Speaker 1: Brought to you by Toyota. Let's go places. Welcome to
Speaker 1: Forward Thinking. Hey, they're in. Welcome to Forward Thinking, the
Speaker 1: podcast that looks at the future and says, I will
Speaker 1: sit right down waiting for the gift of sound. I'm
Speaker 1: Jonathan Strickland and I'm Joe McCormick, and today we're gonna
Speaker 1: be talking about the future of sound. And there's a
Speaker 1: very good reason that we're talking about that today, which
Speaker 1: is that I've had a cold all week and I'm
Speaker 1: afraid that my voice in my mouth is going to
Speaker 1: sound bizarre. On the other end of this, I don't
Speaker 1: you know, you never really tell what you yourself sound like. People.
Speaker 1: You are sounding a little bit more of vibrato than usual, Well,
Speaker 1: that may just be my opera singing that I've been practicing.
Speaker 1: On the side, we're also recording earlier in the day
Speaker 1: than we usually do, so that could affect our sound.
Speaker 1: That is, I'm actually really surprised that I don't sound
Speaker 1: like Tom Waits right now. Usually usually before like one pm,
Speaker 1: the microphones have been drinking. Yeah, whenever, whenever I think
Speaker 1: about the future of sound, the thing that I hope
Speaker 1: that they come up with is a device that actually
Speaker 1: makes your voice sound the way it sounds in your head,
Speaker 1: so as you sounds as good as you do inside
Speaker 1: of your your head, as opposed to listening back to
Speaker 1: a recording and thinking, oh, that's not what I sound like,
Speaker 1: is it. Yeah, Today, we wanted to really look into
Speaker 1: different uses of sound. I mean, sound clearly is a
Speaker 1: very powerful thing, and in multiple ways, Like it can
Speaker 1: be figuratively powerful, like you hear something truly moving and
Speaker 1: you have an emotional response to it, or it can
Speaker 1: be physically literally powerful, like the shock way from a
Speaker 1: sonic boom, which can shatter glass or even knock you
Speaker 1: over depending upon the power of it and how close
Speaker 1: you are to the shock wave. I mean, it literally
Speaker 1: has physical power. So we're gonna really look into some
Speaker 1: cool uses for sound in the future, and we have
Speaker 1: so many of them that this is the first part
Speaker 1: of a two part episode. Thank you for pointing that out, Law,
Speaker 1: and so we don't remember halfway through and then go
Speaker 1: have to go back and say that all over. That's right,
Speaker 1: So we've got a lot to say now. The video
Speaker 1: episode that goes along with this, this pair of audio
Speaker 1: podcast I cover three interesting things about sound in the future.
Speaker 1: And we're gonna go more in depth on all of
Speaker 1: those as well as additional ones, because, as I said
Speaker 1: in the video, there's so many potential uses and things
Speaker 1: that we're learning about sound that it's really the stuff
Speaker 1: I talked about in that episodes, just the tip of
Speaker 1: the iceberg. But before we get into all of that,
Speaker 1: I think it would be beneficial for us to actually
Speaker 1: learn what sound is, how it works, because that will
Speaker 1: go on to inform, uh, the other stories we talk
Speaker 1: about and how we're making an innovative use of sound. Right, So,
Speaker 1: sound is the magic produced by the music of the
Speaker 1: sphere vibrating on the fourth harmony. You watched that April
Speaker 1: Fool's episode of for Thinking way too many times? Um, Yes,
Speaker 1: the character from that episode would certainly agree with you. However,
Speaker 1: if we want to get a little more scientific, Yeah,
Speaker 1: we're talking about sound being that's that's what's produced when stuff,
Speaker 1: when matter vibrates, all right, that's that's your basic definition.
Speaker 1: When matter vibrates, it produces sound. Whether there's anyone there
Speaker 1: to hear it, who's to say so if a tree
Speaker 1: falls in the forest, it does make a sound. You
Speaker 1: might not be there to perceive it, But it happens
Speaker 1: um So stuff vibrates at certain frequencies which are completely
Speaker 1: determined by the physical properties and the parameters of that stuff.
Speaker 1: This is called the resonant frequency, right Like how dense
Speaker 1: it is or the temperature of the of the matter
Speaker 1: can can determine it. The actual physical structure, whether it's
Speaker 1: a crystalline structure or not, that can determine it as well.
Speaker 1: If you're talking about air, like the humidity, the water content,
Speaker 1: and exactly so when we talk about the speed of sound,
Speaker 1: which will get more into in a little bit, little
Speaker 1: tiny things can make a difference. Now it might not
Speaker 1: be perceptible to we mirror mortals because we're not capable
Speaker 1: of detecting millisecond you know, differences in speed, but the altitude,
Speaker 1: the density of the air obviously would go along with that.
Speaker 1: That has an effect. The temperature, the humidity, all of
Speaker 1: these things can affect the speed of sounds. So when
Speaker 1: something vibrates like a drum, if you strike that drum,
Speaker 1: it's gonna vibrate at its resonant frequency. Same sort of
Speaker 1: thing like if you tap a glass and they hear
Speaker 1: that little tinging sound, it's going to be vibrating at
Speaker 1: that resonant frequency, and that sound will be consistent. So
Speaker 1: if you hit it again, it's going to make that
Speaker 1: same sound unless you change the parameters of that object.
Speaker 1: So like with a drum, if you were too tighten
Speaker 1: or or loosen the drumhead, you would get a different
Speaker 1: sound the next time you strike it because you've actually
Speaker 1: changed the physical parameters of that matter, or if you
Speaker 1: strike it with a different stick, different speed. Technically, the
Speaker 1: actual frequency of the sound should be more or less
Speaker 1: the same. Now, the amplitude will be different, but the
Speaker 1: frequency at which it vibrates apart from the initial contact.
