Speaker 1: Welcome to tech Stuff, a production from iHeartRadio. Hey Therein
Speaker 1: Welcome to tech Stuff, I'm your host, Jonathan Strickland. I'm
Speaker 1: an executive producer with iHeart Podcasts and how the tech
Speaker 1: are you? So? On Monday's episode of tech Stuff, I
Speaker 1: covered the topic of active noise canceling headphones or active
Speaker 1: noise reduction headphones, and I mentioned in that episode the
Speaker 1: development of a system designed to cause discomfort in young
Speaker 1: people through the use of sound played at a pitch
Speaker 1: that most adults can't hear, because as we age, we
Speaker 1: start to lose the upper range of our hearing. This
Speaker 1: device is called the mosquito. And while I was a
Speaker 1: little flippant in the noise canceling episode, the truth is
Speaker 1: that acoustic weaponry is a thing. It might potentially cause
Speaker 1: significant heart depending on how it is used. And one
Speaker 1: of the scariest things about acoustic weaponry is that we
Speaker 1: don't actually really know how dangerous or not dangerous it is.
Speaker 1: So today I thought i'd talk a little bit about
Speaker 1: the history of using sound as a weapon, the technology
Speaker 1: created to harness sound in such a way, and the
Speaker 1: scholarship or lack thereof, surrounding the topic. Now On the
Speaker 1: one hand, sound has undoubtedly been weaponized in the past.
Speaker 1: You can't deny that sound has been used as a weapon.
Speaker 1: But on the other hand, there remain many questions as
Speaker 1: to the efficacy of acoustic weaponry. I guess it depends
Speaker 1: upon your intent. There's little doubt that someone could use
Speaker 1: sound to cause irritation or even pain in an effort
Speaker 1: to say, disperse a crowd. That's been used many times,
Speaker 1: especially over the last couple of decades here in the
Speaker 1: United States. There are stories about more sinister weapons, ones
Speaker 1: that you know, use sound to cause physical trauma up
Speaker 1: to and including lethal injury to targets. In fact, according
Speaker 1: to one scholarly article on the subject, one that I'll
Speaker 1: talk about a lot more in this episode, some stories
Speaker 1: allege that through sound and acoustic weapon could induce cavitation
Speaker 1: in tissue. That is, the sound could create bubbles within
Speaker 1: tissue like your organs, and then those bubbles could implode
Speaker 1: and that could cause significant damage. Nothing like the thought of,
Speaker 1: you know, liquefying organs. To really spice up your research now,
Speaker 1: I think it is very important to add that the
Speaker 1: scientific paper I just mentioned, it's titled Acoustic Weapons a
Speaker 1: prospective assessment. It was written by Jurgen Altman, and the
Speaker 1: author stresses that these are merely allegations. There's a distinct
Speaker 1: lack of evidence supporting these kinds of claims. Altman makes
Speaker 1: this very clear. Is a long and thorough article, and
Speaker 1: I highly recommend you read it. It was originally published
Speaker 1: in the scientific journal Science and Global Security, volume nine.
Speaker 1: It originally published in two thousand and one. It is
Speaker 1: free to read, so if you want to read the
Speaker 1: whole thing, you should. It's really a good read. I mean,
Speaker 1: it's actually written in a way that's very accessible. I think. Now,
Speaker 1: obviously it could be the case that since two thousand
Speaker 1: and one there have been more scientific focus directed at
Speaker 1: acoustic weaponry. But doing that is kind of tricky because,
Speaker 1: for one thing, how do you study potentially traumatic or
Speaker 1: even deadly effects of sound on human subjects, Because that's
Speaker 1: not exactly an ethical thing to do. If part of
Speaker 1: your question is will this hurt someone? If I play
Speaker 1: this frequency of sound at this volume putting someone in
Speaker 1: the path of that, that's really questionable, not questionable even
Speaker 1: I think that's just downright on ethic. Meanwhile, you have
Speaker 1: folks in the real world building real stuff that is
Speaker 1: weaponizing sound, So we don't fully understand what effect this
Speaker 1: could have on people. It may be largely benign apart
Speaker 1: from the obvious dangers of like hearing loss and stuff,
Speaker 1: but it might be worse. We just don't know. And meanwhile,
Speaker 1: we actually have companies making these things and various militaries
Speaker 1: and law enforcement agencies using them, so it's kind of scary.
Speaker 1: It's almost like the lack of evidence gives cover to
Speaker 1: those who are profiting off turning sound into a weapon
Speaker 1: because there's no proof showing that these weapons can be lethal, right,
Speaker 1: so they're non lethal weapons. They're not causing real harm,
Speaker 1: at least that could be the argument. So it should
Speaker 1: be totally fine for like a police force to use
Speaker 1: a directed acoustic weapon on a group of students who
Speaker 1: are testing something on a college campus because it's not lethal.
Speaker 1: And if you're thinking that sounds incredibly irresponsible and potentially criminal,
Speaker 1: then you're catching on quick. But let's talk about the
Speaker 1: history of acoustic weapons. Now. One place that a lot
Speaker 1: of articles about the history of acoustic weapons are sound
Speaker 1: as a weapon will pick as their starting point is
Speaker 1: the biblical account of the Battle of Jericho, which I
Speaker 1: think is a fun way to start, but not really helpful.
