The patient's age and sex did not permit me to resort to the kind of examination I have just described, I e. Direct application of the ear to the chest. I recalled a well known acoustic phenomenon. If you place your ear against one end of a wood beam, the scratch of a pin at the other end is distinctly audible. It occurred to me that this physical property might serve a useful purpose in the case I was dealing with.
I then tightly rolled a sheet of paper, one end of which I placed over the precordium and my ear to the other. I was surprised and elated to be able to hear the beating of her heart with far greater clearness than I ever had with direct application of my ear. I immediately saw that this might become an indispensable method for studying not only the beating of the heart, but all movements able of producing sound in the chest cavity.
I was so excited for this episode.
Are me too? Me too? I have listened to more hearts, I think, than I ever have in lung sounds. We were just listening to them, and it has created a weird sense of anxiety. Further, do you.
Remember that Radio Lab episode about the person who could hear their own heartbeat, and then yeah.
Yeah, I think that that's I think that might be what's going on. And I don't know why that is.
I don't have an answer to that.
Yeah, I don't know. I mean anyway, but that quote that paragraph was from of course Lenek, whom you'll hear a lot more about later in the episode. Who basically invented the stethoscope.
Yep, spoiler sure did.
Yeah. And Hi, I'm Aaron.
Welsh and I'm Erin omn Updike.
And this is this podcast will kill you today.
We're talking all about the stethoscope.
All about it. Yeah, you know, we put this down in like our let's do this as a topic, put it on the list, and then when it came time to do it, we're like, wait, what are we? What do we What is the goal here?
I still don't quite know what my goal is, So hopefully some we'll get something out of it.
You know, I'm really excited because I was like, Okay, for me, it's clear cut, right, like who had the stethoscope? How did it change things? Blah blah blah, all that usual stuff.
I feel like that's the story. I'm really excited about because, like I know very little pieces of it, but the like what the stethoscope has become I think is so interesting to then think back to when we didn't have them and like what it was like. Then. I'm really excited about it totally.
Well, and of course I am excited because, like I want to hear these sounds, even though they give me anxiety or like some some weird creeping sense of unease. I want to understand how you can tell the difference, because I feel like there's when someone listens to your your body and they're like, what are they listening to? Right?
That's what I'm going to talk about. I'm really excited about it. It should be fun, Like I figured, that's the question I want to answer, is like when you go to your doctor and they stick this metal thing on your chest, Like why, what are they what are they doing and what are they actually hearing?
Yeah, Yeah, I'm really excited about this episode. I feel like we're I mean, we always say this, but I like sometimes feeling surprised by the things that we learned, Like there are some topics where we're like we know more the outline of the story. Yeah, and this is brand new.
But what's not brand new is that we start every episode with quarantine ey time.
What are we drinking this week?
We're drinking Music to My Ears because it's kind of like there's some musical murmurs and wheezes.
Yeah, yeah, and Music to My Ears is a tasty little concoction.
You know.
We're we're bringing out the mescal for this one. It's been a while, and maybe some campari in there, some little bitterness, some blood orange juice, a little tart acidic, and then some agave syrup just to help round it out. Suiteen it up, make it delicious and tasty.
I love it. We'll post the full recipe for that quarantini as well as our non alcoholic plussey burrita on our website This podcast will Kill You dot Com and on our social media channels. Do you follow us on social media because we're there.
We are there, and we are also on our website This podcast will Kill You dot Com. It's great. It's got some good resources like sources which we put on our website for each and every one of our episodes. We've got links to merch. We've got some cool merch.
Check it out. We've got links to bookshop dot Org, affiliate account, our Goodreads list, links to music by Bloodmobile contact us form a submit your first hand account form transcripts transvention that we have those probably more things outdated pictures of us that we really need to update.
We will maybe by the time this episode comes out, they'll be updated. So check it out and see see how old the picture. Sorry, this podcast will kill you dot com.
Wow. Okay, before we go to off the rail, should we get into the content? All right? I think we should.
I think we really should.
Let's take a quick break and then begin.
What the heck is the stethoscope? I feel like everyone knows what a stethoscope looks like, but I'm gonna describe it anyway, just in case. A stethoscope is a metal piece at one end, and this metal piece usually has two different sides. One of the sides is more open and curvy, and it's called the bell side. It usually has just like a rubber ring around it. And then the other side is more funnel shaped and it's covered
with this thin, usually plastic diaphragm. And then this metal piece is connected to tubing that then splits into a y shape. And then is connected to ear pieces that we stick in our ears. And at its core, a stethoscope is just a tool to help amplify sound, and we use it to amplify the sounds in your chest
for the most part. And Aaron, I know you're going to talk about like how it came to be and how it's changed because it didn't noise used to look like this, and later we'll talk about like does anyone still use the stethiside and what are they using instead and what's going to replace the stethoscope. But for this part, what I wanted to kind of focus on is like what are people listening to and listening for when they're
using a stethoscope. It's funny, I feel like I take it a little bit for granted that like we get a decent amount of training and how to use the stethoscope in med school and so it's like, oh, of course you're listening to heart and lungs. Everyone knows that. But it's kind of been fun to go back and be like, oh, what for someone who has never put their ears to a stethoscope, Like what are you hearing
and what are you listening for? Right? So the two main things that we're listening to are your lungs and your heart. To a lesser degree, you can also use a stethoscope to listen to bowel sounds if you stick it on the abdomen, but like I don't, I'm just personally not a huge fan of bowels sounds.
Can you Can you say more.
Bowel sounds like present or not present, or like hyperactive or not hyperactive. So they're just like not that interesting when you think about like the different pathologies, Like you
can't get that specific with the stethoscope on a belly. Okay, In any case, we're mostly using a stethoscope to listen to what's going on in the chest cavity, and so I want to focus first on the lungs and then on the heart, and we'll talk about like what is a quote unquote normal sound and what are the abnormal sounds that we're listening for to try and diagnose if something is a miss. And to do this we will
use some recorded lung sounds and heart sounds. So thank you so much to the open source databases that exists for us to get this, and they will all be linked in our sources as well. All Right, So the first thing is lung sounds. The sound that you hear when you are listening to a lung is literally the sound of air moving through the lung tubes, right through your bronchi and through your bronchioles.
The name for.
These lung sounds is vesticular breath sounds. That's the technical term for it, okay. And you hear these vesticular sounds mostly on inspiration, so when you take a breath in and then the first part of expiration, and then they kind of fade out after that. So I'll play a quick clip for you to be able to listen. So that click click clicking that you hear is actually the heartbeat, and we'll talk more about the heart in a second. And that kind of does predominate in that particular clip.
