alt.hn

4/29/2026 at 2:47:31 PM

An open-source stethoscope that costs between $2.5 and $5 to produce

 https://github.com/GliaX/Stethoscope

by 0x54MUR41

4/29/2026 at 9:40:18 PM

Hmmm.

Looking at: https://journals.plos.org/plosone/article/figure?id=10.1371/...

I'm not sure I believe the graphs.

For example, here's another frequency response chart of some stethoscopes: https://www.researchgate.net/figure/a-Frequency-response-of-...

How is it that professional stethoscopes can be that different, and yet this 3D printed one can match a gold-standard one almost exactly?

From what I can tell there's no audio engineering / modelling that's been done here -- It's just some crude openSCAD tubes. And it's not even optimized for 3D printing; a 3D printed tube with a circular cross-section is going to have bridging issues at the top which will result in internal roughness. I have to imagine that results in attenuation. (A better internal shape for a tube is something that looks like "ô". The ^ will print much better)

The type of plastic used and its frequency response, the thickness / stiffness of the silicone tubing, the height / width of the bell... There are so many variables that I think would make significant differences in performance. The fact that they see basically no difference is highly suspect.

This feels like one of those "3D-print everything" fads that was popular a few years ago. Yes, you can make a 3D-printed adjustable wrench, but even the most miserable dollar-tree metal version will beat it in every possible metric.

Likewise, on Alibaba, if you order 200 pieces, I'm seeing metal ones as low as $1.22/pc. I don't believe that this 3D printed one will even be as good as those.

by hex4def6

4/29/2026 at 9:57:27 PM

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!

by rustyhancock

4/30/2026 at 7:39:31 AM

And patients. What would you think if the doctor in front of use is using a plastic thingy that seems more come from a doctor-toy-set?

by f1shy

4/30/2026 at 4:41:36 AM

steThoscope

I normally wouldn't comment just to correct a misspelling, but it's pretty consistent and it's an entirely different sound, as well as being what the thread is about.

by fluoridation

4/30/2026 at 7:16:59 AM

To some percentage of the British population, I fink you'll find it's exactly the same sound.

by OJFord

4/30/2026 at 11:57:58 AM

It isn't always exactly the same sound even when th-fronted, the manner of doing so is regionally distinct and in many cases, to a sensitive ear, a th-fronted 'th' can be clearly discerned from an 'f' based on sound alone. Some accents will make a stronger distinction by softening the 'th' and/or extending it into the subsequent vowel.

by rounce

4/30/2026 at 6:24:01 AM

Thanks!

by rustyhancock

4/30/2026 at 11:56:57 AM

There is something about using quality tools that goes beyond practical.

For example, I like coding on a nice keyboard, and I think I am not the only one here. But realistically, the cheap keyboards that litter offices everywhere work just as well. Simply, I don't enjoy using them, and when it is something you work with every day on a job that pays well, you can afford a few hundred dollars worth of luxury once in a decade.

As someone said, there is also the question of image. If you are a professional, your customers (/patients if you are a doctor) expect you to have professional tools. For example, a contractor arriving with that $10 Ikea toolbox may rise a few eyebrows. Maybe that's all he needs and he can do a terrific job with it, but he may not be taken seriously.

by GuB-42

4/30/2026 at 1:21:27 PM

That is also my productivity hack. It reminds me of video games that gives you reward cues for doing something. Psychological tricks to massage your brain and get you hooked. That's why also like to buy nice stationary. I always look forward to use my notebooks and pens.

by enaaem

4/30/2026 at 12:27:57 PM

And the $10 toolbox needs to only be insufficient once or twice and suddenly the $200 packout makes sense.

For you or I who use the box once a year? The savings are worth the minor hassle - but if you’re using it everyday it only takes once or twice to outweigh the costs.

by bombcar

4/29/2026 at 10:16:43 PM

Yes, if you're going to be using it for the next 10 years, it is worth going for the more expensive Littman if you can. However, I've heard that there are decent Chinese clones, and honestly I've used those $1 stethoscopes in isolation units and they're not terrible for basic pulmonary auscultation.

by davikr

4/30/2026 at 4:43:11 AM

But where do they fail? What does a good stethoscope bring? better and clearer amplification?

by copperx

4/30/2026 at 6:35:14 AM

They are a nicer product to use, by people who are relatively well off and will use them repeatedly throughout the day for a decade. $50 (basic stethoscope) vs $200 (premium stethoscope) is simply not that expensive for a doctor or a family buying a graduation gift, even in poorer countries, given the lifetime of the device (easily 10 years of daily use).