Speaker 1: But yeah. In the in the Bible, the story is
Speaker 1: Joshua leads the Israelites to conquer Canaan, and the city
Speaker 1: of Jericho's on their to do list, and the big
Speaker 1: guy upstairs tells Joshua that he and his army are
Speaker 1: to carry the Ark of the Covenant, as featured in
Speaker 1: the documentary Raiders of the Lost Arc, and they're going
Speaker 1: to have the procession led by seven priests who are
Speaker 1: blowing trumpets made of Ram's horn, and they're to do
Speaker 1: that for six days, going around the city one time
Speaker 1: each day. On the seventh day, they are to march
Speaker 1: around the city seven times, blowing the trumpets, and then
Speaker 1: afterward letting out a big old whoah, you know, shouting out,
Speaker 1: and at that point the city walls will come a tumblin' down,
Speaker 1: as Professor Harold Hill would say, now, not to burst
Speaker 1: any bubbles. But archaeological digs suggest that while there was
Speaker 1: a city in Jericho's spot before this particular period in history,
Speaker 1: and there was a city in Jericho's spot after this
Speaker 1: particular era of history, during the time when the story
Speaker 1: is actually supposed to have taken place, there were no
Speaker 1: people living in Jericho. So, in other words, the story's
Speaker 1: just a story, but it's a fun one to start with.
Speaker 1: So could sonic blasts actually knock down walls? Well, I
Speaker 1: would argue that, since this is a biblical story, it's
Speaker 1: not really like the pressure wave coming from these trumpets
Speaker 1: knocked the walls down. Rather, it's more like God saying,
Speaker 1: all right, y'all seem to follow my arbitrary orders I
Speaker 1: gave you, so now you get to kill everybody in town,
Speaker 1: which you know that's wild, But yeah, I would argue
Speaker 1: that the implication here is not that the trumpets knocked
Speaker 1: down the walls, but rather it was the big deity
Speaker 1: in charge who did the knock and down part. Still,
Speaker 1: you can imagine how sound could play a part in war.
Speaker 1: You could use sound in order to convey signals across distance.
Speaker 1: You could use sound in an attempt to intimidate the enemy.
Speaker 1: There's the infamous scene in Apocalypse Now in which a
Speaker 1: fleet of helicopters are blasting Wagner's Ride of the Valkyries
Speaker 1: as they fire down upon Viet Cong soldiers and Vietnamese
Speaker 1: civilians alike. So there's that now, Granted, that's fiction and
Speaker 1: people will tell you that didn't really happen, but that's
Speaker 1: a popular media depiction of using sound and warfare. Scottish
Speaker 1: bagpipes have been used for the purposes of kind of
Speaker 1: intimidating foes, as anyone who has heard them up close
Speaker 1: inevitably wants to find a way to get away from
Speaker 1: that point really quickly. I'm joking, kind of fun. Sign note,
Speaker 1: there's a bit of lore in bagpiping that the British
Speaker 1: actually outlawed the playing of bagpipes in Scotland around seventeen
Speaker 1: forty five as part of a larger disarming act, because
Speaker 1: bagpipes have been deemed an instrument of war literally in
Speaker 1: this case. But historian John Gibson, in his book Traditional
Speaker 1: Gaelic Bagpiping seventeen forty five to nineteen forty five, argues
Speaker 1: that the text of this disarmament Act does not actually
Speaker 1: name bagpipes as being prohibited, and that pipers who bring
Speaker 1: up this era of supposed persecution are probably just tired
Speaker 1: of people asking if they could kindly stop that awful racket.
Speaker 1: I'm having a lot of fun here, but I think
Speaker 1: it's only fair to say I actually kind of like
Speaker 1: bagpipe music. Anyway, Sounds played an important role in warfare,
Speaker 1: but that's not the same thing as using sound as
Speaker 1: an actual weapon. Now, according to Yurigen Altman's research, there's
Speaker 1: not much on record of militaries using sound as a
Speaker 1: weapon of war, though he did find suggestions that both
Speaker 1: Japan and the United Kingdom looked into the possibility of
Speaker 1: using acoustic weapons to lethal effect over some distance. Now.
Speaker 1: According to that research, both countries ultimately came to the
Speaker 1: conclusion that if it were in fact possible to create
Speaker 1: a sound so strong as to be lethal, it would
Speaker 1: require more power than would be practical. It would make
Speaker 1: way more sense to, you know, just use the conventional
Speaker 1: weapons we already have at our disposal. Why would you
Speaker 1: go and build this thing to get the same result
Speaker 1: you would get from weapons we already have. Which makes
Speaker 1: me think of Jurassic World. So big spoiler for the
Speaker 1: Jurassic World series, although I have a low opinion of
Speaker 1: those movies anyway, one of the plot points in that
Speaker 1: series is that the military wants to make use of dinosaurs,
Speaker 1: essentially using them to be like beasts of war and
Speaker 1: using lasers to point at enemies and then the dinosaurs
Speaker 1: attack the lasers because they've been trained to do that.
Speaker 1: But you know, we've got stuff like guns with laser
Speaker 1: sights or bombs and missiles with laser guidance. So it
Speaker 1: seems like it's an unnecessary and and practical use of
Speaker 1: our time and resources. Anyway, let's get back to sound.