But what you hear in the background is that very gentle, very even whooshing right.
It's like rhythm, very wave sounds.
Waves sounds, that is lung sounds. Those are vesticular breath sounds. Nice healthy inspiration, expiration. The deeper that you breathe in, the longer that you'll hear it. What's always amusing is when you ask people to take a deep breath, they'll usually go for a really long time and then for a really long time, and like half of that expiration you're not hearing anything. But that's a bit of an aside.
I always feel like stressed because I'm like, am I doing this fast enough? Am I breathing deeply enough? Are they going to miss something? Because I'm like and then they're like, I'll breathe in, and then they're like, okay, breathe out, breathe in, and I'm like, that's too fast, I read.
Do it's because we're only you only hear that first part of expiration, so the expiration is is less important except when there's pathology. So we'll get there. But the first thing that you might notice if you're listening for lung sounds is if you don't hear them at all, because if you don't hear lung sounds when you put your stethoscope over someone's lungs, then that means that something is going on, right, you should hear air moving in and out. If you don't, it might mean that there's
a blockage. So that could mean a mass, it could mean so much fluid that there's just like a chunk that you're not moving air. It could mean that a lung has been collapsed, so there is literally no lung there for you to hear. Or it could mean that you have such massive obstruction, even from something like asthma, that there's just not air moving in and out enough that you can hear it with a stethoscope.
And so this would be like on one side you would hear breath sounds because someone would have to still be breathing, and on the other side you would hear no breath sounds, and that would indicate pathology potentially.
Yeah, okay, yeah, so that's just breath sounds present, breath sounds absent. Then there are a couple of different abnormal lung sounds that we will focus on, and neither of these are specific in and of themselves to any like one particular diagnosis. None of the exam that you get with a stethoscope is like an absolute clincher. Necessarily, they're all part of an overall exam and findings that are going to help you try and figure out what's going on.
And the types of lung sounds have a lot of different names in older literature and newer literature and across the globe, but I'm going to use the names that the American Thoracic Society tends to use, and so that is wheezes, and ronki and ronchi are just lower pitched wheezes and then crackles. And with crackles you have both fine crackles and coarse crackles. Now this is not all of the things that you would hear, but this is the majority of the abnormal or also called adventitious breath
sounds that you would hear. So let me play a clip for you of crackles. Do you hear that?
M hmm.
They're kind of I feel like crackles is a really good word in all honesty, because they sound crackly, like you're mixing up a piece of paper or something like that. There's other descriptions that I really love. There's a description for fine crackles, specifically that they sound kind of like if you join velcro together and then separate it. That's another way to describe the fine crackles. And that clip that I played is a little more coarse crackles than
fine crackles. What's causing these crackles? Fine crackles happen when you have inspiration that's opening these really small airways that have been collapsed, and that kind of collapse can happen for a number of different reasons. So you might have crackles, fine crackles, or course crackles in something like pneumonia. Yeah, you might have crackles with something like heart failure because
you have fluid in the lungs. Or you might have coarse crackles with something like chronic obstructive pulmonary disease or COPD or bronchitis. There's a lot of different types of pathology that can cause crackles. Then there are wheezes. Wheezes are one of my favorite sounds when in the lung, even though they're not like, no one wants to be wheezy, it's not good. But let me tell you this clip.
Why are they your favorite?
I think that they're my favorite because a lot of the times with wheezing, you can really diagnose something with wheezes and then treat it a little bit more specifically. So with wheezes we're usually thinking about asthma or COPD. Are those the only things in the world that can cause weezes? Definitely not. If you have like a foreign body ingestion, you might have a focal wheeze, and the wheeze is happening because there's that's trying to squeeze through
a really small constricted tube. So let me play the clip so you can hear that.
That sounded really horrible. That makes me feel like I can't breathe.
Yeah, so in that clip, there's more inspiratory than expiratory wheezes. You can get both. It's not a good sound. You definitely know that, like there is something very much wrong going on here. But a lot of times with wheezing, it's something that we can then say, oh, based on the other things that I know about this person who's coming in here and this lung exam, I know what the next treatment is going to be. Does that make sense? I think that's why I like this. It's not like they're good.
So if there are more inspiratory wheezing than expiratory, then what what does that indicate?
That there's probably like a very detailed answer to that question that I don't specifically have. You can hear both inspiratory and expiatory whezing, but classically something like asthma is described as expiratory wheezes, but you can certainly get both inspiratory and expiatory wheezing in something like asthma, COPD, et cetera. Okay, so that's like the main types of lung sounds that
you might hear. There's nuances there, there's other types of sounds that you might hear too, but these all just give the listener a bit of an idea about what is going on in the lung and then maybe what to do about it.
I have some questions, okay, okay, so when you're listening to first of all, where are you listening to the lungs? What is the best place to put that little end of the stethoscope.
Yeah, it's not about one place. It's about listening in multiple places and comparing them. So people are always going to listen minimum in like four different areas because the two lungs and the top and the bottom. But then there's also places that can stay kind of hidden, and so sometimes you have to listen around like towards the front side to get like the right middle lobe. And really the more places that you listen across the back,
the more information that you're going to gather. But it's really about comparing one side to the other, and comparing the top to the bottom to listen to the whole lung, okay, And it's not just so, it's a really good question of where do you listen, because it's not just the sounds that you're hearing, it's also where you're hearing the sounds. Are you hearing crackles everywhere or do you only hear them in one specific spot? Are you hearing wheezing everywhere
or just in one particular spot? And so that information is also really important as part of this whole exam.
Okay, when it comes to something like crackles and wheezing and stuff like that, you know, like you said, the location of the you know, the origin of that or how pervasive it is or whatever, that's important. But what about the degree, Like, if you're hearing fine crackles versus coarse crackles, what does that tell you if any or is it just like a descriptive?
Yeah, so it might give you ideas about what the underlying pathology is. If it's more course versus more fine, you think of slightly different pathology. And if it's like runcous, like those low pitched wheezes versus those high pitched wheezes, it's gonna clue people into different types of disease that's going on. If that makes sense, Okay, there's like too many different lungs to get into, like all those specifics.
Well, and then that kind of brings me to another question, which is, like we use the stethoscope. It's a tool. How often is it the last line? Like, how often is it the diagnostic tool, rather than like, oh I hear some wheezing, Oh I hear some crackles, We better get you an X ray to see just how bad it is or whatever.