Speaker 1: When the initial contact happens, you're actively introducing a bit
Speaker 1: of a random event to that matter, but it will
Speaker 1: settle into the frequency. Because it's really easy to make
Speaker 1: matter vibrate at its resonant frequency and really hard to
Speaker 1: make it vibrate at any other frequency. It's one of
Speaker 1: the things about resonance that's really interesting. Now you can
Speaker 1: do it, but it takes more effort, and as we know,
Speaker 1: based upon the laws of physics, things tend to kind
Speaker 1: of move to the easiest state. Right if it takes
Speaker 1: more energy than interpetes like no, no, no, no, no, no, no,
Speaker 1: I was kind of thinking about the difference between drumming
Speaker 1: with sticks and drumming with brushes. Sure. Yeah, Now, the
Speaker 1: actual frequencies, if you got down to a point where
Speaker 1: you were measuring the sound waves, you would see that
Speaker 1: the frequencies would be really very similar. It's just that
Speaker 1: you're generating them in a different way. So to us
Speaker 1: it sounds different, but the when you get down to
Speaker 1: like actually looking at wave forms, it would be very similar. Um.
Speaker 1: So these vibrations that we we are talking about, that's
Speaker 1: not It's not like something vibrates and then magically we
Speaker 1: can detect it. Other stuff has to happen for us
Speaker 1: to be able to perceive those vibrations. And generally what
Speaker 1: we're talking about is come pression and rare affection of
Speaker 1: air molecules. So, because as we've stated before, air is
Speaker 1: not empty, right, it is stuff, it's molecules. It's more
Speaker 1: like a soup. It's more like a soup that we
Speaker 1: just hang out in all the time. Yeah, it obeys
Speaker 1: the laws of fluid dynamics. Delicious nitrogen soup. Yeah. If
Speaker 1: there weren't that stuff, we would be in a vacuum
Speaker 1: and wouldn't be talking right now, because we'd be unable
Speaker 1: to generate sound or breathe. But you know sound on
Speaker 1: the same principle you've heard behind when you hear a
Speaker 1: nerd get mad that while in this movie something blew
Speaker 1: up in space and you heard it and you're not
Speaker 1: You really shouldn't be able to hear it. Yeah, if
Speaker 1: you were in the spacecraft, you would probably hear something.
Speaker 1: For all the air escaped. Every spaceship is miked extensively. Yeah,
Speaker 1: maybe it's and that's what the filmmakers are using. Yeah,
Speaker 1: it's just that whatever whatever space camera is on, that
Speaker 1: just automatically adds in the sound of an explosion, because
Speaker 1: otherwise is are a little tiny human brains would crack. Um.
Speaker 1: So when when the vibrations are moving, that causes the
Speaker 1: air molecules to move in this process of compression and rarefaction.
Speaker 1: That's essentially when air molecules are pressing together and then
Speaker 1: spreading apart again. Now that causes the adjacent air molecules
Speaker 1: to move, and so on and so forth until you
Speaker 1: go from the source of the sound to an ear drum.
Speaker 1: So when we're talking about the perception of sound, which
Speaker 1: from us, for we humans tends to be through hearing,
Speaker 1: but you can actually receive sound also through you know,
Speaker 1: you could have a tactile sensation, you could feel sound.
Speaker 1: But when we're talking about hearing, those air molecules end
Speaker 1: up impacting our ear drums. Now, our ear drums are
Speaker 1: really important. And it's a membrane that's attached to a
Speaker 1: series of three small bones that are in our middle
Speaker 1: ear that act as an amplifier. So your ear drums
Speaker 1: starts to vibrate, these three small bones essentially amplify that
Speaker 1: and they end up transmitting those vibrations to are to
Speaker 1: the cochlea which has this fluid in it and little
Speaker 1: tiny read like uh fibers, I guess you could say. Yeah.
Speaker 1: And those hair quot marks in the air, they're we're
Speaker 1: really useful on audio. And those hairs have specific resonant frequencies.
Speaker 1: So certain hairs will start to vibrate depending upon the
Speaker 1: motion of the fluid, and other other hairs won't vibrate
Speaker 1: because the resonance won't match up, you know, the rather,
Speaker 1: the vibrations won't match up with their particular resonance, right,
Speaker 1: And so the the hairs when they vibrate will send
Speaker 1: a signal like like pop off a little neuron to
Speaker 1: your brain saying like, hey, this hair vibrated, and your
Speaker 1: brain amasses all of those signals from those hairs to say, oh,
Speaker 1: this is what this thing sounds like. Right, So the
Speaker 1: sound you are hearing right now as you listen to
Speaker 1: this podcast is actually your brain interpreting those little vibrations
Speaker 1: of reads and then sending little electrical impulses and then
Speaker 1: there you go. So it's kind of cool and weird
Speaker 1: also in a way to think like, oh, sound is
Speaker 1: something that largely is happening inside my head. Like I
Speaker 1: know that there actually is a physical manifestation of sound
Speaker 1: because we have but but but ultimately our perception is
Speaker 1: all in the head. It's not like if you take
Speaker 1: the brain out that, uh you know, what would that
Speaker 1: sound be like without that particular process. Who can say
Speaker 1: that's not how we are, Like all reality is like
Speaker 1: a dream man. Yeah, Yeah, that's toads where I was
Speaker 1: going with that. So when we talk about about actually
Speaker 1: measuring sound, there are three things we typically look at,
Speaker 1: which are the frequency of the sound, the amplitude of
Speaker 1: that sound, and the wavelength of the sound wave. Yeah,
Speaker 1: and one thing that makes this kind of difficult with
Speaker 1: sound is that you usually picture these three variables in
Speaker 1: terms of a transverse wave like light or like the
Speaker 1: waves in the ocean shan, where the oscillation of the
Speaker 1: wave is moving perpendicular to the motion of the wave.