Speaker 1: Altman's research included a nineteen sixty nine book titled Riot
Speaker 1: Control Material and Techniques by Our Applegate. Now. The book
Speaker 1: mentioned that many scientific articles had discussed the use of
Speaker 1: acoustic weapons in a non lethal capacity, specifically using low
Speaker 1: frequency sounds to counter, say a riot. Now, Altman points
Speaker 1: out that he was unable to find evidence of the
Speaker 1: mentioned scientific articles. He said, if these articles exist, I
Speaker 1: couldn't find them. The book alleges they exist, but I
Speaker 1: don't know where. According to Applegate, whomever it was that
Speaker 1: looked into using devices to create this low frequency sound
Speaker 1: to make this effect to do riot control ultimately determined
Speaker 1: it would be too expensive to be practical. Now, some
Speaker 1: of that makes sense, because I'm going to talk more
Speaker 1: about sound waves and frequencies and wavelengths and stuff later
Speaker 1: in this episode. But if you're talking about low frequencies
Speaker 1: like below, the threshold of typical human hearing, which at
Speaker 1: the low end is around twenty hurts. If you're talking
Speaker 1: about below that, well, the sound waves you're talking about
Speaker 1: are long. Those wavelengths are pretty long. You're talking about
Speaker 1: a low frequency and long wavelengths. High frequency have shorter wavelengths.
Speaker 1: With those long wavelengths, you also need a large loud
Speaker 1: speaker in order to actually produce those wavelengths. If you've
Speaker 1: ever seen the speakers on a stereo system, you know
Speaker 1: you've got different types, right, You've got your tweeters, you've
Speaker 1: got your subwiffers, that kind of thing. Well, the speakers
Speaker 1: responsible for the higher pitches are going to be smaller.
Speaker 1: The diaphragm needed to push air around to create those
Speaker 1: higher frequency sounds is smaller and needs to move very
Speaker 1: quickly in order to do that. The base speaker is
Speaker 1: going to be much larger, and it's going to move
Speaker 1: more slowly in order to push the air properly to
Speaker 1: create those low frequencies. So, if you want to create
Speaker 1: a really powerful, very low frequency generator, it's going to
Speaker 1: be huge and it's going to require a lot of
Speaker 1: power to move that massive diaphragm, especially if you want
Speaker 1: to do so at a really high amplitude, as in
Speaker 1: a really high volume, that just is going to require
Speaker 1: an enormous amount of energy, which is I think one
Speaker 1: of the reasons why even if militaries did look at
Speaker 1: infra sound as a potential weapon, they ultimately came to
Speaker 1: the conclusion that it was impractical because you would have
Speaker 1: to build things that are so large and so power
Speaker 1: or energy hungry that it just didn't make sense like
Speaker 1: you could achieve the same effect through other means without
Speaker 1: spending all that time and effort and energy to operate
Speaker 1: an impractical weapon. So sound did become important when it
Speaker 1: was playing a part in you know, like psychological operations
Speaker 1: aka SYOPS. I feel like I should get the stuff.
Speaker 1: They don't want you to know, guys on here to
Speaker 1: talk about syops because that's kind of right in their
Speaker 1: sweet spot. But this gets back to the concept of
Speaker 1: using sound in an effort to intimidate the enemy. So
Speaker 1: while Apocalypse Now was a fictional use of sound to
Speaker 1: get the sort of achievement, there are real world analogs
Speaker 1: that used sound or attempted to use sound in ways
Speaker 1: to get a very similar result. So, for example, during
Speaker 1: the Vietnam War, our US forces used recorded sounds in
Speaker 1: an attempt to demoralize Viet Cong soldiers. One such operation
Speaker 1: was called Wandering Soul, and this hinged on Vietnamese culture.
Speaker 1: So in Vietnam there was a widely held belief. This
Speaker 1: is widely held belief that if someone dies and they
Speaker 1: do not receive a proper burial, their spirit would be
Speaker 1: forced to wander the earth in pain for all eternity.
Speaker 1: So the US started blasting a spooky recording of South
Speaker 1: Vietnamese people impersonating deceased Viet Cong soldiers, the ghosts of
Speaker 1: Viet Cong soldiers who apparently were consigned to this fate.
Speaker 1: Some of the recordings included messages urging soldiers to return
Speaker 1: home to their families and to abandon the fight. Now,
Speaker 1: the effectiveness of this campaign is questionable, as it's pretty
Speaker 1: hard to conceal the fact that a helicopter is blasting
Speaker 1: out a recorded message as opposed to just believing there's
Speaker 1: an actual ghost jamboree going on outside. And nineteen seventy
Speaker 1: the US had stopped using this tactic in Vietnam, but
Speaker 1: it was an attempt to use sound to intimidate. I'll
Speaker 1: talk more about the exploration of acoustic weapons. But first,
Speaker 1: let's take a quick break to think our sponsors. All right,
Speaker 1: let's get back to Jurigen Altman's work. He did find
Speaker 1: some other instances of acoustic weapons in scholarly journals, though
Speaker 1: tracking down any hard evidence that any of these things
Speaker 1: were ever built and or used was a totally different story.