Yeah, it so depends on the situation that you're in.
Right.
If if somebody is in an emergency room and they look super sick, no one's going to end with the stethoscope, right, You're going to be getting imaging, You're going to be doing more things, and you might be treating something. Even if you think that your lung exam sounded totally normal. Right, It all just depends on the situation. There are definitely situations that this stethoscope might be the last part of
your diagnosis. For example, a kid who has a known history of asthma who comes in having trouble breathing, You put a stuff the scope on their chest and they're wheezing, then you'd say, okay, let's treat this as an asthma exacerbation, and so then you treat it and then see if they get better by listening to their lungs again. So there are situations where it's still something that you very much use and would not then need to do further imaging or even like further imaging might not tell you
all that much. But as we'll talk more about like throughout this episode, there are a lot of things about the stethoscope that are limitations, I guess of the stethoscope, and so there are a lot of new modalities that are much better for making diagnosis compared to the stethoscope.
Right, because there are presumably a lot of lung pathologies that you wouldn't be able to hear through a stethoscope, but you would be able to see in imaging.
Yeah, lung and heart especially and heart.
Yeah. Okay, so then that's sort of another question, and this applies to both. This is just like stethoscope broadly. Yeah, how subjective is it? Like obviously you can take these classes or like in med school, you're trained. Okay, this is a wheeze, this is a crackle, this is fine. Crackle course, crackle. Yeah, a lot of the heart stuff that we haven't touched on yet and then be tested on that. But how subjective is it?
Yeah, that's I think one of the biggest, the biggest questions. There's huge inter user variability in stethoscopes. That's one of the biggest downsides of them. What one person hears and what another person hears, they might describe totally differently. They might hear things totally differently, and especially when it comes to a lung exam, the lungs change over time, and so what one person hears at one moment, another person might never be able to hear again because that sound
might disappear or move or something like that. So there is definitely a lot of variability. There was a paper that I read that was like lamenting how medical students are just no longer trained in the stethoscope, and I was like.
Come on, like, I think I read this was a little much. Yeah, well, it's like all of these papers seemed so dramatic. They're like so drum already holding like a funeral for the stethoscope, and I'm like, I've never seen a doctor without one, even if they don't use them, like, come on, now.
I do. I think that it's it's such an interesting Medicine has this tendency this is sorry, this is I wasn't gonna riff like this until way later in the episode, but.
Riff away, I love it.
Medicine has this tendency to like really dramatize new technologies as being like the end of the practice of medicine. And I think the stethoscope has absolutely gotten caught up in that right where it's like, well, if students can't
use the stethoscope, then where has medicine gone? When it's like, sorry, ultrasound is great, you know, right, But at the same time, like I I can say, and this is just like me as an individual and of one, I use my stethoscope very frequently, almost every day as a primary care provider, especially one who sees kids. And so I don't think that we are at this day and age in twenty twenty four at the point where anyone's throwing their stethoscope out the window. And I do think that it still
has clinical uses. And sure, maybe someday it won't and we'll be able to replace it, and that's okay, But right now, it definitely still has its place, and it also isn't the only thing, and it's not perfect for sure.
Yeah, I mean, medicine has such a short memory where it's like, I know, we think that somehow we are here and this is how we've always been here.
Well, that's why I'm so I'm so excited Aaron to hear about like when this came, because I know there was like controversy when the stethoscope came to be, and I just I love, I'm excited for it.
But onto the heart. We're still on the heart organ to discuss.
I feel like the heart is what probably people think about and focus on the most when you think of
the stethoscope. I don't know, maybe it's a toss up heart and lungs, but the heart is a big thing that you're also listening to and probably what gets even more focus in med school training in terms of the specifics of what you're trying to listen for and the diagnosis that you're trying to make when it comes to heart sounds, because with a stethoscope, with a well trained ear, as they say, and a stethoscope, you really can make diagnoses of the heart function a little bit better than
you can with the lungs. At least that's my interpretation as a not perfect provider. I don't know whatever. So what is someone listening to when they're sticking a stethoscope on your heart on the front side of your chest. The first thing, of course, is the heart sounds that you would expect to hear, and that is loub dub lob dub. Let's take a listen to a normal heart, shall we love dub love dub.
Yeah, right, pretty much what I expected.
Right, do you know what those sounds are?
Your heart? Technically right erin, right erin.
Oh, that was quite funny, So yes, it is your heart. The first lub, that first sound, also called s one, is the beginning of what's called sisterly and that is when your heart is contracted. So that sound that you hear lub is actually the sound of your valves. Specifically, the valves are that go between the top half and the bottom half of your heart, so your mitral and tricuspid valves snapping shut. That is the sound. It's a
snapping shut of those two valves. That's that first sound that you're hearing, and then the second sound that you hear dub is the beginning of diastily, and that is when your heart is relaxing, it's filling back up. And the sound that you're hearing is the pulmonic and the aortic valves closing, so the valves that block off your heart from shunting the blood to your lungs and the rest of your body. Right, So those are the two sounds that we expect to hear S one s two.
It's the closing of the first two valves and then the closing of the second two valves. And there's a lot like that sounds just like wow, there is so much pathology that you can hear in between those two sounds. If those two sounds are split in certain ways, and if like one sound is stronger or quieter, where you're hearing one sound as stronger than the other. So there is like quite a lot of pathology that you can
actually distinguish within heart sounds. The biggest thing, like the most obvious thing that we're looking for in terms of like pathologic heart sounds are murmurs. So if the sound that you hear love dub are actually just the closing of valves, those are kind of discrete sounds right, Lub dub lub dub. Murmurs are when those sounds get blurred a little bit, and they get blurred because of turbulent flow.
And so what a murmur sound tells you is that something is going on with the valves, which one depends on the murmur and depends on where on the chest you hear it. But it means that there's something going on with the valves so that the flow of blood across those valves is no longer a nice linear flow like it should be, and it's turbulent, and so it
causes woushing type of sounds that you can hear. Let me play a couple examples of like the most classic kind of murmurs, because I think it'll give you a really good sense of how different it is from just a love dub love dub. WHOA right you hear how different that sounds?
Yeah it's not? Yeah, yeah.
So that one is a murmur called aortic stenosis. So your aorta, of course, is what connects the left ventricle, the left side of your heart to the rest of your whole body. And that valve is supposed to close at s two. It's supposed to be open during sisterly when your heart is contracted and blood is supposed to be able to flow to your whole body. But what can happen sometimes is that valve gets stenotic or hard, and so then it doesn't open all the way, so
it's more narrow. And when that happens, when the blood tries to go across that valve, it gets forced. Think of like forcing, like sticking your finger on your hose or something. And the water that's previously just flowing quietly is like whoosh.