Speaker 1: So like you've often seen a picture of a wave,
Speaker 1: it's little hoops going up and down along a central midpoint,
Speaker 1: and sound is sort of the exception to that type
Speaker 1: of wave of motion. It's not really like that. It's
Speaker 1: a compression wave. It radiates outward from the source of
Speaker 1: the sound as well, so the oscillation is going parallel
Speaker 1: to the direction of the way right, and it's three dimensional,
Speaker 1: But we do use that two dimensional representation of waves
Speaker 1: to to look at sound waves because tiny delicate human brains. Yeah,
Speaker 1: it's way easier, it's useful. Yeah, it ends up being
Speaker 1: a useful way to describe the behavior of the sound waves.
Speaker 1: And it's not that the like technically you could say
Speaker 1: the depiction is not truly correct in the sense of
Speaker 1: the way the waves behave, but it ends up being
Speaker 1: useful for talking about things like um in versus, like
Speaker 1: an inverted sound wave, and uh, you know, when you
Speaker 1: pair it with the original sound wave what happens. Uh. So,
Speaker 1: frequency is what we would normally associate with pitch, right, technically,
Speaker 1: I mean it's it's this is the easiest way of
Speaker 1: saying it. The higher the frequency, the higher the pitch. Now,
Speaker 1: human hearing has a range of frequencies that typically we
Speaker 1: can detect. Now, this is typical in the sense that
Speaker 1: there are people who have a hearing range that can
Speaker 1: go a little further outside of it, and there's some
Speaker 1: people who it's narrower and um, typically we talk about
Speaker 1: it being from twenty hurts, which is twenty cycles per second.
Speaker 1: So that would be the frequency of you know, when
Speaker 1: these waves would pass. Uh, twenty of those cycles in
Speaker 1: the second would be one hurt or twenty hurts rather
Speaker 1: or up to twenty killer hurts, which is twenty thousand
Speaker 1: cycles per second. Uh. Again, that's a general rule of thumb.
Speaker 1: Some humans can hear outside of those ranges, and some
Speaker 1: are are are limited to a much narrower range. And
Speaker 1: and really the range that we hear best in is
Speaker 1: one killer hurts to about four killer hurts. Yeah, that
Speaker 1: that tends to be the range we mostly encounter. And
Speaker 1: are you know, like the range of human voices. It's
Speaker 1: what we work in daily. Yeah, what is the singular
Speaker 1: of killer hurts. It wouldn't be kill a hurt It's
Speaker 1: it's still hurt hurts because hurts is named after Hurts
Speaker 1: named after a person. But you don't say hurts is right, Yeah,
Speaker 1: it's it's four killer hurts is. It's like, dear, I'm
Speaker 1: going to start saying that from now on, you're being
Speaker 1: kill a hurtful all right? Anyway, moving on, always say
Speaker 1: it at one hurts all right. Now, obviously, you can
Speaker 1: have frequencies outside the range of human hearing, and these
Speaker 1: frequencies can still have a physical effect, and we will
Speaker 1: talk about any of those when we get into the
Speaker 1: future uses of sound. Yeah. In fact, a lot of
Speaker 1: times we specifically want to use frequencies of sound outside
Speaker 1: the range of human hearing. Yeah, because if you're using
Speaker 1: it within the range of human hearing, it could be
Speaker 1: really irritating depending upon the application. Right. Uh So, next
Speaker 1: we have the amplitude. So if you picture the transverse wave,
Speaker 1: right we were talking about, that's going to be the
Speaker 1: distance between the midpoint and the crest or the trough
Speaker 1: of the wave, and uh, amplitude essentially ends up being
Speaker 1: perceived as volume. So the greater the amplitude, the louder
Speaker 1: the sound. So your your frequency determines the pitch, the
Speaker 1: amplitude determines the volume. Then you have wavelength. This is
Speaker 1: the distance between two analogous points on two successive waves.
Speaker 1: So you pick a point on one wave, you pick
Speaker 1: essentially the same point on the next wave, and you
Speaker 1: measure the distance between the two. That is the wavelength
Speaker 1: of the sound wave. Very often you could just say
Speaker 1: it's crest to crest, right. So this depends upon the
Speaker 1: frequency and the medium through which the sound is traveling.
Speaker 1: Wavelength can vary even within the air, again, depending upon
Speaker 1: that temperature of the air or the humidity or the
Speaker 1: density of the air. Um and wavelength of frequency are
Speaker 1: inversely proportional to one another, So if the wavelength of
Speaker 1: a sound wave increases in uniform medium, the frequency decreases.
Speaker 1: So uh, this is important when you're starting to figure
Speaker 1: out things like the speed of sound through any given medium.
Speaker 1: If you know the frequency and you know the wavelength,
Speaker 1: then you multiply the two together and you get the
Speaker 1: speed of sound. And it also comes into effect when
Speaker 1: we're studying things like the Doppler effect, where the extension
Speaker 1: or the compression of waves can affect the frequency right. Uh. Now,
Speaker 1: we also need to talk about how sound waves can
Speaker 1: interact with each other because they could do some pretty
Speaker 1: interesting things. If you get two identical sound waves played together,
Speaker 1: they can amplify one another, so their amplitude can be
Speaker 1: uh additive. If you end up getting a sound wave
Speaker 1: where it encounters its inverse, they cancel each other out.