Within that space you get things like soft-seal eartips , where as most cheaper models came with hard rubber, a stiffer spring that holds its shape better, and great acoustics (though most users will know what to listen for by the time they pick one up). You also get less tube noise from movement, less rubbing and scratching under the head, and longer listening time without having to fiddle.

The diaphragm on expensive stethoscopes is more complex, often "floating" — not under tension at rest, but when you press down, a ring tightens it. This gives you both bell (low frequency) and diaphragm (high frequency) response from a single side, so you modulate pressure rather than rotating the head.

Why do expensive stethoscopes fail?

1. You lose them. 2. Wear and tear many parts are replaceable, but repairing the whole head often isn't worth it. Rotating heads can become a failure point, growing lax over time, with grit accelerating the damage. 3. Neck oils degrade the PVC tubing. 4. Alcohol/cleaning wipes also degrade the PVC tubing.

Surprisingly, Littmann hasn't released a dedicated long-term care wipe for occasional use.

by rustyhancock

4/30/2026 at 5:52:42 AM

Yeah, that comment also sent off internal alarms for me also. It would be a great blog post (or YouTube video) for someone to buy a bunch of stethoscopes and objectively test them. I would bet that there is a 10 USD model that is 98% as good as 200 USD models from 3M Littmann. And similar to the neverending arguments about "premium high-fidelity stereo equipment", I bet most doctors cannot tell the difference between the two when the logo/brand is hidden.

BTW: I found the 3M Littmann page on Amazon. The prices are wild: https://www.amazon.com/stores/3MLittmannStethoscopes/page/42...

by throwaway2037

4/30/2026 at 9:57:37 AM

> someone to buy a bunch of stethoscopes and objectively test them. I would bet that there is a 10 USD model that is 98% as good as 200 USD models from 3M Littmann.

It's the same as every other field, cars, phones, or computer cases, you name it. Something can be artificially expensive, but it can also be because it uses better materials, has more features, is built to higher standards. And some things can't be tested properly in a small scale review. Longevity, for example.

But there are factors that influence the premium price. The build construction - quality of the construction, quality and feel of materials, flexibility/rigidity of components, comfort of the ear tips and why not, even color options or the logo that shows you don't cheap out on equipment. Functionality - amplification, frequency response, double sided, 2 diaphragms can be used on children and adults. And then you have nice features like tunable diaphragms, or warm rims/sleeves for making it more comfortable for the patient.

Like for any other product, you'll save on the things you don't care about. The neck is stiff, the earpiece is uncomfortable, the tubing degrades, it's ice-cold, not great for kids or thin patients, but the sounds come in loud and clear enough and it's half the price.

by close04

4/30/2026 at 6:43:56 AM

Not wild when you consider the industry. Although those prices seem high perhaps by 20% compared to international markets.

IIRC in 2010 a Litmann Classic II was $60 today it's $100. That's what most medical students and doctors might use early in their career and it's probably nearly all the benefits of the premium lines.

But even ~$200 for their top tier lines are not expensive given their the tool of the industry.

That's a single year of JetBrains subscription? Or a single month of Claude? For something they could use for 10+ years.

The ~$500-700 electronic with recording stethoscopes always seemed gimmicky to me. But are legitimately useful for people with a hearing impairment.