Speaker 1: But one such instance involved a supposed device created by
Speaker 1: the British Army in an effort to deal with protesters
Speaker 1: in Northern Ireland. The device, nicknamed the squawk Box, produced
Speaker 1: two high pitch frequencies within the range of typical human hearing,
Speaker 1: although if you're old enough you wouldn't pick up bottom inherently.
Speaker 1: One of the pitches was at sixteen killer hurts and
Speaker 1: the other was at sixteen point zero zero two killer hurtz.
Speaker 1: I probably wouldn't be able to hear these my hearing
Speaker 1: tops out somewhere in the fifteen to sixteen killer hurtz range,
Speaker 1: at least the last time I tested it. That's where
Speaker 1: it was, so I might not perceive this directly at all. However,
Speaker 1: at high amplitudes, at high volumes, these higher pitch frequencies
Speaker 1: can interact with one another and interfere with one another.
Speaker 1: When we talked about noise canceling headphones, I talked about
Speaker 1: how this works in that context, where you create a
Speaker 1: sound wave that's in opposite to the one that you're
Speaker 1: trying to block, and if you're doing that, the two
Speaker 1: waves cancel each other out and you get silence or
Speaker 1: near silence as a result. So the production of these
Speaker 1: two different frequencies would induce a third frequency to form
Speaker 1: within the ears of protesters, and the effect was supposedly
Speaker 1: so so intense that people couldn't withstand it. They had
Speaker 1: to get away from the sound. Altman points out that
Speaker 1: the UK has denied that such a device has ever existed,
Speaker 1: and he also mentions another source that concluded that while
Speaker 1: the British may have looked into actually making such a thing,
Speaker 1: it may never have been built. So it sounds like
Speaker 1: this is another one of those things where people said,
Speaker 1: you know, this should be able to work, but no
Speaker 1: one actually made the thing. But it does come into
Speaker 1: play when we get to audio spotlights a little later
Speaker 1: in this episode, so that's a fun little tidbit. Further,
Speaker 1: Altman writes about articles claiming that infrasound you know below
Speaker 1: the typical range of human hearing, so below that twenty
Speaker 1: Hurtz range, played at a high enough volume, like at
Speaker 1: around one hundred decibels, can disorient the listener. But Altman's
Speaker 1: research also came across scientists who said they could not
Speaker 1: confirm these findings, so whether that's actually true or not
Speaker 1: remains unknown. It's kind of funny because you know, this
Speaker 1: is an anecdote, so it's not really it's not evidence
Speaker 1: at all. But this is something that happened to me
Speaker 1: not too long ago. I was in a car with
Speaker 1: my partner and a jeep pulled up behind us, and
Speaker 1: the person in the jeep had their sound system blasting
Speaker 1: at an incredible volume, and the bass was cranked up,
Speaker 1: probably about as far as it could go, And even
Speaker 1: though we were sitting in a car with our windows
Speaker 1: rolled up, we could hear that bass pretty clearly, and
Speaker 1: it did create a rather unpleasant and disorienting sensation, though
Speaker 1: that might just be because I'm old and cranky and
Speaker 1: have nothing to do with any physiological reason. Altman specifically
Speaker 1: states that his research focused on acoustic weapons that are
Speaker 1: intended to do physical damage to a target, rather than
Speaker 1: just using sound as a way to annoy or distress
Speaker 1: someone by you know, like preventing them from getting rest,
Speaker 1: for example, which is legit. But I think we should
Speaker 1: take the use of sound as a deterrent or way
Speaker 1: of distressing someone into consideration, because while there is a
Speaker 1: lack of firm scholarship on the efficacy of sound as
Speaker 1: a weapon that causes direct physical harm or perhaps even death,
Speaker 1: we do have plenty of examples of folks using sound
Speaker 1: to make someone else's life more difficult. For example, Christmas
Speaker 1: nineteen eighty nine, five years after the song do they
Speaker 1: Know It's Christmas? Came out? Now, I think there's no
Speaker 1: denying that that particular song is torture all by itself,
Speaker 1: but it doesn't factor into the story now. In nineteen
Speaker 1: eighty nine, the US military used rock and or roll
Speaker 1: music to force Manuel Noriega to exit the Vatican embassy
Speaker 1: in Panama City, at least that was their intent. So
Speaker 1: the US won in Noriega on charges of drug trafficking
Speaker 1: and such, and Noriega had sought refuge in the embassy.
Speaker 1: So the US put some really powerful speakers on hum v's,
Speaker 1: drove the humv's around the embassy, and blasted the embassy
Speaker 1: with tunes like I thought the Law by the Clash,
Speaker 1: which is classic, or all I what is you by
Speaker 1: you too? And because the military really does have a
Speaker 1: six sense of humor Hanama by Van Halen. But mostly
Speaker 1: they played a lot of songs by guns n' Roses
Speaker 1: and the Doors. This musical assault lasted three days, but
Speaker 1: then the Pope called the President and said, hey, can
Speaker 1: y'all knock it off please? That's our embassy. And the
Speaker 1: US complied, and Noriega ultimately surrendered himself just a few
Speaker 1: days later. I don't know, maybe he missed the music.
Speaker 1: In nineteen ninety three, law enforcement agents employed the let's
Speaker 1: blast them with sound technique on David Koresh's compound in Waco, Texas.