Right.
Yeah, So you hear this very specific kind of murmur that's like hu where it gets louder and then quieter. It's called a crescendo de crescendo, I'm telling you. Murmurs are like that's a whole language, a musical.
Yeah.
Yeah, And so if you hear that, especially at specific places, then that can tell you that murmur, that specific murmur means that someone has aortic stenosis. Without needing any additional imaging. You can say, well, you have an aortic stenosis, okay, if you hear that murmur.
Yeah, there's lots of other kinds of murmurs, and depending on where and when you hear them and what they sound like, that can tell you is this murmur because someone's mitra valve isn't working correctly?
Is it because someone's tricuspid valve so on the right side of their heart, Is that the one that's not working? Is the murmur in sistily, so when the heart is contracted or is it in diastily when those ventricles are trying to fill back up? Right, There's a lot of different things that you can get from when that murmur is and what it sounds like.
Interesting, I know.
So there there is definitely a lot of pathology that you can't hear with the stethoscope. Even that example that I gave of aortic stenosis, if it's really severe, you actually don't hear it at all because now it's just like such a tiny valve that you just can't you can't even hear the flow across that valve, okay, And there is varying degrees. For example, let me play a great This is a great classic med school murmur that
happens with what's called mitral regurgitation. So when the valve on the left side of your heart is a little floppy, then sometimes you get backflow of blood during when your blood is supposed to be squeezing out to your aorda. So if you listen to this whoa, So that one
sounded different, right than the previous murmur. Yes, so that one also had a fun little what's called an extra heart sound that you can get when you have other kinds of heart pathology, Like if your heart is very dilated, then you might get these like extra instead of love dub,
it's like love da dub loub bub bub thing. So you might hear that murmur in someone if that pathology is severe, if you maybe have a crappy stethoscope or don't know what you're listening for, or if it's just not that severe you have like a little bit of regurgitation, then yeah, you might not hear that with a stethoscope.
There are other modalities like ultrasound, Gonna keep saying it, where you would be able to see the blood flow because you're actually seeing the blood rather than just hearing the blood flow. So that's like the main and most obvious kinds of things that you'd be listening for in a heart and really it all comes down to trying to get a picture of how the valves are working and how the heart is squeezing a little bit of
information about how it's squeezing. And you can get all of that information just by listening for these murmurs and listening at different places on your chest. So you asked when we were talking about the lungs where you listen. There's four main places that people listen to listen to the heart, and those are named after the four valves, so aortic, pulmonic, tricuspit, and mitrol. All physicians take money. Haha, that's rever.
It took me a second.
I was like, whoa, Okay, sorry, that's how we remembered it in med school. But so depending on what type of murmur you hear and where you hear it, it can give you clues as to what that pathology might be. And then there are degrees of like is it a really loud one or is it a really soft one?
Does it start out loud and then get softer? Like there's so much that like people who are really really good at murmurs would be like the joke is like if a cardiologist can just like touch their stethoscope to someone's chest, they'll hear a murmur that a med student would have to like listen really closely with the best possible stethoscope to hear. There's like all these jokes about it.
But that's a really good joke, isn't it.
I'm just hilarious. I told it really well. But that's like how you rate the degree, Like is it a one out of six, a three out of six, blah blah blah.
That's there is like a scale.
Yeah, there's a scale out of six on how loud a murmur is?
Okay, interesting, And then like presumably, I mean this is getting into like other things, not stethoscope, but like presumably then that is do we do surgery? Do like what are the steps that you take?
Totally totally? What are the next steps? It all depends on what that murmur is, how long has it been there. Because there are lots of totally benign murmurs, especially in childhood, these tend to be often described as musical murmurs. The ones that we listen to we're all very pathologic murmurs. But there are lots of different flavors of murmur, and some of them, if someone hears would definitely choir follow
up and some of them probably wouldn't. Okay, It all just depends on like how old is the person, is it the first time you're ever hearing it, et cetera, et cetera. Right, so that's what we do with the stethoscope. We'll talk a lot more about like how far we've come. But that's like when someone sticks a stethoscope on your chest. That's what they're trying to figure out is does it just sound like love dub and like or does it sound weird?
Yeah?
There you go, Aaron, I had this guy come up with it. How did we do anything before it?
Oh? Those are great questions, and I can't wait to tell you what I can of the answers to them right after this break. We've kind of talked about this already, Aaron. But truly, is there anything that symbolizes doctor more than the stethoscope?
I mean, the little uh what do you call it? The snake or whatever? Yeah? No, no, it's I mean.
Like, okay, I thought maybe the white coat could also count shorter, but then like you could see a picture of someone in a white coat and think, oh, maybe they're a scientist who.
Works in a lab. Yeah, it's a little more generalized.
Yeah, but the stethoscope. That's the thing that acts as the visual cue for doctor.
Yeah.
It's included in every single doctor Halloween costume, any like kids, doctor play set, any toy figurine of a doctor. If you Google image search just the word doctor, which I did, nearly every single picture features a person in a white coat with a stethoscope. I will note that the first picture that did not include a physician with the stethoscope was Mic Dreamy from Anatomy. I can't remember the character's real name.
Was it Jared m It does start with a G, I think Nope, anyway, dream Mick Dreamy is the gray hair guy, right.
I don't think. I don't know if it started out gray.
Oh.
I never finished the show. I stopped when one of the characters turned into a ghost.
And yeah, I remember that we had an elvad too, right anyways.
Fifteen years ago. But studies have shown that doctors with stethoscopes are perceived as more trustworthy than those without, which I think is fascinating. Huh. The stethoscope is such an establishment, It is such an integral part of practicing medicine, even if it's not used that it seems impossible to imagine a time when it didn't exist, more a future without the minute, although as we'll discuss, that does seem to be the future that some people are envisioning. It's more
controversial than I bargained for. I did not expect to see articles with headlines like bring back the stethoscope, save this, you know, relic of medicine, And I'm like, really, like.
It's hilarious to me how much drama there can be in medicine sometimes about things like that.
Right, I was like, we just talked to me, just mentioned Gray's anatomy. Of course there's drama in medicine. But as it turns out, the stethoscope is actually a lot younger than I expected it to be, and its development marked the beginning of a huge transition in medicine and in the relationship between patient and doctor. So let me take you back to the second half of the seventeen hundreds.