> I would bet that there is a 10 USD model that is 98% as good as 200 USD models from 3M Littmann

I'd take this in a different direction, a common adage is that diagnosis is 80% history 15% examination, 5% investigation. In this case too the stethoscope performance is a slice of that 15%, and is dominated by the knowledge and experience of the user. If you don't know what to listen for and why (and many doctors won't compared to say a experienced cardiologist) they won't be able to hear it from a perfectly recorded FLAC file.

by rustyhancock

4/30/2026 at 7:21:05 AM

At the higher end it's also just smaller more specialist (cardiologiste, pædiatricians) markets that can command a higher price as a result.

by OJFord

4/30/2026 at 3:00:42 AM

metanym

(taxonomy) A name that is rejected because a valid name (based on another member) already exists for the same group.

by khazhoux

4/30/2026 at 3:05:37 AM 

  metonymy

  (rhetoric) The use of a single characteristic or part of an object, concept or phenomenon to identify the entire object, concept, phenomenon or a related object.
https://en.wiktionary.org/wiki/metonymy#English

by ButlerianJihad

4/30/2026 at 7:46:27 AM

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.

by f1shy

4/30/2026 at 11:07:36 AM

Lots of nurses and EMTs swear by the amplified Bluetooth stethoscopes but unlike a Dr working in a nice quiet office, they're often in much noisier conditions.

by morkalork

4/30/2026 at 12:24:47 PM

The difference between a $100 mic and one that costs ten to a hundred times as much is not how well they work in perfect conditions, but how well they work in the worst conditions imaginable.

Doctors often have the seniority and authority to make the room quiet; nurses and EMTs are often working in much different conditions.

by bombcar

4/30/2026 at 7:41:25 PM

> I could just roll a piece of paper and if the room is quiet enough, I can do my work

That is true. The job is certainly doable. It's also possible to press one's ear against the patient's body to directly listen to the sounds without any tools whatsoever. Stethoscope was itself invented because a male doctor doing that to a woman's chest was uncomfortable for obvious reasons.

There is some kind of difference between a good littmann and a cheap stethoscope. My experience is that the important sounds are just easier to hear with the littmann. Would love to know why that is, and why the cheap ones just can't seem to match it.

by matheusmoreira

5/1/2026 at 8:13:03 AM

Handling recorded data opens up more paths to a lawsuit than it heads off.

by dlcarrier

4/30/2026 at 8:08:43 AM

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

by ZiiS

4/30/2026 at 5:33:37 AM

Amazon in India will sell you a pretty reasonable stethoscope for for $3.

Assuming the usual Amazon, distributor and retailer markups, these probably cost around 50 cents to make in China.

https://www.amazon.in/BPL-Medical-Technologies-ST-01-Stethos...

Many poor countries are perfectly capable of manufacturing their own medical equipment

Background: I have worked in hospitals in Bihar & Vellore Tamilnadu, and have university mates, friends and family who worked in hospitals in Mizoram, PNG, Libya, Nepal, Uganda and even South Sudan.

Even the doctors who worked in South Sudan had no difficulty sourcing basic equipment. They did however, have enormous trouble sourcing funding and trained personnel who were willing to work in a potentially lethal situation.

by KnuthIsGod

4/29/2026 at 5:13:40 PM

The thing is that I can get just as good if not better ones (metal) for $7 all day long, and not have to spend time sourcing and assembling materials, and I don't even have to leave my house to do it.

by stronglikedan

4/29/2026 at 8:40:38 PM

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.

by andrewla

4/30/2026 at 5:55:16 AM

Hat tip. I never heard of "Melissa and Doug" before this post. I found the doctor's kit here on Amazon: https://www.amazon.com/Melissa-Doug-Doctors-Original-Pieces/...

It is adorable!

by throwaway2037

4/30/2026 at 12:30:17 PM

They make a bunch of “old style” toys and some are quite nice, but some start getting toward the “just buy the kids the real thing” pricing.

by bombcar

4/29/2026 at 5:55:33 PM

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)

by bluGill

4/30/2026 at 5:58:46 AM

How much do you think doctor's spend on their stethoscope when they live in a developing country? My guess: About 10 USD. Think about the global demand for stethoscopes for countries where GDP per capita is below 4000 USD. It must be enormous.

by throwaway2037

4/29/2026 at 6:45:16 PM

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

by dieselgate

4/30/2026 at 2:52:03 AM

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

by dlcarrier

4/29/2026 at 9:31:18 PM

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

by felooboolooomba

4/29/2026 at 8:21:35 PM

Here is an interview with one of the researchers behind this project:

https://logicmag.io/bodies/tarek-loubani-on-3d-printing-in-g...