Speaker 1: This is the infamous Branch Davidian holdout. Now. Among the
Speaker 1: sonic bombs that they dropped were various songs as well
Speaker 1: as the sound of jet planes and disturbingly, one report said,
Speaker 1: the screams of rabbits as they were being slaughtered. Yikes.
Speaker 1: Now the military has used loud music to rock the
Speaker 1: sleep and morale of prisoners of war as well, in
Speaker 1: order to soften them up for interrogation or break down
Speaker 1: their resistance by preventing them from getting enough rest, so
Speaker 1: mentally they wouldn't be able to withstand interrogation techniques. Now,
Speaker 1: I find all of this ethically troubling, to say the least,
Speaker 1: particularly in light of research that has suggested repeatedly that
Speaker 1: torture is not effective. At least, it's not effective if
Speaker 1: your goal is to get at some sort of truth,
Speaker 1: no matter how popular media might suggest otherwise. I'm looking
Speaker 1: at you, Jack Bauer, But I mean, I guess you
Speaker 1: could argue it is effective if your only goal is
Speaker 1: to make the tortured person feel miserable and powerless. Yeah,
Speaker 1: it works to that extent, but that seems you know, repugnant.
Speaker 1: You know, again, not really the same as using a
Speaker 1: weapon of war. So what about l rads l RAD
Speaker 1: That initialism stands for long range acoustic device, and in
Speaker 1: turn these actually evolved from an earlier device, the AHD
Speaker 1: or acoustic hailing device. All right, this involves a pretty
Speaker 1: tragic story. So back in two thousand, US forces aboard
Speaker 1: a Navy destroyer named the USS Coal were attacked when
Speaker 1: terrorists aboard a small boat approached the vessel and then
Speaker 1: bombed the destroyer. The attack killed more than a dozen
Speaker 1: US service members as a result. As the boat was approaching,
Speaker 1: the USS Coal attempted to hail the vessel to determine
Speaker 1: the crew's intent, but they got no response. There was
Speaker 1: no radio contact with the boat, so hailing involved using
Speaker 1: loudspeakers to send out a message over the water. But
Speaker 1: sound doesn't travel forever. As I mentioned in Monday's episode,
Speaker 1: over distance, sound waves attenuate they diminish in strength, so
Speaker 1: it was reasonable to assume that the crew on the
Speaker 1: smaller boat just couldn't hear the messages. Once the boat
Speaker 1: was close enough that those aboard the USS Coal could
Speaker 1: be sure that they were being heard, it was already
Speaker 1: too late, and the attack immediately followed. One consequence of
Speaker 1: this attack was that engineers began to develop technology designed
Speaker 1: to focus sound waves and to blast them out at
Speaker 1: high enough amplitude or volume so that intelligible sound could
Speaker 1: travel much, much further in a directed fashion. This was
Speaker 1: the acoustic hailing device, and it would allow naval forces
Speaker 1: to send an audible message, not just audible, but intelligible,
Speaker 1: as in you can understand what someone is saying, in
Speaker 1: order to warn approaching craft that they need to make
Speaker 1: their intent clear and follow orders or else potentially face
Speaker 1: defensive measures from the Navy. Essentially, the Navy would be
Speaker 1: able to say stop where you are, or we will
Speaker 1: shoot you now. To accomplish this, the device needed to
Speaker 1: be able to one blast out sound with enough energy
Speaker 1: enough amplitude to travel a far distance, and two focus
Speaker 1: that energy toward the target. And turns out you can
Speaker 1: do this with sound. So let's talk about sound beams
Speaker 1: or audio spotlights, because this is really cool. All right.
Speaker 1: So I mentioned in the previous episode that sound travels
Speaker 1: in waves, in longitudinal waves. Actually we talked about that
Speaker 1: in the active Noise Canceling episode, but these waves are
Speaker 1: pretty darn long. So I'm talking about the wavelengths of
Speaker 1: sound that are within the typical range of human hearings,
Speaker 1: so between twenty hurts to twenty killer herts. If you
Speaker 1: compare those wavelengths to like light waves sound waves in
Speaker 1: the audible range, they are enormous. And that link means
Speaker 1: that sound waves can and do bend around physical objects.
Speaker 1: They diffract. So here's a way of imagining this. Let's
Speaker 1: say you're standing on one side of a free standing
Speaker 1: opaque wall. Let's say the wall is like eight feet tall.
Speaker 1: I'm on the other side of this opaque wall. We
Speaker 1: would still be able to talk to each other, right,
Speaker 1: You could speak and I could hear you, and I
Speaker 1: could speak and you could hear me, even though there's
Speaker 1: a wall in the way and we can't see each other. Well,
Speaker 1: the light is not able to diffract around the height
Speaker 1: of the wall. The light wavelengths are so small they
Speaker 1: don't diffract around this wall. But the sound waves are
Speaker 1: long enough where they can diffract around the wall. Otherwise,
Speaker 1: if they couldn't, we would speak and the sound would
Speaker 1: just not be able to cross the wall. It would
Speaker 1: go in every other direction and we wouldn't be able
Speaker 1: to hear one another. But we know that's not the case.
Speaker 1: We know we would be able to hear each other.