Speaker 1: This is the way noise canceling headphones work. They attempt
Speaker 1: to create an inverse wave that would end up canceling
Speaker 1: out all the noise that's around you, creating like a
Speaker 1: little pocket of of dead sound air. Yeah, that's the
Speaker 1: goal if they if they are working properly, Um, you
Speaker 1: know your your mileage may vary depending upon the sound
Speaker 1: canceling headphones. Uh. And two different sound waves that mixed
Speaker 1: together end up creating like if you were to look
Speaker 1: at this this depiction of a sound wave, it would
Speaker 1: end up looking really super funky because the the the
Speaker 1: troughs and crests would be affected by each other and
Speaker 1: you would end up getting a result where if one
Speaker 1: had a bit of a crest but the other one
Speaker 1: had a deeper trough, then it's gonna look like, well,
Speaker 1: now the new sound wave has a trough, but it's
Speaker 1: not as deep as from two. Very complex and mathematical
Speaker 1: and and actually I would totally love to have like
Speaker 1: a like a sound engineer come on the show and
Speaker 1: talk about it, because it is whoa like like way.
Speaker 1: Every time I start thinking about it, my brain just
Speaker 1: kind of goes It's it's also way easier to explain
Speaker 1: if you have the the visual aids of nearby, and
Speaker 1: then we do not obviously as an audio podcast. So
Speaker 1: and it's kind of funny that you need visual aids
Speaker 1: to explain sound that that is a rather amusing a
Speaker 1: little I mean, it's I guess it's a less more
Speaker 1: set version of ironic, don't you think. One more interesting
Speaker 1: things sound waves can do when interacting with each other is,
Speaker 1: for example, if you create an interference pattern with the
Speaker 1: sound wave and its reflection of itself off of a
Speaker 1: hard surface, you can create a standing wave sound. And
Speaker 1: we'll talk about those in a bit too. Yeah, that
Speaker 1: they come into use in some of the technology, but
Speaker 1: standing waves are a fascinating thing that can happen with
Speaker 1: all kinds of wave phenomena in nature, which is Yeah,
Speaker 1: one of those things that that or might seem counterintuitive
Speaker 1: at first when you think about like, well, how could
Speaker 1: how could sound do this thing? But as you learn
Speaker 1: more and more health sound works, it starts to make sense.
Speaker 1: It's just based upon what what we can directly observe
Speaker 1: in our day to day lives. It seems really like, wow,
Speaker 1: that's magic. Yeah, yeah, although it's not. I mean at
Speaker 1: a at a more macro level, we've all experienced a
Speaker 1: sonic boom, right, and and so we have some kind
Speaker 1: of experience with what sound is this physical force? Right
Speaker 1: that shows that this isn't just all in your head.
Speaker 1: Even though the perception of sound maybe in your head,
Speaker 1: there's the you can physically feel sound like from a
Speaker 1: sonic boom. You can feel that shock wave hit um
Speaker 1: and uh. You know this is something where it's that
Speaker 1: compression and rare affaction. You can't get that wave coming
Speaker 1: out from a big event like a sonic boom. It
Speaker 1: can do some damage, like remember when the meteorite passed
Speaker 1: overhead of in various aerias in Rush, where there were
Speaker 1: towns that were reporting that there were entire buildings that
Speaker 1: add a face of the wall, all the glass just
Speaker 1: shattering because that that pressure wave was so powerful. So
Speaker 1: sound is definitely something that can have a big impact,
Speaker 1: literally a big impact. Now, we talked a little bit
Speaker 1: about the speed of sound. That sound travels at a
Speaker 1: uniform speed depending upon the medium through which it travels.
Speaker 1: So if you want sound to travel faster or slower,
Speaker 1: really all you can do is affect the medium. You
Speaker 1: can either transition it from one medium to another, or
Speaker 1: you affect that those physical parameters of the medium. You
Speaker 1: can't do it by increasing the frequency or the wavelength
Speaker 1: because if you if you make the frequency, if you
Speaker 1: increase the frequency, the wavelength will decrease because they're inversely proportional.
Speaker 1: If you increase the wavelength, then the frequency will decrease
Speaker 1: again inversely proportional. So the only way you can make
Speaker 1: the sound travel at a different speed, because remember that's
Speaker 1: the product of wavelength and frequency, The only way you
Speaker 1: can make the sound travel at a different speed is
Speaker 1: to change the medium in some way. So that's kind
Speaker 1: of interesting too. Now that might mean transferring it from
Speaker 1: one medium to another, like a solid to a gas,
Speaker 1: or one liquid to another liquid, or anything along those lines,
Speaker 1: or it might mean that you physically change the medium
Speaker 1: in some way, um you create you know, like if
Speaker 1: you increase the tension on a drumhead, technically you're stretching
Speaker 1: everything out. That changes the nature of that matter. So, uh,
Speaker 1: that is important to remember as well, because knowing that
Speaker 1: the sound of the speed of sound is going to
Speaker 1: be constant gives us lots of opportunities to use sound
Speaker 1: in super cool ways. Right Yeah, what once you once
Speaker 1: you batten down a single variable in a scientific experiment,
Speaker 1: of course, that gives you a lot of opportunity to
Speaker 1: play with the others, right, right. So one of the
Speaker 1: ways that people are going to be most familiar with
Speaker 1: using sound as a sort of like novel technological tool
Speaker 1: will be in medicine. Yes, I mean many people have
Speaker 1: themselves undergone an ultrasound right yeah, yeah, it's pretty common. Yeah,
Speaker 1: it's very common. So you can have like ultrasound imaging
Speaker 1: as a way of like getting a look at what's
Speaker 1: inside your body. A lot of times this will be
Speaker 1: done during a pregnancy or to try to diagnose you know,
Speaker 1: gall bladder stones or any kind of thing like that,
Speaker 1: or you could use it as a tool, say to
