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You can measure all the parameters you want. The question is: does it really matter? I know many doctors, and one of my favorite questions is about stethoscopes: I have unanimously the answer "I could just roll a piece of paper and if the room is quiet enough, I can do my work". My grandpa used one made out of wood, just a cone. Once, I was fascinated by a Littmann, with bluetooth audio, I told a friend doctor, that would be great (thinking about a present) the answer was "That is all hype, I can do with a $2 piece exactly the same". I pointed out the possibility to record the sound, to possibly defense in case of being sued: she laughed out loud, said is unpractical to record everything, would take too much time, and again, just a toy.

It's a bit of a head scratcher.

It would require abject incompetence on the part of jellybean stephoscope manufactorers for this to make sense.

On the other hand the reason Litmann stephoscopes are expensive is target market (doctors), build quality and amortization of cost over probably a decade of use. Stephoscopes are a metanym for doctor, and doctors don't want cheap stephoscopes.

It reminds me of the product to make budget incubators for developing markets. I can't find a link but it failed for two reasons, if you can't afford medical grade systems. You probably don't have the highly trained teams needed anyways.

Medicine is in large part a trust based endeavour you need to trust the system you are putting your life at the hands of.

Long story short, this solves an imagined problem. When you consider why X doesn't have Y medical system. It's not because of the price of the kit. It's the entire system that is too expensive. If you can't afford a brand incubator you probably can't afford the it intense cleaning regime needed for the room to put that incubator in!

That label the graph "log dB" which seems a very odd choice if you wanted to show differences

When my kids were little they had a toy doctors set and the fake wooden stethoscope broke; replacing it with a real one was significantly cheaper than paying Melissa and Doug for a new one.

Respectfully, as this is HN, I do not believe that is the purpose of the posted Github repository.

I'm not sure what you are buying, but it wouldn't surprise me if they were done in a factory that does medical grade quality control. While the odds are a medical problem from a non-medical grade stethoscope seem low, it still seems a couple bucks is worth the price. (if we are talking thousands I'd ask for a deeper drive into what that really gets you)

From my experience in manufacturing engineering, if they retail for $7, the cost of goods sold is somewhere between $2.5 and $5.

The thing is that even if you do that, you still haven't made your own stethoscope, which this post is all about.

Really eye-opening to my western-brain that agreed with higher comments simply comparing the process with ordering a unit off Alibaba and having it delivered. Truth is, there's often a million other parameters that could come up and make a project like this really useful & practical to someone.

I'm shocked that you're shocked lol.

$100 for a somewhat specialized, durable medical device that has to meet regulatory standards and will be used daily, possibly for years, by healthcare providers to do patient assessments?

A 3D printed option is going to require a 3D printer, appropriate filament and should be unit tested to ensure it's within spec. The durability is going to be suspect no matter what. It's an awesome project and I'm sure would be a welcome addition to the 'boostrap humanity' catalog of 3D printed parts, but for everyday doctors plunking a hundo on a good tool is going to be a no-brainer.

There are cheap, generic scopes (Sprague-Rappaport types) that are very sensitive but the double tube also causes a lot of noise. There are knock-offs of the Littmann scopes in the market. Then there are the scopes doctors usually buy, which are Littmann, Harvey (made by Welch-Allyn) and Heine, and a few smaller makers. No marketer of a high-quality scope wants to sell it at a $30 or less price point, and if you're going to go higher, might as well place it in the same market as the Littmann ($115+). I'll be honest, for emergency medicine use, the Littmann lightweight scope is good enough and cost about $45 when I bought it. But if I actually want to hear the subtleties in a chest, I'll use my personal scope (a Littmann Cardiology IV). Why choose this one? I already know it and they are very consistent. It doesn't feel cold to the patient and it has the right level of sensitivity without much noise. It is a little heavy. If a dog is bucking around, it can go flying and hurt if it hits someone.

Years ago I had my blood pressure taken by a nurse; this was when they did it manually, squeezing the pressure cuff bulb by hand and listening with a stethoscope. The doctor came in later, saw the numbers and frowned, and took my pressure again. She (both were women) ended up with a reading much more within my normal range.

I asked, joking, “So are you just better than her?” “No,” my doctor replied, “She’s better. She gets more practice. I have a better stethoscope.”

They can become a lot more expensive than $100, but the difference between a Littman Cardiology and the $15 EMT student stethoscope is night and day.

> Currently, the stethoscope resulting from this project functions as well as the market gold standard, the Littmann Cardiology III

If this is true, it's a major achievement.

My daughter's toy stethoscope has actual tubing, some sort of diaphragm, and that seems to work reasonably well!

I'm not surprised good results are available for a few dollars.

People buying stethoscopes tend to be reasonably affluent. Some of the pricier ones just look better and people usually buy them when you get into med school (at least this was the case for me), it's somewhat symbolic so why not splurge.

You probably pay for tests and that the company has to be audited for medical diagnostics standards

It is somewhat of a critical tool, so you don't wanna be checked by a doctor who made their own stethoscope or got one for 3 USD on AliExpress.

How shocked are you, in comparison, that a Claude code subscription is $200/month?

If it’s your everyday carry used in your profession, just pay for a nice one. It’s really not that much.

If someone showed you how to create a functional $30 monitor, you’d still pay more for a nicer commercial one

Is that a lot or a little?

The linked paper has some pictures: https://doi.org/10.1371/journal.pone.0193087

Never seen a UK doctor or nurse attempt to clean, much les sterilize, one.

I regularly wipe my stethoscope, but I have never sterilized it. I doubt many would survive an autoclave.

As an early-adopter of POCUS, I can't quite believe we actually still use stethoscopes

Right. There are plenty of cheap plastic stethoscopes on Alibaba. There are even metal ones in the $2 range. If you want to bang out simple parts in quantity, 3D printing is not the way to go.

It's basically a tube that transmits sound waves from a diaphragm to your ears. Pretty much an extension of your own ears.

Nowadays they do make electronic models. Active enough, I suppose. Can even record sounds.

passive