Speaker 1: If light did that, by the way, it would be
Speaker 1: almost like we have X ray vision, But it doesn't
Speaker 1: work that way. That same feature, however, this long wavelength
Speaker 1: of sound makes it very hard to focus sound into
Speaker 1: a beam. Sound on its own would just travel outward
Speaker 1: from the source essentially in all directions and lose energy
Speaker 1: as it travels, or, if you prefer, the energy disperses
Speaker 1: as the sound travels outward from the source. So as
Speaker 1: you go further away from where the sound was made,
Speaker 1: it gets less audible until you get to a point
Speaker 1: where you just can't detect it at all. So how
Speaker 1: do you make sure sound is audible from very far away? Well,
Speaker 1: one way is you could just keep upping the amplitude,
Speaker 1: but that gets dangerous. Also, it would get to a
Speaker 1: point where it's so loud that everyone near the audio
Speaker 1: device would need some serious air protection, and even then
Speaker 1: there's some worry about how those vibrations would affect the
Speaker 1: human body. Keep in mind that sound through a gaseous
Speaker 1: medium is essentially changes in air pressure, and if you're
Speaker 1: blasting stuff out at like one hundred and sixty decibels,
Speaker 1: that's massive amounts of air pressure, Like it would feel
Speaker 1: like you're getting punched. Now, remember the decibel scale is
Speaker 1: also logarithmic. This is something that's hard to get your
Speaker 1: mind wrapped around unless you deal with logarithms all the time,
Speaker 1: in which case it's easy, but I think for most
Speaker 1: people it's not intuitive. So if you have a sound
Speaker 1: that's ten decibels, that means that it's ten times louder
Speaker 1: than something that's at zero decibels. Zero decibels is a
Speaker 1: sound that is barely audible. If you are talking about
Speaker 1: a sound that's at twenty decibels, twenty decibels is one
Speaker 1: hundred times louder than zero decibels. So once you get
Speaker 1: up to around one hundred and twenty decibels, you're talking
Speaker 1: about sound that's loud enough to cause permanent hearing damage
Speaker 1: or hearing loss. Once you get a little higher, you're
Speaker 1: talking about sound that's above the pain threshold. That'd be
Speaker 1: around one hundred and forty decibels or so l rads
Speaker 1: can go up to one hundred sixty decibels. That's pretty
Speaker 1: serious stuff. So it would be great if you could
Speaker 1: direct sound in a significant way, one to focus that sound,
Speaker 1: and two to prevent the sound from freaking havoc on
Speaker 1: your own side. And one way to do that is
Speaker 1: through what is called an audio spotlight, which emits sound
Speaker 1: at very very high frequencies, frequencies that are much too
Speaker 1: high for humans to be able to hear them. In fact,
Speaker 1: they're too high for dogs to hear them. Cats could
Speaker 1: probably hear them, Bats definitely could, but not so much
Speaker 1: with people. I'll explain more after we take this quick
Speaker 1: break before the break, I was talking about audio spotlights.
Speaker 1: What is an audio spotlight. It's a surface over which
Speaker 1: there are are hundreds of transducers that are capable of
Speaker 1: emitting sound. And at these frequencies, the sound wave links
Speaker 1: are much smaller than in what's in our audible range,
Speaker 1: So we're talking about things like in the say sixty
Speaker 1: five kilohertz frequency. So these transducers, they're like very tiny
Speaker 1: little speakers that are able to move super fast and
Speaker 1: super powerful, Like they don't have to be that strong
Speaker 1: because they're smaller, so you don't use as much energy
Speaker 1: to move the speaker in order to generate sound. But
Speaker 1: they are very very tiny, and because the wavelengths that
Speaker 1: they are generating are also really tiny, they aren't as
Speaker 1: affected by diffraction, So like this is something that acts
Speaker 1: more like lightwood than audible sound. So you wouldn't necessarily
Speaker 1: be able to pick up these very high frequencies if
Speaker 1: there were a wall in the way, because the sound
Speaker 1: waves are so small that they wouldn't wrap around the
Speaker 1: top of the wall and you wouldn't be able to
Speaker 1: detect them on the other side. However, it also means
Speaker 1: that the sound will travel in a much more focused way.
Speaker 1: You can direct the sound toward a target, But if
Speaker 1: you're generating sounds that are well above the range of
Speaker 1: human hearing, what good does that do? Right? Like, yeah,
Speaker 1: we can shoot a beam of sound waves using this
Speaker 1: focused approach, using very very very tiny sound waves, but
Speaker 1: if you can't perceive them directly, then what good does
Speaker 1: that do? Well? It turns out you can create actual
Speaker 1: audit sounds using these higher frequencies, because again, sound waves
Speaker 1: at high enough amplitude will interfere with one another. At
Speaker 1: low amplitude, they'll just pass through each other, but at
Speaker 1: high amplitude they will interfere. So again I talked about
Speaker 1: how noise canceling headphones creates destructive interference by creating an
Speaker 1: anti phase sound that will cancel out incoming sound. But
Speaker 1: it's also true that if you play slightly different ultrasonic frequencies,
Speaker 1: their interaction with one another can create frequencies that are
Speaker 1: actually in the audible range. I mentioned that supposed project
Speaker 1: that the Ministry of Defense of the UK did in
Speaker 1: order to dissuade protesters in Northern Ireland, and of course
Speaker 1: the Ministry of Defense said they never built that thing.