Medicine during this period of time was still very much under the spell of Hippocrates and the humoral theory of disease, where illnesses, of course, were thought to be caused by an imbalance in the body's humor's blah, blah blah. Human anatomy was still in its early stages, since dissections had long been seen as sacrilegious and only recently were people beginning to develop an atlas of the entire human body.
And as a result, this belief persisted that most illnesses were not localized but systemic, owing to this humoral imbalance. And I'm talking the origin was systemic, not the effects were systemic, right, right, And so things like heart disease, liver disease, illnesses associated with the lungs, they weren't really conceptualized the way that we think of them today. Diseases of the heart were known, but symptoms indicative of heart
disease weren't really considered, if that makes sense. So like someone has a symptom of something and you think, oh, that symptom is in their heart, but it's a systemic disease. I think it's their entire bodies humors that are imbalanced, not the anatomy of their heart is actually not functioning the way that it should.
It's like their heart isn't working because the rest of their body is off balance.
Yes, okay, yeah. And part of what perpetuated this was that in the late eighteenth and into the nineteenth centuries, physicians were limited in what they could observe in a patient beyond what the patient themselves could tell them, which is important, as we know, and it sort of I
think has over time. We've now the pendulum has swung in the other direction to some degree, but it doesn't always capture all of the elements, right Like, someone can feel completely not sick whatsoever, and there could be something that shows up there on whatever imaging, or shows up
even with a stethoscope. And if you remember from our fever episode, watches with second hands weren't developed until the sixteen nineties, which only then allowed physicians to accurately measure pulse rate, and the mercury thermometer, invented in seventeen fourteen wasn't regularly employed by physicians until the early to mid eighteen hundreds, and the incorporation of these tools into medicine, especially for diagnostic purposes, was part of this larger trend
in the scientific search for truth with a capital T, like objective truths that could be measured and standardized so that their meanings remained constant across individuals, across space and across time. In medicine. It seemed to be driven in part by a mistrust by the physician of the patient's account of things. The physician's like, well, I can't trust what you're telling me. I gotta see it for myself. I got to hear it for myself. I gotta smell
it for myself. Whatever. It is not necessarily malicious, but a recognition that people's accounts can vary, sensations can feel differently to different people, and that there could be a disconnect between the way someone feels and what they're experiencing, like fever, for instance, where you might feel freezing cold, but actually your temperature is burning up low grade fever. One of these tools or methods to make objective measures in medicine was developed in seventeen sixty one by a
physician from Vienna named Leopold Irenbruger. Essentially, percussion entailed tapping a person's body with their fingers and then listening to the sounds produced, which were supposed to tell you the quote vitality of the internal organs, especially the heart and lungs, so you would like thunk, yeah. And he wasn't the first to listen to the internal goings on of the organs, but he was among the first to write about it
systematically and apply it to specific diagnoses. So like, maybe a dull funk meant that the lungs were full of fluid, or a hollow echo meant the spleen was doing just fine. I don't really know the guidelines I'm making. I made all of that up, but neither did the physicians who came across his treatise, which apparently included only the vaguest of descriptions.
Gotta love that.
Yeah, right, He's like, let me tell you about this method. It's really great, and you just tap your fingers on a person's body and then listen, and then what you hear will tell you everything about what the person has the end, and so this sort of lack of description probably had something to do with his method of percussion not catching on the way that he had hoped, but it was also because what he was proposing was very
much outside of the norm for medicine at the time. Because, for one thing, this method of percussion required physicians to think of the body and disease in anatomical terms, which was still very much a new concept. Anatomy took a backseat in most explanations of the day of how disease
began and how it developed. And secondly, to successfully employ the percussion technique, physicians really had to get in there, like up close and personal, had to touch their patients and then they would have to bring their head close to their chest or whatever part of their body to get a good listen. And this was something that would you know, called into question the physician's dignity, since manual labor was considered beneath the physician at the time. They
were intellectuals, not common laborers. They used their minds, not their hands.
I find that so interesting and not at all a part that you learn about medicine.
Yeah. Yeah, well, and it's also okay, let me read you a quote that I think even brings a little bit more color into this picture. Quote. In particular, the physical intimacy required by percussion threatened to undermine the professional standing of the physician, even to place him in a class with the surgeon, over whom he affirmed both medical and social superiority. End quote.
Wow it's a surgeon. Yeah, run deep.
Yeah they told Wow, So I think it was. It was really interesting, Like the divide was so stark and the hierarchy was so well established where a physician was a thinking man. He was I mean, and I say man because pretty much yep what I mean and uh and yeah. So it was like, no, they make diagnoses with their books, with their minds, with the way that they take in all of the data. They don't cut, they don't touch. That's just fascinating to me. Oh, Aaron,
this profession, I know, I know. And so Aaron Berger's percussion had a lot working against it and it largely faded into obscurity, but it did catch on in a handful of doctors who passed it down to their trainees. One of these trainees went by the name of Renee theotfully Hyacinth Lenek. I'm just gonna say Lenek from this point forward. Lenek was born in France on February seventeenth, seventeen eighty one. When he was just five, his mother died from tuberculosis, and his father sent him to live
with a great uncle. His childhood and youth was filled with playing the flute, reciting and composing poetry, learning Latin and Greek, and going to the countryside for fresh air. When his asthma acted up and I just need your Okay. I found this paper from like the nineteen twenties that was celebrating the life of Linek. Like no one was higher in this person's esteem than Linek was. It was
the most praise. Okay, let me just get to it. Quote. Okay, from this land of salt sea breeze, gray rocks and downs and druidical forests of mystery came the calm and prodigious intellect of one comparable only two Hippocrates, in his vast store of medical lore and almost superhuman accomplishments. End quote.
Okay, I mean did someone's chest.
I mean he did a lot, but like I know, I mean he also was the first to besides the sethoscope, he did other things too. I think he died lenex cirrhosis. He described that for the first time.
I think there's rules named after him and stuff. Yeah, and he.
He identified melanoma as not as being a cancer and separate from he like a lot of people thought at the time that was tuberculosis, like the black granules that came to the surface, and he's like, no, this is not that anyway. But when he was when Lenek was fourteen and a half. He started as a student in the School of Medicine of the Hotel due at Nance
and quote. Soon after he was appointed military surgeon of the third class at a salary of something like nothing a year out, which, first of all, a few things to unpack. I love the description of something like nothing. And then soon after he was fourteen when he enrolled to imagine, like a fifteen year old.