Speaker 1: for example, dissolve kidney stones. But there are lots of
Speaker 1: new ways that people might be using ultrasound in medicine,
Speaker 1: for example, even in diagnosing cancer. Yeah, and actually ultrasound
Speaker 1: is currently being used in diagnosing cancer. I'm going to
Speaker 1: talk about a super fancy sound method in a minute,
Speaker 1: but let's let's talk about this ultrasound specifically as it
Speaker 1: relates to cancer, because it is so fascinating to me. Okay,
Speaker 1: So various imaging method these days are used to screen
Speaker 1: for tumors within a patient's body, And it's pretty cool
Speaker 1: that we have imaging methods because, uh, they're really good
Speaker 1: at detecting cancer in its early stages before it's done
Speaker 1: too much damage. They're all pretty new. Like previous to
Speaker 1: the late nineteen sixties, tumors were basically discovered by either
Speaker 1: looking at them or poking them, and that's almost the
Speaker 1: technical term really, or just like waiting until the patient
Speaker 1: symptoms developed to the point that a doctor thought it
Speaker 1: was worthwhile to cut them open and see what was
Speaker 1: going on. And that's the other way in which imaging
Speaker 1: is cool, of course, as a screening method, because most
Speaker 1: forms of it are pretty safe and non invasive. From
Speaker 1: the nineteen twenties to the nineteen sixties, a few tests
Speaker 1: were developed that could detect cancerous or pre cancerous cells
Speaker 1: from like membrane swabs or urine or fecal matter, but
Speaker 1: it wasn't until the late nineteen sixties that researchers developed mammography,
Speaker 1: which of course is a specialized X ray method for
Speaker 1: viewing breast tissue that became the first widely used imaging
Speaker 1: method for cancer. But in the early nineteen eighties, researchers
Speaker 1: began developing other imaging methods, starting with ultrasound. Uh yeah,
Speaker 1: so it was first used in the detection of prostate cancer,
Speaker 1: though it's since been found to be no more accurate
Speaker 1: than a classic touch based digital examination from a trained doctor,
Speaker 1: and these days, ultrasound is mostly used in combination with
Speaker 1: other tests like like mammograms or blood tests or biopsies,
Speaker 1: in patients that have particularly high risks of developing cancer,
Speaker 1: or when other methods wouldn't be as effective due to
Speaker 1: some other physical factor about the patient's body, or when
Speaker 1: doctors aren't sure whether a lump is assist or tumor
Speaker 1: and they don't want to jump straight to biopsy. And
Speaker 1: what you may be asking is how can as ultrasound
Speaker 1: possibly tell the difference between assistant a tumor, and that
Speaker 1: is going back to the speed of sound. Assist is
Speaker 1: liquid filled, so a sound wave will bounce off it,
Speaker 1: or sound wave will interact with it differently than it
Speaker 1: will with a solid tumor. So let's talk a little
Speaker 1: bit about how this this actually works in your body.
Speaker 1: It's considered really safe. You know, it's just sound waves,
Speaker 1: so there's an extremely low risk of any harmful side effects,
Speaker 1: and it's super cheap compared to like computerist tomography or
Speaker 1: m r I. It's not as detailed, I mean, and
Speaker 1: the downsides of ultrasound used in medical applications is that
Speaker 1: it's it's hard to get good images through a lot
Speaker 1: of fat tissue, and it's impossible to get images through
Speaker 1: uh like air filled lungs or dense bones or anything
Speaker 1: like that. So ultrasonic waves are are really high frequency
Speaker 1: sound waves. And therefore ultrasound is a form of scenography
Speaker 1: that that uses these things that are that are just
Speaker 1: way above the human hearing level, like like one to
Speaker 1: one point five mega hurts hurts millions of cycles per second,
Speaker 1: right right, um, And I mean y'all know how how
Speaker 1: sonar works, Yeah, You've got a transmitter and receiver that
Speaker 1: sends out a sound wave, receives echoes of that wave
Speaker 1: once it's bounced off of an object, and then determines
Speaker 1: how far away the object is based on the time
Speaker 1: it took for the echo to return, uh, and the
Speaker 1: speed of sound through the medium in question, air, water,
Speaker 1: or your body, or et cetera. UM. So ultrasonography is
Speaker 1: is sonar just turned up to eleven? Uh? You can?
Speaker 1: You can? You can use what's called a transducer probe.
Speaker 1: And and and that's the that's the kind of stick or
Speaker 1: like mouse looking thing that you might have seen or
Speaker 1: or had used on on you during an ultrasound um
Speaker 1: and and it can send out millions of ultrasonic pulses
Speaker 1: every second the sound waves bounce off of the different
Speaker 1: kinds of tissue in the patient's body and back to
Speaker 1: the probe. And the probe is sensitive enough and the
Speaker 1: computer it's attached to is clever enough that it can
Speaker 1: track and collect those millions of signals and turn them
Speaker 1: into a real time image of the surfaces that the
Speaker 1: waves are reflecting off of. Because we can track the
Speaker 1: time the waves took to get back, and we know
Speaker 1: how fast. The waves travel through different tissues muscle, bone
Speaker 1: and fat and tumors and etcetera, So a tumor will
Speaker 1: look different than the surrounding tissue. Interesting also, you know,
Speaker 1: And just to to kind of add to that, not
Speaker 1: for ultra sound, but for sonar. One of the other
Speaker 1: cool things is what we mentioned earlier, what Joe mentioned
Speaker 1: about about the Doppler effect. You can even with sonar,
Speaker 1: tell if something is moving towards you or moving away
Speaker 1: from you based upon the nature of the sound wave
Speaker 1: that echoes back. Again, not really relevant and ultrasound, but
Speaker 1: one of those things that one of the other main
Speaker 1: uses of sound. Not just by us either. There are
Speaker 1: a lot of creatures that use ultrasound like echolocation. So
Speaker 1: all of this is really cool, But the biggest danger
Speaker 1: of cancer isn't from a single tumor itself, but from metastasis.