Speaker 1: But since those days we have had people build audio spotlights,
Speaker 1: and they work on essentially the same principle. You generate
Speaker 1: these different frequencies, maybe even the same frequency, just out
Speaker 1: of phase, and through that you can encode information on
Speaker 1: top of this frequency, and that information can be within
Speaker 1: the audible range. So the audio is not coming or
Speaker 1: the audible audios not coming from the speakers themselves. Right,
Speaker 1: if you were able to just isolate them playing a
Speaker 1: single frequency, you still wouldn't hear anything, even though the
Speaker 1: transducers would be generating sound, it would just be beyond our
Speaker 1: capability of sensing it. But the interaction of the sound
Speaker 1: waves themselves creates the audible sound. It's incredible. It's a
Speaker 1: really neat phenomenon. There's actually a great demonstration of this
Speaker 1: on YouTube. The channel I saw it on was NPS Physics.
Speaker 1: The videos title is audio Spotlight How a audio spotlight works.
Speaker 1: That's their grammatical error, not mine. It's actually taken from
Speaker 1: a lecture given by doctor Bruce DeNardo, and it's really entertaining.
Speaker 1: He's a great lecturer. He's very good at explaining how
Speaker 1: this works at a very high level. Does explain it's
Speaker 1: much more complicated than he's letting on. But that he's
Speaker 1: giving kind of the basic explanation of what's happening, and
Speaker 1: they do use the music of the Eagles in their demonstration.
Speaker 1: Now I happen to share the same opinion as the
Speaker 1: dude from The Big Lebowski on that particular band, except
Speaker 1: for Journey of the Sorcerer, which I think is an
Speaker 1: awesome instrumental track, and anyone who's familiar with Hitchhiker's Guide
Speaker 1: through the Galaxy is probably gonna dig it anyway. Using
Speaker 1: this method, it is possible to direct sound, and with
Speaker 1: acoustic haaling devices, the intent is to make that sound
Speaker 1: intelligible so that oncoming vessels can hear commands to stop
Speaker 1: or whatever, or to turn around. But you can also
Speaker 1: use the same capability to blast noise that is unpleasant
Speaker 1: or unsettling and that segues into the long range acoustic
Speaker 1: devices or lriads. These are not necessarily meant for haling purposes,
Speaker 1: but for stuff like crowd dispersal, and there are questions
Speaker 1: as to whether or not it is ethical to use them,
Speaker 1: or should even be legal to use them. There have
Speaker 1: been cases in which US law enforcement have used lrad's
Speaker 1: l rads for crowd control, blasting out a siren noise
Speaker 1: that's usually projecting sound between two and four killer hurts.
Speaker 1: Two killer hurts to four killer hurts. That is, that
Speaker 1: range is fairly high pitched, and it's unpleasant, especially at
Speaker 1: very high volumes. It's this piercing siren kind of sound,
Speaker 1: and if it's blasted at you loud enough, it's probably
Speaker 1: going to cause at least discomfort. And as I mentioned earlier,
Speaker 1: if the amplitude is high enough, like if you have
Speaker 1: a decibel level of around one hundred and twenty or more,
Speaker 1: and these things are capable of much more than that,
Speaker 1: then you could experience hearing loss just from relatively short
Speaker 1: exposure to these things. Of course, you could protect yourself
Speaker 1: with hearing protection, which actually works pretty darn well. That's
Speaker 1: another reason why a lot of militaries have abandoned the
Speaker 1: use of acoustic weapons, because if your enemy has ear protection,
Speaker 1: then your weapon isn't any good. It doesn't work so great.
Speaker 1: Hearing protection will reduce the decimal level enough so that
Speaker 1: it's at safe levels. It still probably won't sound great.
Speaker 1: You'll still get some of that siren noise in, but
Speaker 1: you wouldn't be in as much risk of experiencing actual
Speaker 1: hearing loss as a result of that. According to musicology
Speaker 1: now dot org, the most powerful acoustic healing devices are
Speaker 1: capable of transmitting audible sound from a distance of more
Speaker 1: than five kilometers, though most are meant for much shorter distances,
Speaker 1: like in the five hundred meter range. But don't get
Speaker 1: me wrong. Five hundred meters is still pretty darn far.
Speaker 1: I mean, that's more than five American football fields, So
Speaker 1: that's a pretty darn good distance to be able to
Speaker 1: transmit intelligible sound to a target. And as mentioned, we
Speaker 1: still don't really have a full understanding of what this
Speaker 1: effect could have on people. Jurgen Altmann research suggests that
Speaker 1: folks have made a lot of assumptions without much hard
Speaker 1: evidence to back those assumptions up. But that doesn't mean
Speaker 1: the assumptions are entirely wrong. It means that we can't
Speaker 1: be sure one way or the other without further study.
Speaker 1: And study is difficult because if the work could potentially
Speaker 1: harm your subjects, that's a huge problem. So can infra sound,
Speaker 1: you know, those very low frequency sounds below the range
Speaker 1: of human hearing. Can it at a high enough volume
Speaker 1: at enough decibels cause stuff like nausea or intestinal pain.
Speaker 1: Could it cause the dreaded brown noise, as in a
Speaker 1: sound frequency that, when played at a high enough volume,
Speaker 1: forces you to evacuate, to defecate, in other words, to
Speaker 1: poop yourself. There's no evidence of that, By the way,
Speaker 1: doesn't mean it can't happen. I just mean there's no evidence.