It explains the project and its motivations. It's been a while since I read it (2019), but at the time I found it really fascinating and inspiring.

by krispykrem

4/29/2026 at 10:47:47 PM

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.

by martinwright

4/30/2026 at 2:52:01 AM

Yes, this group had a great interview on The Majority Report w/ Sam Seder. Really both inspiring and infuriating. Inspiring in that human ingenuity to preserve and help others truly knows no limits; infuriating because these are a people having a genocide committed against them and are forced to do such things for basic medical care.

One day everyone will truly be against this.

by shimman

4/29/2026 at 9:33:02 PM

https://www.ebay.co.uk/itm/264691582901

(if eBay kills that link, then for future HNers it's a link to an inexpensive bright yellow single-use plastic stethoscope by a company called Valuemed, which have been available basically forever and are for when you cannot risk getting something nasty on your good Littman)

£1.99 in single unit quantities from a dude on eBay.

These things are so cheap in bulk that they'd ship two in every box of Orthogon Gemini microwave links that I used to fit something like 20 years ago before VDSL was a thing to link fast sites to places that'd otherwise be on dialup. They emitted a quiet beeping to help you align them when they were in aiming mode; the cheap plastic stethoscope made it possible to hear that over wind noise, air handling units, and other such clatter.

I still have a box full of them, despite giving a bunch to the nursery my son went a couple of years ago.

What's the point in 3D printing something for $3 when you can buy them in a bulk box for a tenth of that?

by ErroneousBosh

4/29/2026 at 9:45:56 PM

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.

by Animats

4/30/2026 at 6:10:16 AM

Up next: 3D metal printed version!

by throwaway2037

4/30/2026 at 5:33:04 PM

Something I'd like to see from the hobbyist community: DIY injection molding. Injection molding is a process where the first one is a huge amount of work, and then you just bang them out for a few cents each. Which is why most of the world's cheap stuff is injection molded.

TechShop used to have the machine for it, but it was very rarely used. The injection molding machine was about the size of a benchtop drill press. It had fixtures to hold two dies, a pressure pump, and a guard around the molding area in case something went wrong.

There's an automated one coming out as a kickstarter. Pre-order for $6500.[1]

Now you need to make injection molding dies. This requires a milling machine, and is much easier with software support. The commercial software for planning injection molding is Autodesk Moldflow, but that's overkill for simpler projects. TechShop had that on their computers, but nobody ever used it. There's something called OpenFOAM, but it's not a nice GUI program.

[1] https://www.micro-molder.com/product-page/micromolder

by Animats

5/1/2026 at 10:01:23 PM

Isn't the pressure required to deal with injection moulding kind of ridiculous, and you need to get the die stupidly hot?

by ErroneousBosh

4/29/2026 at 4:23:30 PM

I was shocked to see that a "brand name" stethoscope is $100+ and even generic ones are $30.

by colinbartlett

4/29/2026 at 5:21:40 PM

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.

by jcims

4/29/2026 at 6:57:42 PM

> has to meet regulatory standards

Genuinely curious, what standards exactly, for a stethoscope?

by nomel

4/29/2026 at 7:10:35 PM

A commercially sold hospital stethoscope is a legally marketed medical device made under a manufacturer quality system, with labeling/instructions, device listing/registration obligations, adverse-event/complaint processes, cleanability expectations, liability, warranty, consistent materials, and repeatable acoustic performance.

An open-source 3D-printed stethoscope is a cool project, but unless it is produced and controlled as a medical device, it is not equivalent to what hospitals are buying for daily patient care.

Personally, if I was a hospital or a doctor, it would be a no-brainer for me to go with the commercially sold stethoscopes. All those factors I listed above, if neglected, can end up costing a lot more in terms of consequences. I would rather pay a fixed extra overhead price per unit to sleep well, knowing I don't have to worry or think about those factors at all. And, I would assume, most of the patients would be in favor of that as well.

by filoleg

4/29/2026 at 7:27:16 PM

What standard exactly, for a stethoscope?