How soon are we talking couple years, five years, one year?
I would think he was probably within a few years.
Oh my god.
Yeah, So in this in his stint, he did a bit of surgeoning with the troops, and then when that was over, he continued his medical education in Paris, which of course is where he invented the incredible device, for which he still receives just untold praise from like the author of that article. The story goes that as he was on his way to the hospital one morning in September eighteen sixteen, he saw some children playing with a
wooden beam and a pin. One kid held the end of the piece of wood to his ear while his friend scratched the other end with a pin, sending little signals. Okay, did this actually happen? I probably shan't. I doubt it. I highly doubt it. I don't think he ever wrote about it personally. I think it only shows up in people who wrote about Lennek how funny.
Yeah, that fateful day he remembered seeing those children, like come on.
But maybe it did happen. Maybe, And he I think, you know, if it did happen, the incident would have
probably been soon forgotten. If not, he had a particular patient, and like you heard about in the first hand account, he couldn't use his usual method of percussion or direct ouscultation, where he like put his ear directly on this person's chest because his patient was a young woman with suspected heart failure, which we didn't mention this at the top, but we included audio of a clip of someone who has heart failure.
Yeah, in acount those crackles, the crackles, yeah yeah.
And so yeah, he was like, well, I don't want to get up close and personal. This is really uncomfortable. And so then he the first hand account, he rolled up that piece of paper and was like, whoa, I can this is amazing. This has potential not only for this particular patient in this particular situation, but so many things like. He immediately saw potential, and over the next few years, Lenek put this new tool to work and he called it the tethoscope, meaning I look into the chest.
He played around with different designs and materials, starting with a piece of paper tightly rolled like he described, and then he would like glue the ends to try to create more of a I don't know, capture the sound because it would come out and I don't know how anything about like audio engineering works, which is you know.
Yeah, that was the thing I thought about looking into. And then I was like at physics and me don't get along, so I didn't.
And then he tried different materials. He tried ivory, he tried gold beater's skin, which I looked it up. It's made from an animal's intestine, so like yep. Then he tried various woods, and ultimately he landed on soft woods with an opening at the end. So Aarin you described this modern stethoscope. Yeah, if you saw, if you just like saw in a random museum or antique store or something, one of Lenex's early stethoscopes, you would not recognize it
as a stethoscope. You'd be like, what is this? Like long pin it's like a wooden cylinder.
I would because I've seen pictures of them. But like, if you haven't seen pictures of them, you would not You would think it was like just a stick thing.
Yeah, it looks like a stick. Maybe there's like a flaring out at the end. Maybe, yeah, maybe, which is funny because I think that, like now, our image of the stethoscope is of the modern stethoscope, which is not that that old, and so it's it's just funny, it's
like anyway. Yeah. But so in eighteen nineteen, Lenek presented his stethoscope to the world with the publication of his two volume on media Ouscultation, available for the low price of thirteen francs or sixteen if you wanted a stethoscope included with it. He made a bunch of them, which is a complete stroke of genius, Right.
That is really funny. Here's the book and here's the thing.
Yeah, He's like, do you don't have to wonder what this is like? You don't have to wonder what these noises I'm describing. See for yourself, here for yourself.
Love it.
Yeah. His book and the Stethoscope took off in popularity, probably in part because the device was included with it, or you could you could buy it. But also because his descriptions of various chest sounds in association with certain diseases were so detailed and precise. Yeah, like let me
read you a quote, Oh I love it. Quote when the patient coughed or spoke, and still more, during respiration, there was heard a tinkling like that of a small bell which has just stopped ringing, or of a gnat buzzing within a porcelain vase.
Right, and like you really understand what you're hearing or what you're supposed to be hearing, or what he was hearing.
Yes, what a way with words like I don't think I would be as creative or articulate.
You heard me hearing I was like, you know, it's like whoosh.
And.
Now put that in writing and there you go. And so in these volumes he created new terminology entirely like stethoscope, but also rails fremidous, cracked pot sound, metallic tinkling, egoffany, bronchophony, cavernous breathing, puerile breathing, veiled puff, and brute. Yeah.
Yeah, some of those words we still use.
It's kind of amazing. I mean, like, okay, maybe I am back to thinking that he's like hypocrites level. But with this tool and his book, Lenek revolutionized medicine. The stethoscope has been called the first major diagnostic tool of modern medicine. Before the stethoscope, there was virtually no way to observe what was going on inside the body except for autopsy, which of course happened after death, or surgery,
which at the time almost always led to death. With this device, Lenek was able to say, these sounds are linked to this disease or this illness, and then he could confirm the location and pathology in autopsy later on, something that again was in its early stages, like the
concept of localized disorders. His book flew off the shelves as this tethoscope picked up speed, leading to more refined descriptions, applications outside of lung and heart sounds like in obstetrics and orthopedics, and then people started to make variations in the design of the device that allowed for better listening. So Lenek, who was only thirty five years old when he invented the stethoscope, would only live to see some of this excitement because, of course, having a diagnostic tool
doesn't necessarily help prevent or treat or cure disease. Linek had never been the image of perfect health, even as a kid, But as the eighteen twenties rolled around, his asthma, his insomnia, and his chest pain got worse. In eighteen twenty six, he had a sense that things were coming to an end. He had a fever, productive cough, shortness of breath, and he'd been a doctor long enough to know the signs of tuberculosis when he saw them, but he had for years denied that he had the disease.
A lot of people in his family had gotten sick and died of tuberculosis, and so maybe it was sort of a matter of just like, I don't this can't this can't happen to me? How can this happen to me? And so finally, in the summer of eighteen twenty six, while in the countryside, he had his physician nephew listen to his chest using the tool of his own invention, what he called, quote unquote, the best part of my legacy and the diagnosis. I don't know, I don't know why I feel so sad.
This is more emotional than I expected.
I know, I can feel tears. The diagnosis was I'm laughing, but I really do feel sad. Yeah, the diagnosis was tuberculosis and he died later that summer at the age of forty five.
Wow.