Speaker 1: That's when cancer spreads from one tumor site to somewhere
Speaker 1: else in the body. And the way that this happens
Speaker 1: is when cells or very small clusters of cells break
Speaker 1: off from a tumor and get into the bloodstream or
Speaker 1: the lymph system and travel to another part of the
Speaker 1: body and begin multiplying there or or spurring abnormal growth annunciation, yes,
Speaker 1: sound waves. So these these cells are called circulating tumor
Speaker 1: cells or CTCs, and they cannot be detected by ultrasound
Speaker 1: or even the more sensitive imaging methods like m r
Speaker 1: I or CT scans. Now, these cells were first hypothesized
Speaker 1: all the way back in nine but their exact capacity
Speaker 1: and really the entire process of metastasis has been a
Speaker 1: subject of study and debate ever since then. The current
Speaker 1: popular theory says that CTCs are basically cancer stem cells,
Speaker 1: which I mean, I mean, it's really it's really fascinating.
Speaker 1: It's it's one of those things that I get so
Speaker 1: excited about and then feel really bad about being so
Speaker 1: excited about. I feel like, I feel like Egon, You're
Speaker 1: like Ian Holme and Alien. I admire its purity exactly.
Speaker 1: Um So, despite the fact that we don't really know
Speaker 1: what's going on with ctc s, it's pretty safe to
Speaker 1: say that it would be cool to be able to
Speaker 1: detect them in the blood stream of a patient with
Speaker 1: a tumor in order to inform advice on further treatment
Speaker 1: of that tumor and to recommend future screenings. But they
Speaker 1: are really hard to find. You can only expect to
Speaker 1: find like one ctc per billion blood cells and a sample,
Speaker 1: and you said that we can't currently find these with
Speaker 1: ultrasound or any other imaging method that is correct. The
Speaker 1: ways that we currently have to detect them um usually
Speaker 1: either will damage the CTC, which sucks because then you
Speaker 1: can't study it further, or just just they're not very effective.
Speaker 1: And we do have some acoustic separation methods for getting
Speaker 1: CTCs out of a blood sample, but they've satically fallen
Speaker 1: into that latter category that the technology just hasn't been
Speaker 1: good enough. The devices used have been slow and awkward
Speaker 1: and kind of finicky, but acoustic methods don't harm or
Speaker 1: mark or otherwise mess with the cells, so science has
Speaker 1: been working on it. Yeah, this is a pretty exciting stuff.
Speaker 1: I read this story and originally I was gonna say
Speaker 1: researchers from but then I looked at all the different
Speaker 1: groups and there's like six different universities that are all
Speaker 1: associated with the study. Yeah, I think it was all
Speaker 1: being headed out of a single university and I did
Speaker 1: not write it down in the notes. That is a
Speaker 1: really good tangent um. But but yeah, the fascinating part
Speaker 1: about the study is that it's it's so interdisciplinary. Yah,
Speaker 1: it's a combination of cancer research and uh, device creation
Speaker 1: and microchips and sound waves. Yeah, you've got engineers, you've
Speaker 1: got oncologists, you've got all sorts of experts in various
Speaker 1: fields that all have worked together on this, and uh,
Speaker 1: it's a little and it's one of those things I say,
Speaker 1: it's a little complicated, which mostly means that's code for
Speaker 1: Jonathan sort of but maybe not really understands how this works.
Speaker 1: But it does come back to that idea that sound
Speaker 1: has a physical like exertion, like it can push. Um. So, first,
Speaker 1: what you have to imagine is a micro fluid I channel,
Speaker 1: so a very narrow channel. Yeah, this is a device
Speaker 1: that's maybe about the size of a quarter or so,
Speaker 1: like maybe like a half dollar. Yeah. Now it has transducers,
Speaker 1: which are the things that can convert electricity to sound,
Speaker 1: all right, So they are used as essentially ultrasonic emitters,
Speaker 1: and the transducers collectively produce what what was called in
Speaker 1: the study a tilted angle standing surface sound wave, or
Speaker 1: actually a collection of them sound waves, I should say. Uh,
Speaker 1: so these are waves that contain points that were called
Speaker 1: nodes that stands still relative to the rest of the wave.
Speaker 1: So you get your your blood sample flowing through this
Speaker 1: micro fluid channel with the transducers. Uh, they encounter these
Speaker 1: nodes and anti noodes that exert force through this acoustic pressure,
Speaker 1: and the pressure ends up pushing the different cells in
Speaker 1: different trajectories. So the CTCs get pushed off in one
Speaker 1: trajectory and the blood cells into a different trajectory. Uh.
Speaker 1: And this continues down the channel, so successive transducers add
Speaker 1: to that effect. So the initial change in trajectory is
Speaker 1: so small that it would be difficult to detect. But
Speaker 1: because this is happening again and again through this very
Speaker 1: tiny channel, Yeah, you get this this like microsecond of
Speaker 1: of sound pushing at something. And eventually, with enough of
Speaker 1: those little pushes down the channel, the the different types
Speaker 1: of cells will separate themselves out right. So that way
Speaker 1: you end up having your blood cells and your CTCs. Uh.
Speaker 1: And you can actually then really study the CTC and
Speaker 1: they haven't been damaged, right right. Yeah, they're ultrasonic waves,
Speaker 1: so they don't damage tissue as we talked about earlier,
Speaker 1: and and you can tune the wavelengths to cur to
Speaker 1: correspond to the size and weight of particular particles. Uh.