I know nothing of this, but it looks like stethoscopes are Class 1 medical devices with 501(k) exemption, and fall under the "Good manufacturing practices" guidelines of Quality System Regulation (21 CFR 820), but that seems pretty squishy.

by nomel

4/29/2026 at 8:16:11 PM

CFR 21 being labeled squishy is a first for me.

by conception

4/29/2026 at 10:11:51 PM

CFR 21 is the whole thing. I'm specifically referring to Part 820, within the context of a stethoscope.

by nomel

4/30/2026 at 2:17:16 AM

Fair

by conception

4/29/2026 at 7:42:02 PM

In the UK it would be Class Im - so low risk device that sits outside the body, with a measuring functionality.

by lukko

4/30/2026 at 2:47:48 AM

To get an idea for required rigor, this is also what eye glasses fall under, in the UK.

by nomel

4/29/2026 at 7:07:12 PM

> $100 for a somewhat specialized, durable medical device...

And one which is treated as a status symbol, at that. Part of the reason a good stethoscope costs more is because it looks nicer, not just because it works better.

by duskwuff

4/29/2026 at 7:41:46 PM

You can get a basic littman for not much. I could afford one when I was a rookie EMT and I've still got the same one many years later.

by harvey9

4/29/2026 at 8:36:32 PM

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.

by projektfu

4/30/2026 at 6:02:11 AM 

    > It doesn't feel cold to the patient
This part stood out to me. Do they use a special material? This sounds interesting.

by throwaway2037

4/29/2026 at 9:17:53 PM

How long do they last? Looks like pretty solid piece of equipment, but are they damaged easily or simply clap out after few years?

by dzhiurgis

4/30/2026 at 4:04:07 AM

I have a littmann cardiology 3 I bought in 2010 and the diaphragms wore out in 2019. By that time, they stopped selling official kits for the 3, so I repaired it with an off brand kit and was given a 4 for Christmas. The off brand diaphragm lasted only a couple years. My colleague has had the rubber tubing wear out. They say if you wear a collared shirt it lasts forever hanging on your neck but if it sits on your skin it wears out, and she always wears scrubs.

by projektfu

4/30/2026 at 2:29:43 AM

I still use one I got in 1994. Replaced the earpieces and diaphragm a few times, but the chestpiece and tubing are original

That's like a little over $3/yr. Can't complain

by dogmatism

4/29/2026 at 10:04:21 PM

> How long do they last? Looks like pretty solid piece of equipment, but are they damaged easily or simply clap out after few years?

They last forever. Why would they break? This is like asking how long floor speakers last.

by bonsai_spool

4/29/2026 at 11:17:43 PM

Speakers sometimes die while sitting unused in their original shipping carton in a dry, climate-controlled room.

The adhesives can age. Foam surrounds can disintegrate. (Ask a Bose 901 owner about foam rot.)

They also can also die from use, and abuse. And finger-poking. And environmental conditions like moisture and UV light.

I know enough enough about old speakers to know that lasting forever isn't one of their usual traits.

Are stethoscopes really as bad as that?

by ssl-3

4/30/2026 at 12:28:52 AM

My first stephoscope lasted about 10 years until the tubing became brittle and started cracking. It's the oil on your skin that does it apparently. It went through a couple diaphragms and I lost an ear piece but used a replacement one.

by zeagle

4/30/2026 at 1:25:18 AM

As other commenters pointed out, rubber/plastics fail.

Littmann sells repair kits.

by NegativeK

4/30/2026 at 3:05:15 AM

Fair enough. My medical classmates regularly used stethoscopes that were purchased by their parents for the parents' own studies but I understand there may be differences in build quality.

by bonsai_spool

4/30/2026 at 1:19:24 AM

Stereotypical image of the doctor is that they carry them over their neck 24/7, so that alone would destroy them pretty quickly.

by dzhiurgis

4/30/2026 at 3:00:57 PM

> Stereotypical image of the doctor is that they carry them over their neck 24/7, so that alone would destroy them pretty quickly.

Why do you assume this? Have you ever used one?

by bonsai_spool

4/29/2026 at 5:54:12 PM

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.”

by sonofhans

4/29/2026 at 6:33:12 PM

The pressure cuff + stethoscope combo is called a sphygmomanometer. It's a pretty fascinating piece of technology: A heartbeat is only audible in the earpiece when the cuff is compressing between someone's systolic and diastolic pressure.