Yeah, but as we all know, the stethoscope didn't die with him at all. There was some resistance Aarin you kind of alluded to that earlier, like some patients were afraid of this new instrument. Some physicians felt like the physical labor aspect of it gave off too much of a surgeon vibe. But most of the energy was focused on better incorporating the tool into medicine, like how can we use this what are the max how can we
maximize the use of this tool? And so the rest of the nineteenth century was filled with improvements on linex's simple design. In the eighteen fifties, doctor George Phillip Comans developed the first two ear stethoscope. Smaller stethoscopes were introduced so you could carry them more easily. People worked on flexible stethoscopes, and in the early nineteen hundreds, physicians realized that they could pick up sounds better if they stretched a diaphragm over the mouth. Of that little open cup
at the end of the stethoscope. As the century came to a close, it seemed like the stethoscope was here, to say, a permanent fixture in medicine. But is there such a thing us? Yeah, I mean, if there is, the stethoscope is probably the closest thing to it, but its future seems uncertain. At least that's what we've been talking about based on some of these papers titled things like throw the Stethoscope Away, a historical essay and in defense of the Stethoscope and the bedside.
I have some good ones too.
And although these papers are from the last couple of decades, the sentiment of behind this is a lot older, as
is the downward trend in the stethoscope's use. Why is that we've talked about this like other diagnostic more precise tools have come onto the scene that provide better and more accurate pictures of what might be going on, like the X ray machine, which is quite old, and when it was introduced and started to become widely used, it replaced the stethoscope as a major diagnostic tool of lung conditions or CT scans, MRIs, chest radiograph, ultrasounds, and so on.
With these instruments, we move closer and closer to objectivity in medicine in terms of measuring tools, not in terms of bias. Medicine is not objective by any means. Percussion was developed and the stethoscope invented so that physicians could better observe for themselves what was going on inside their patient, to not have to rely on their patient's testimony entirely to make a diagnosis and decide on a course of treatment.
But like we've talked about the noises that people hear, the sounds that you hear in a stethoscope, they are open to interpretation, to misdiagnosis, to simply not hearing them at all. And several studies have confirmed that stethoscopes harbor lots of germs like MRSA, although I don't know if they are significant vectors for transmission or if that's been measured.
Oh, there is a paper that measures that it doesn't carry sea diff which is nice than most of the papers.
That's great, yeah, right, yeah, But teaching these sounds can be difficult in that regard. You know, it's like in the ear of the beholder, I guess a squawk to one physician might sound like a bell clang or crackle to another. The ideal diagnostic test in medicine is one that produces results that look the same to every physician, right, Like, wouldn't we want them to be universally yes? No, binary, almost.
We would?
We would? I mean that's the ideal. Yeah.
Is any diagnostic test capable of that at this point?
No? I doubt it, but I mean maybe, but I think we can get closer, you know, And I think that's the whole thing behind it. And this isn't to say, of course, that noting that squawk or bell clang or whatever isn't important, because that might be what gets you to order additional tests to find out what's going on. And the stethoscope itself is I think, an opportunity to keep met present in the room, like grounded in humanity and physical diagnosis and dependent in part on bedside skills.
And I want to hear you like your thoughts on all this, but first let me leave you. Yeah, let me leave you with this quote from a nineteen seventy nine article that I really liked. Quote today, the stethoscope is the old warrior of medicine. Although it cannot compete with the array of elaborate and expensive technologies for which
it paved the way. It clings tenaciously resisting retirement. Its staying power in modern times is based in part on its giving both physicians and patients a sense of continuity with the past. Identified with dependable diagnosis, the familiar object evokes confidence. Most important, it provides those physicians who still know how to use it with good, immediate and low cost information that can eliminate the need for complicated diagnostic tests.
End quote. So, Aaron, what do you think is the art of usuations something we should preserve or is that sentiment just a reflection of the natural resistance to change in fear of the new?
Oh, I cannot wait to tell you Aaron's Opinion corner about this right after a quick break erin It's funny that you ended that section with a quote from a paper from nineteen seventy nine, because I actually I'm guessing it's the same paper.
The one from by Riser from Scientific American.
Yes, yes, I also have a quote from that paper, but it's a totally different quote, and it's like the opposite end of the coin. And I think what it highlights is what you mentioned, which is like, why does the stethoscope represent what it has come to represent in this like push and pull of like new technology and physical exam and all these things. So let me read to my quote from that same paper, yay okay.
Quote.
When the nineteenth century physician chose to make diagnosis less on patient's verbal accounts of their symptoms and more on the physical signs of illness that in many cases he alone detected, he was obliged to make up his own mind about illness. As a medical era, the twentieth century must be characterized as a time when physicians have come to rely less on themselves and more on specialists, tech tgnicians and machines to collect and evaluate the evidence of disease. End quote.
Aaron I almost included that quote.
It's just it's such a good one, because that really is what it feels like. It comes down to where there are people who say that the stethoscope is a mark, like the ability to use a stethoscope to make a diagnosis, to have that good ear like that's the mark of a good physician, and the fact that we are kind of doing away with it, or there are people who say we need to do away with it, like that
is the problem with medicine and blah blah blah. Right, these new technologies are going to replace us as physicians. Like that is that is something that you hear and not just about the stethoscope. That's like a fear of medicine. Like what is the future of the physician in the
face of all of these new technologies? Jeez. I think that the stethoscope and the problems with the stethoscope and the new technologies that exist really get at the heart of that fear that exists in the practice of medicine. My Okay, now for my opinion corner.
Yeah, yeah, I want to hear your opinion corner.
So, like I said, like I use a stethoscope pretty frequently. Do I use it every day? Definitely not. Do I use it on every patient? Definitely not. Do I always feel like I'm really confident in what I'm hearing? Nope, definitely not. I think that in terms of the like future of medicine question, Like the stethoscope is such a
minor thing in that it's like it's a symbol. Errand yeah, it's one hundred dollars or one hundred and fifty dollars, which when I was in med school was super expensive and for a lot of people is very cost prohibitive. But like compared to an ultrasie, compared to an X ray, like it's really a drop in the bucket. Is it useful, Sure, it's still useful today. Is it the end all be all?
No?
Should it be.
A substitute for these incredible technologies that are coming out? Absolutely not. And what I think is so interesting is that, like, there doesn't have to be a reality where these new technologies threaten medicine as a practice. Right, if we use the stethoscope as an example, Yes, there is wide user variability in the stethoscope, and it's an imperfect tool and there's areas for improvement, but it has its place, and so many other tools that we also use have inter
user variability. Right, think about an X ray. Not every radiologist interprets an X ray the same way. And so I think that what this lets us get at is one of the ways that the stethoscope itself and the practice of ouscultation can act and has begun to be improved upon in the same way that X rays and radiology and things are being improved upon and that is data.