Speaker 1: The these these cancer cells are generally a little bit
Speaker 1: larger and heavier than red blood cells. Certainly maybe along
Speaker 1: the along the same size lines of white blood cells.
Speaker 1: But yeah, what once you once you've sorted them out, Oh,
Speaker 1: it's so cool. Yeah, And what I thought was amazing
Speaker 1: about this approach was that you can tune those transducers.
Speaker 1: You could develop transducers for specific types of CTCs, right,
Speaker 1: and that would make them very efficient. However, they discovered
Speaker 1: that even if you didn't tune them, they were efficient enough,
Speaker 1: so that was still an incredible gain over other methods.
Speaker 1: They found that they could capture eight three per cent
Speaker 1: of the CTCs within a sample, even if the trend
Speaker 1: inducers were not tuned to that specific type of CTC. Yeah,
Speaker 1: they optimized the device for a couple types of cancer
Speaker 1: cells HeLa cells and MCF seven cells, and those two
Speaker 1: are both pretty similar in size. But then they ran
Speaker 1: the experiment with other types of cancer cells and it
Speaker 1: worked just as well. Uh. They're calling this method acoustic tweezers,
Speaker 1: and the team is looking now into how to make
Speaker 1: these devices disposable because you're dealing with patient blood samples
Speaker 1: so disposable, mass producible, and keeping the costs down because
Speaker 1: right now it's a pretty cheap technology. Yeah, so this
Speaker 1: could be a really huge benefit for uh, for for
Speaker 1: doctors who are who need to do something like a
Speaker 1: liquid biopsy on a patient. Well, that's amazing. But of
Speaker 1: course that's not the only way that science is pushing
Speaker 1: the boundaries of our uses of ultrasound into strange new territory.
Speaker 1: And I love the us the word pushed. Yeah. Yeah, Well,
Speaker 1: tweezing the boundaries has tweez a verb, yese, tweezing the
Speaker 1: boundaries of medical science and ultrasound. Because here's something interesting
Speaker 1: I came across a while back when I was writing
Speaker 1: about brain to brain communication. We've talked before on the
Speaker 1: podcast about transcranial direct current stimulation and transcranial magnetic stimulation.
Speaker 1: They're these strange methods science have figured out may be
Speaker 1: able to affect the brain. I think the jury is
Speaker 1: still out in a lot of ways on like what
Speaker 1: exactly the effect is and how useful it is. But
Speaker 1: they're using electricity or strong magnet electromagnetic forces to cause
Speaker 1: stimulation in certain like targeted regions of the brain to
Speaker 1: hopefully produce a desired effect in an experiment and without
Speaker 1: the need for invasive surgery. That's the transcranial part. Yeah,
Speaker 1: so you don't have to open person up and put
Speaker 1: electrodes inside the parts of their brain that you want
Speaker 1: to mess with. Yeah. We talked about this about how
Speaker 1: some people were doing it to themselves with small like
Speaker 1: electrodes attached to their temple. And we're not recommended to
Speaker 1: try this at home, folks, but yes, some people out
Speaker 1: there do think it makes them smarter if they hook
Speaker 1: a nine volt battery up to their scalp. It's odd
Speaker 1: I feel smarter about not detching ninevola um. But there's
Speaker 1: another method actually is out there for non invasive brain stimulation,
Speaker 1: and instead of being based on electricity or electromagnetism, this
Speaker 1: is based on ultrasounds. It's known as transcranial focused ultrasound. Right.
Speaker 1: H There was a paper that was published in and
Speaker 1: Nature Neuroscience that was all about experimentation in this research
Speaker 1: into this field of using ultrasonic frequencies. So very similar
Speaker 1: in in many ways to the methods that Joe was
Speaker 1: just talking about, except instead of using magnetic fours or electricity.
Speaker 1: You're using very focused beams of ultrasonic frequencies aimed at
Speaker 1: particular areas of the brain, and it turns out it
Speaker 1: does seem to have an effect. The paper specifically talked
Speaker 1: about the research that went into using this focused ultrasound
Speaker 1: on the so much somata sensory cortex. So essentially they
Speaker 1: the area where we have our our our senses, you
Speaker 1: know that that part of our brain. That's that's uh. Particularly,
Speaker 1: they were targeting tactile uh census, so our sense of touch.
Speaker 1: So here's what was going on in the actual research.
Speaker 1: They focused beams of sound waves at five killer hurts,
Speaker 1: so well above that twenty killer hurts range of human
Speaker 1: hearing and for the record, well above the hearing range
Speaker 1: of basically any animal. Yeah. Uh, So they targeted this
Speaker 1: through the skull at that cortex, and they saw that
Speaker 1: there did seem to be some effect of the quote
Speaker 1: modulation of the firing of neurons end quote. So how
Speaker 1: how was that a thing? This is where science looks
Speaker 1: at us and just goes there's an effect, but the
Speaker 1: actual mechanism of the effect is not understood at this time.
Speaker 1: There are some hypotheses about what's going on. But there's
Speaker 1: not you know, there's not a oh it does this
Speaker 1: because of this? So what are some of those hypotheses.
Speaker 1: This is the one that was in the paper, which
Speaker 1: I love. So it says the pulse acoustic pressure wave
Speaker 1: may locally shift the balance of excitation and inhibition by
Speaker 1: acting on mechanically sensitive components of the brain, including cell membranes,
Speaker 1: ion channels, and synaptic vesicle cycles. So, in other words,
Speaker 1: if I can paraphrase, it's affecting the modulation of neuronal
Speaker 1: activity by poking stuff with sound. So it sounded like
Speaker 1: to me the method of poking your brain without cutting
Speaker 1: your skull open, right right, It's that same pushing effect
Speaker 1: that we were talking about with the cancer cells, right yeah.