Speaker 1: So could it cause actual physical trauma? If you were
Speaker 1: blasting sound at like, you know, one hundred and fifty decibels,
Speaker 1: let's say it's inaudible sound. Maybe it's too low to hear.
Speaker 1: Could that very low sound at one hundred and fifty
Speaker 1: decibels cause physical harm Could it resonate with your internal
Speaker 1: organs causing them to vibrate with enough energy to hurt you.
Speaker 1: A resonance, I mean, is a thing. The classic example
Speaker 1: of resonance is you tap a crystal glass, like a
Speaker 1: champagne glass made out of crystal, and you're gonna hear
Speaker 1: it ring out a tone. Actually it rings out several tones.
Speaker 1: You get your base tone and then the harmonics of
Speaker 1: that tone, but the harmonics have less energy than your
Speaker 1: primary tone does. Anyway, if you were to play back
Speaker 1: that same base tone, that would induce the crystal champagne
Speaker 1: glass to start vibrating. It would vibrate along with this
Speaker 1: frequency you're blasting it at, if it was the resonant frequency.
Speaker 1: If it's the same frequency that generates when it when
Speaker 1: you tap it, if you blast that glass with enough
Speaker 1: volume of that tone, then it will cause the glass
Speaker 1: to deform to the point where it will shatter. So
Speaker 1: this is the class like opera singer causes glass to
Speaker 1: break using their voice trick. It's actually pretty hard to
Speaker 1: do for most singers. Usually you would need a pretty
Speaker 1: significant amount of amplification as well as incredibly good pitch
Speaker 1: to manage. It can be done, but usually it requires amplifications.
Speaker 1: It's very hard to do with your voice alone anyway.
Speaker 1: It's not just champagne flutes made of crystal that resonate.
Speaker 1: So the thought is that if you dialed an audio
Speaker 1: emitter to the right frequency, one that's low enough to
Speaker 1: penetrate the body and strong enough to really get things
Speaker 1: moving around in there, you can make a person's inerds
Speaker 1: or their air cavities inside their body vibrate. That would
Speaker 1: cause that tissue to heat up. Right. Vibration is energy,
Speaker 1: and it's like friction essentially, kind of the same way
Speaker 1: microwaves end up heating up food when you put them
Speaker 1: in the microwave, so of course that's using microwave radiation
Speaker 1: per of the electromagnetic spectrum, not acoustic waves. But I
Speaker 1: think we can all agree that having your organs all
Speaker 1: start to heat up is bad, or maybe induce air
Speaker 1: bubbles to form inside tissue that's also really bad. But
Speaker 1: as Altman points out repeatedly, there just is an evidence
Speaker 1: that this actually happens or has happened, just that there
Speaker 1: are a lot of articles that hypothesize maybe it could happen,
Speaker 1: So maybe it would, maybe it wouldn't. Finding out would
Speaker 1: require deeply unethical research and a cruel disregard for human
Speaker 1: safety or animal safety, as it turns out, and it
Speaker 1: might mean that the technology necessary to carry out such
Speaker 1: an effect would be prohibitively expensive to build and or
Speaker 1: operate if you did try to do this. So I
Speaker 1: guess that's good news. Altman's article, as I mentioned, it's
Speaker 1: free to read. I recommend going through it. It is
Speaker 1: quite long, and Alman really did his work trying to
Speaker 1: track down reputable research on the topic. The paper is
Speaker 1: longer than sixty pages, but again very easy to understand.
Speaker 1: So if you have time, check it out. That article
Speaker 1: that is really the basis for a lot of what
Speaker 1: this episode is all about, although again I went off
Speaker 1: book for the stuff that was about disrupting someone's sleep
Speaker 1: cycles or whatever. The article again, its title is Acoustic
Speaker 1: Weapons a Prospective Assessment. It's in Science and Global Security,
Speaker 1: Volume nine, two thousand and one, so check that out. Anyway,
Speaker 1: Acoustic weapons remain a thing. I still think it's really
Speaker 1: scary that we have these things that are in active
Speaker 1: use and we don't have a full understanding of the
Speaker 1: effects of that technology and how harmful they may or
Speaker 1: may not be. It may turn out that they're relatively
Speaker 1: not harmful at all, as long as your exposure to
Speaker 1: them isn't too long. But it could also turn out
Speaker 1: that they cause some pretty gnarly effects. There's the whole
Speaker 1: havana syndrome thing that I didn't get into. I'm sure
Speaker 1: the stuff they don't want you to know. Crew has
Speaker 1: done an episode on the havana syndrome. I'll have to
Speaker 1: reach out to them to make sure, but it would
Speaker 1: be weird if they hadn't. Anyway, I hope that you
Speaker 1: found this episode interesting. I hope you go check out
Speaker 1: that article. Read up on this subject, Read up on
Speaker 1: acoustic spotlights. Those things are cool. What a neat way
Speaker 1: to create this effect, Like to be able to use
Speaker 1: sound that's not in our audible spectrum to create audible
Speaker 1: sounds at a point in the distance. That's just incredible
Speaker 1: to me, Like it's phenomenal. It blows my mind. In
Speaker 1: the meantime, I hope all of you out there are
Speaker 1: doing well and I will talk to you again really soon.
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