To use it, you get the cuff pressure high enough that you stop hearing a heartbeat in the earpiece. Start releasing pressure slowly. As it comes down, take note of where on the dial you start hearing the heartbeat. That's systolic pressure. Keep listening, and take note of where you stop hearing the heartbeat. That's diastolic pressure.

Using one feels kind of magic.

by Lalabadie

4/29/2026 at 7:00:12 PM

And if you use a mercury sphygmomanometer, you can actually see those pulses appear and then disappear. (It's harder to see them with a gauge-based one.)

by devilbunny

4/29/2026 at 7:46:50 PM

The pulses you see are no substitute for a stethoscope. You see them later and they dissappear sooner than what you hear with a stethoscope.

by M95D

4/29/2026 at 9:23:50 PM

You need a closer eye on it ;)

Or go slower.

I'm an anesthesiologist; we will sometimes use a pulse oximeter below the cuff as a quick estimate. With practice you can estimate SBP to within 5 mm Hg or so, which is more than enough for our needs.

by devilbunny

4/29/2026 at 9:20:53 PM

How about feeling in your arm? I think I can gauge it reasonably accurately.

by dzhiurgis

4/29/2026 at 9:26:17 PM

Palpation BP's are good enough for +/- 10 mm Hg, but not much more, and won't give you diastolic.

by devilbunny

4/29/2026 at 7:17:56 PM

I have a much higher BP when I first go to the office than after I'm sitting in the exam room for a bit.

Usually they call me back to the hallway where they check my weight, then have me sit in a chair and check my temperature, pulse ox and BP, with maybe only a minute sitting down before they do the BP check. My BP is usually in the "hypertension" range there.

But, if they come back to the exam room after I've been sitting in that quiet room for 5 or 10 minutes and check my BP , it's almost always in the "normal" BP range (same as what I see when I check it at home).

Doctor calls it "white coat hypertension", I call it "rushed BP check in the hallway".

by Johnny555

4/30/2026 at 4:29:36 AM

Same. I measure at home and my relaxed systolic is 30-40 lower than the first measurement in their office.

by rhyperior

4/30/2026 at 3:16:27 AM

If you purchase a home BP monitor, it will include instructions on how to take readings, like these:

https://www.heart.org/en/health-topics/high-blood-pressure/u...

Then you will notice when your HCP ignores those instructions, like wrapping the cuff around your shirt-sleeve, or prompting you to talk while the measurement is taken, or allowing you sit with your legs crossed.

BP monitors are often poorly calibrated. The instructions for my home monitors suggest bringing the device into the clinic for calibration, and then the clinician says "we don't do that!"

Manual sphygmomanometer readings won't have an automatic digital readout, and require the human HCP to interpret, announce and record the numbers.

by ButlerianJihad

4/29/2026 at 7:51:02 PM

If the nurse got a reading well outside normal range she should have repeated it to confirm, especially if it was inconsistent with your overall presentation.

by harvey9

4/29/2026 at 5:06:18 PM

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.

by donaltroddyn

4/29/2026 at 6:19:34 PM

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.

by Lalabadie

4/29/2026 at 5:59:30 PM

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.

by boelboel

4/29/2026 at 6:18:28 PM

There does seem to be a difference in quality though. It's much easier to hear the important things with my littman than with the cheap generic stethoscopes I usually find lying around in clinics.

by matheusmoreira

4/29/2026 at 5:14:53 PM

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

by deknos

4/29/2026 at 5:12:20 PM

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.

by elAhmo

4/29/2026 at 5:33:30 PM

It’s funny, most physicians agree that the cheap disposable stethoscopes in isolation rooms are the best, mostly because they are so loud it’s difficult miss anything with them. However, I am not a cardiologist so they may have a different opinion.

by NewsaHackO

4/29/2026 at 6:19:11 PM

I've actually found them pretty terrible. I can't hear subtle findings at all with those. My usual stethoscope is an older-model Littman Cardiology III with stiff rubber and a dual pediatric-adult head. I've had it for over 25 years.

by classichasclass

4/29/2026 at 6:54:00 PM

I guess it's different strokes, because I can definitely hear subtle sounds much easier with them. In fact normal sounds sound like it is going to blow out my ears. The only issue I have is consistency; it's difficult to gauge how much something has changed over time with different stethoscopes, especially pulmonary edema and wheezing.

