound at one hundred and fifty
decibels cause physical harm Could it resonate with your internal
organs causing them to vibrate with enough energy to hurt you.
A resonance, I mean, is a thing. The classic example
of resonance is you tap a crystal glass, like a

(36:18):
champagne glass made out of crystal, and you're gonna hear
it ring out a tone. Actually it rings out several tones.
You get your base tone and then the harmonics of
that tone, but the harmonics have less energy than your
primary tone does. Anyway, if you were to play back
that same base tone, that would induce the crystal champagne

(36:38):
glass to start vibrating. It would vibrate along with this
frequency you're blasting it at, if it was the resonant frequency.
If it's the same frequency that generates when it when
you tap it, if you blast that glass with enough
volume of that tone, then it will cause the glass
to deform to the point where it will shatter. So

(36:59):
this is the class like opera singer causes glass to
break using their voice trick. It's actually pretty hard to
do for most singers. Usually you would need a pretty
significant amount of amplification as well as incredibly good pitch
to manage. It can be done, but usually it requires amplifications.
It's very hard to do with your voice alone anyway.

(37:21):
It's not just champagne flutes made of crystal that resonate.
So the thought is that if you dialed an audio
emitter to the right frequency, one that's low enough to
penetrate the body and strong enough to really get things
moving around in there, you can make a person's inerds
or their air cavities inside their body vibrate. That would
cause that tissue to heat up. Right. Vibration is energy,

(37:44):
and it's like friction essentially, kind of the same way
microwaves end up heating up food when you put them
in the microwave, so of course that's using microwave radiation
per of the electromagnetic spectrum, not acoustic waves. But I
think we can all agree that having your organs all
start to heat up is bad, or maybe induce air
bubbles to form inside tissue that's also really bad. But

(38:07):
as Altman points out repeatedly, there just is an evidence
that this actually happens or has happened, just that there
are a lot of articles that hypothesize maybe it could happen,
So maybe it would, maybe it wouldn't. Finding out would
require deeply unethical research and a cruel disregard for human
safety or animal safety, as it turns out, and it

(38:28):
might mean that the technology necessary to carry out such
an effect would be prohibitively expensive to build and or
operate if you did try to do this. So I
guess that's good news. Altman's article, as I mentioned, it's
free to read. I recommend going through it. It is
quite long, and Alman really did his work trying to
track down reputable research on the topic. The paper is

(38:49):
longer than sixty pages, but again very easy to understand.
So if you have time, check it out. That article
that is really the basis for a lot of what
this episode is all about, although again I went off
book for the stuff that was about disrupting someone's sleep
cycles or whatever. The article again, its title is Acoustic
Weapons a Prospective Assessment. It's in Science and Global Security,

(39:12):
Volume nine, two thousand and one, so check that out. Anyway,
Acoustic weapons remain a thing. I still think it's really
scary that we have these things that are in active
use and we don't have a full understanding of the
effects of that technology and how harmful they may or
may not be. It may turn out that they're relatively

(39:33):
not harmful at all, as long as your exposure to
them isn't too long. But it could also turn out
that they cause some pretty gnarly effects. There's the whole
havana syndrome thing that I didn't get into. I'm sure
the stuff they don't want you to know. Crew has
done an episode on the havana syndrome. I'll have to
reach out to them to make sure, but it would
be weird if they hadn't. Anyway, I hope that you

(39:56):
found this episode interesting. I hope you go check out
that article. Read up on this subject, Read up on
acoustic spotlights. Those things are cool. What a neat way
to create this effect, Like to be able to use
sound that's not in our audible spectrum to create audible
sounds at a point in the distance. That's just incredible

(40:18):
to me, Like it's phenomenal. It blows my mind. In
the meantime, I hope all of you out there are
doing well and I will talk to you again really soon.
Tech Stuff is an iHeartRadio production. For more podcasts from iHeartRadio,

(40:40):
visit the iHeartRadio app, Apple Podcasts, or wherever you listen
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