Speaker 1: So so it's just just really localized. I like to
Speaker 1: think of it as like, because I'm from the Deep South,
Speaker 1: I like to think of it as a bunch of
Speaker 1: guys just standing around with a little sound emitter saying, hey,
Speaker 1: y'all watch this. Now. Clearly that is not what happened,
Speaker 1: But I thought you were going to say it's like
Speaker 1: a bunch of guys standing around a possum and a
Speaker 1: ditch poking it with the stick. Well, you know, we're
Speaker 1: my my my chart of the evolution of man kind
Speaker 1: of resembles what you're talking about right there. It's we
Speaker 1: don't know that. These scientists involved didn't sit there going like,
Speaker 1: hey guys, so now we can say allegedly because we're alleged, No, no,
Speaker 1: we're not. But potentially this could mean, let's all right,
Speaker 1: the mechanisms aside, we don't understand the mechanisms fully yet
Speaker 1: or really we just had some vague ideas of what's
Speaker 1: going on. But that aside, ultrasonic stimulation might be able
Speaker 1: to offer neuroscientists a more precise tool for neuronal stimulation,
Speaker 1: in other words, using magnets, using electricity. It can be
Speaker 1: you know, you're you're kind of aiming in the general
Speaker 1: direction of the area you wish to affect, knowing that
Speaker 1: you're also probably going to affect some surrounding areas, right
Speaker 1: That might have consequences, and it may have it may
Speaker 1: end up affecting the outcome of your research without you
Speaker 1: being able to, you know, use a full level of
Speaker 1: confidence about what's actually happening. This would allow perhaps a
Speaker 1: greater level of precision. Uh still not you know, pinpoint precision.
Speaker 1: We're talking about the area that would be about the
Speaker 1: size of the tip of your little fingers. So not
Speaker 1: like you couldn't target specifics neurons, you could target clusters. UH.
Speaker 1: But it also could be h method of safely testing
Speaker 1: this because again we don't have to worry about causing
Speaker 1: tissue damage uh. And the research itself, they looked at
Speaker 1: how this actually did allow the people undergoing the tests
Speaker 1: to have a better ability to detect subtle differences in
Speaker 1: tactile sensations. So imagine that you have two different things
Speaker 1: that come into contact with your skin, and perhaps the
Speaker 1: difference between the two are there there. You know, from
Speaker 1: from a tactile sensation standpoint, they are not that different
Speaker 1: from one another. They discovered that using this ultrasonic stimulation,
Speaker 1: people who the people who did have that we're better
Speaker 1: able to tell the differences between the different tactiles stimulations
Speaker 1: than was who did not. So they had an increased
Speaker 1: facility from their sense of touch, which means that you
Speaker 1: might be able to through this modulation do lots of
Speaker 1: different things, including you could potentially address various disorders, could
Speaker 1: be part of physical therapy YEP. It might even eventually
Speaker 1: become something similar to what we've seen with the transcranial stimulation,
Speaker 1: like the direct current stimulation. The idea of being able
Speaker 1: to boost things like a learning ability that, of course
Speaker 1: is so far off into the future though, that's way
Speaker 1: trickier than than touch. Yeah, we're we're we're talking about
Speaker 1: there's potential, but that potential may never be realized. Yeah.
Speaker 1: I wouldn't describe it in terms of time. I don't
Speaker 1: know IF's necessarily so far off. I describe it in
Speaker 1: terms of uncertainty, like we don't really know, I mean,
Speaker 1: far off from a sense of what we are capable
Speaker 1: of knowing right now, as opposed to I mean it
Speaker 1: may turn out like sometimes science comes up with things
Speaker 1: where we don't fully understand the way it's working, but
Speaker 1: we have a practical effect, so we go with it.
Speaker 1: Sometimes that turns out. That'd be great. I feel I
Speaker 1: should just have like a song version of twenty to
Speaker 1: forty years that I just like to play a little,
Speaker 1: a little jingle, yeah and now forty years by Noel Brown.
Speaker 1: This is the point in our notes where we had
Speaker 1: decided that we were going to split the episode and
Speaker 1: pick up again in another episode, because we just got
Speaker 1: so much to talk about with sound, and obviously, you know,
Speaker 1: we had to lay the groundwork and ultrasonic frequencies was
Speaker 1: that was a great way to get started. And in fact,
Speaker 1: we'll pick up with a different application of ultrasonic frequencies
Speaker 1: that has nothing to do with the field of medicine. Ah. Yeah,
Speaker 1: we're over talking about the gross spot stuff that we
Speaker 1: have been talking about all episod. Yeah, so we're gonna
Speaker 1: have some non gross, non body stuff and maybe some
Speaker 1: gross stuff that has nothing to do with bodies in
Speaker 1: our next episode. You'll have to tune in and find out. Meanwhile,
Speaker 1: if you have any suggestions for future episodes, uh, you
Speaker 1: should definitely get in touch with us. Let's know what
Speaker 1: you think. The email address you can send that to
Speaker 1: is f W Thinking at health stuff Works dot com.
Speaker 1: Or you can drop us a line on Twitter or
Speaker 1: Google Plus or Facebook. At Twitter and Google Plus, we
Speaker 1: are f W Thinking, search FW Thinking and Facebook. It'll
Speaker 1: pop right up. You can leave us a message. We've
Speaker 1: been getting some great requests and some notes from you
Speaker 1: guys that we really do love. We read all of them,
Speaker 1: So keep an ear out because we're going to have
Speaker 1: some listener request episodes coming up very soon, and yours
Speaker 1: could be the next one. Just send us that message
Speaker 1: and we will talk to you again about sound really soon.
Speaker 1: For more on this stuffic in the future of technology,
Speaker 1: visit forward Thinking dot Com, brought to you by Toyota.
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