So with the advent of digital stethoscopes, you are able to not only augment the sounds that you're hearing by doing things like noise canceling, like reducing ambient noise, and then amplifying the sounds that you hear, which makes it easier for the user to hear the sounds. It also allows for us to record sounds. Recording tons and tons of sounds of normal and abnormal hearts and lungs, allows for things like machine learning algorithms to compile all of
this data. And what's really cool is that you said aran, like, what is a crackle to one person might sound like a squawk to another, And that is true in that someone might say one word or a different word, or interpret something. But if you look at wavefour, there are very distinct waveforms associated with these things that we call crackle,
fine crackle, coarse crackle. Like if you can look at this on a computer screen instead of only relying on your ear to hear the differences, then you can actually pick up on things in a much more specific way by combining the digital stethoscope with imaging of that sound in terms of waveform.
Which is awesome, it's so cool.
But there's so much more than just digital stethoscopes. And if there is one single tool that may spell the downfall of the stethoscope, it's another pretty old one that has gotten upgrades in recent decades, and that is the ultrasound.
So specifically, what is called point of care ultrasound. And I'm not going to get into details of ultrasound, because again, physics and me are not friends, but everyone can probably picture an ultrasound machine if you've ever seen, either in real life or in a movie, someone getting an ultrasound of their baby, right of their fetus. So ultrasound uses sound waves that bounce off of tissue and then are reflected back into a transducer and then interpreted as these
magical black and white images. And while we all might think of an ultrasound machine as this giant, bulky thing that they wheel into the room and they squirt all this gel and it's a huge screen with all of these buttons, because of advances in technology, there are now ultrasounds that plug into your smartphone that are literally just the size of a transducer, or even ones that are an entire ultrasound that's the size of a tablet or
a small laptop. They're really portable, they're much less expensive, and while a lot of these, at least today in twenty twenty four, don't have the resolution of the really big, fancy ultrasounds, they do a really amazing job even in relatively inexperienced hands, first year medical students who are learning how to use ultrasound at picking up pathology equal to or better than a stethoscope in very experienced hands, and that includes in the heart and lungs, but also a
lot of other places in the body too. So I think that point of care. Ultrasound is one of the things that comes up time and time again as being the thing that's going to out seat or replace the stethoscope. And it's true that this is kind of the big thing right now in medical schools that people are really being trained in. And that's kind of like it's the new stethoscope. Is that a thing? It's like, ooh, this is the thing we all need to get trained in.
And as we've talked about on this podcast before, one of the issues with incorporating anything new in medicine is the kind of time lag and turnover yea, and when it comes to ultrasound. One of the challenges is that while a lot of medical schools have really accelerated this training, not all of the attendings have, which means that maybe it's your new trainees who know what they're doing and the people who are supposed to be training them who
have no idea how to do it. There's also issues with any new diagnostic tool, and especially the better diagnostic tools that we get if in inexperienced hands, especially, can have things like false positives, right, so you have this risk where you're going to see things that maybe you're not interpreting the correct way, or you're overcalling things as being abnormal, and really it's not a big deal, if that makes sense. Yeah, So there's downsides to every new
piece of technology. There's ups and downs to every diagnostic and screening tool that we use in medicine. But they're all just a part of the story. And I think that that's what's missed in all of these you know, very heated emotional papers about defending the stethoscope or saying stop listening and look, that's the ones that are defending the ultrasound as being the end. I'll be all like, why does it?
Why is it so binary? Like why can't it be that the stath is right? And it just seems like you're creating this. It's like a it's like an invented argument. And so it's like, who are you debating against? Just a ghost who's like, throw away the stethoscope entirely and get rid of all of them. Let's burn them all in a giant pile, like.
Right, But then if we do that, and then we're relying on computers. Now computers have replaced the physician. Oh, if we do that then, And part of it is like there there is a lot to learn. So part of I think if I give them some grace. Part of the like drive in some of these arguments is like what should we be focusing on when we're teaching in medical school? Sure, because there is so much, so like how much do we need to focus on the
stethoscope versus the ultrasound versus the whatever else? And that's a valid question, you know, like how much do you feel? But it also just like I don't know, it feels like it misses the point.
It feels like it misses the point. It is sort of this like existential fear of yeah, are we going to no longer be needed? I think it does call into question what makes a good physician, which is like a whole separate episode that we could talk about.
I have a lot of opinions on it.
Yeah, I think it's What seems really important to me about the stethoscope someone who's not in medicine, who's that completely outside, is that it's low cost relative to like an ultrasound yep. And it seems like that would be helpful in terms of a decision tree if someone doesn't have insurance or if they don't have good insurance, things like an ultrasound can be really expensive. And so it's like, if you don't know that you need to get an ultrasound,
it's like, is that part of the decision tree? I don't know, you know what I mean?
Yeah? Well, and it gets so complicated too, because then that is, in all honesty and argument for point of care ultrasound over things, because you're able to diagnose better right in the clinic setting without having to send someone and bill for a separate but billing, Oh my god, don't get me started. So you know, and this is
America specific because that's what I know. But Yeah, it's it's all really interesting, and I think that they're at this point in twenty twenty four, the stethoscope still exists, it still has a place, it's still being taught. Will it go away someday? Maybe it doesn't mean the demise of physicians. Yeah, but AI is Aaron Ai, so AIAI might be just kidding. It's also not Aaron hot take. I've got opinions, not worried about it. Bring it on anyways, want to know more. We've got sources.
We got so many sources. So there's that paper that we both loved by Riser from nineteen seventy nine in Scientific American titled the Medical Influence of the Stethoscope. I loved it, and there's a bunch more, but honestly, that one was like, really really great.
I have a lot of sources. Unsurprisingly, so the sounds that you heard, all of those recordings, the lung sounds came primarily from a database that came from a paper titled a Respiratory Sound Database for the Development of Automated Classification. And I wrote down specifically which clips we ended up using. So if anyone wants to find those clips, they also have like literally thousands more. It's phenomenal. There's another really great heart sound database that was an open access database
for the evaluation of heart sound algorithms. But the ones that we primarily used for this so that they could be specific to types of murmurs was the incredible database from University of Michigan School of Medicine. We'll link to all of those. And then I had a bunch of
really fun papers. Some of them were old, like the Clinical Methods, the History Physical and Laboratory Examinations from way back in nineteen ninety and then a lot of those drama papers that we talked about, like a paper from twenty twenty one titled the Future is More Than a Digital Stethoscope. Anyways, we'll post the full list of our sources from this episode and every single one of our episodes on our website, This podcast will Kill You dot Com.
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You to you listeners. We hope that you had fun with this episode. I sure did.
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