by NewsaHackO

4/30/2026 at 12:31:35 AM

I would really disagree as a physician that's used a lot of random crap stethoscopes when I don't have one or in an iso room. Those disposable ones are different in what they pick up, some findings are louder others not detectable. Sure I can pick up some stuff like rubs and systolic murmurs but you aren't going to get more subtle findings like diastolic murmurs and fine crackles. Probably a combination of certain frequencies responding and also me being used to mine.

by zeagle

4/29/2026 at 5:19:43 PM

Our one that DIY'd one like one would do a dosing rod in their garage.

by recursivegirth

4/29/2026 at 6:30:21 PM

Well-formed sentence one dosed for make benefit understandability not garage DIY'd one?

Written on ether?

by DoctorOetker

4/29/2026 at 8:24:36 PM

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

by conductr

4/29/2026 at 4:48:59 PM

Is that a lot or a little?

by unsupp0rted

4/29/2026 at 5:03:31 PM

This "recipe" produces them for $5 ... that's 5% of the market price.

by hungryhobbit

4/29/2026 at 5:11:16 PM

Assuming equivalent capabilities and longevity.. I know physicians who have used their "20x too expensive" Littmann for 30 years.

by mikeyouse

4/29/2026 at 5:03:36 PM

À lot

by Agingcoder

4/30/2026 at 4:45:04 AM

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

by copperx

4/30/2026 at 3:14:54 PM

$100? So, like 4 aspirin tablets US hospital billing prices?

by mythrwy

4/29/2026 at 5:25:40 PM

What's the price per use compared to a standard industrial metal one?

by abdullahkhalids

4/30/2026 at 6:04:11 AM

Interesting project.

Feels like the real value here is not beating commercial stethoscopes, but accessibility and local manufacturing. even if performance is slightly worse, being able to produce something “good enough at scale in low-resource environments could still have huge impact.

Curious though has anyone tested consistency across multiple prints? I’d expect variation in material + print quality to affect acoustic performance quite a bit.

by surajguptayc

4/29/2026 at 8:17:59 PM

I seem to remember a major issue re 3d-printing medical things. Early in the pandemic LTT organied an effort to print some PPE face shields for hospitals. It was all rejected. The microscopic holes left in the print material meant it could not be properly sanitized.

A stethoscope touches both patients and providers. This may be a place where smooth non-printed material may be the only sanitary choice.

by sandworm101

4/29/2026 at 4:36:14 PM

No pictures? Missed opportunity. Seems cool though!

by samantha_greene

4/29/2026 at 10:21:56 PM

I can buy cheap ones online from Temu for $3.

However I am comfortable with my Littmann.

Littmann's last for 20 plus years.

by KnuthIsGod

4/30/2026 at 2:40:47 AM

[dead]

by aaron695

4/29/2026 at 4:55:39 PM

Do the design and materials take into account how well it can be sterilized?

by Modified3019

4/29/2026 at 4:59:06 PM

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

by zabzonk

4/29/2026 at 5:02:36 PM

There are disposable, single-patient stethoscopes, but I've seen my Dr do a casual wipe with an alcohol swab often enough...

by jwcacces

4/29/2026 at 5:05:17 PM

I think this is a good point, insofar that how bacterial resistant the stethoscope is relevant. Stethoscopes made of stainless steel are going to beat anything 3d printed by a significant margin.

by xyzzy_plugh

4/29/2026 at 10:08:17 PM

I doubt the diaphragm which actually touches the body, or the flexible tubing of expensive scopes can be sterilized in an autoclave. This diaphragm here is cut from cheap plastic and easily replaceable, the tubing is silicone. I do not believe the flexible tubing on the expensive ones is usually silicone and replacement diaphragms probably cost as much as this whole DIY scope. Metal is resistant to heat, but porous still, so disinfecting with alcohol isn't enough, if you got nasty on it. Never in my life have I seen any doctor pulling a stethoscope from a sterile paper bag. It's likely not as clean as you want it to be.

I believe, in practice you should avoid putting it directly onto the heart, keep a layer of healthy skin in-between. Given the scope of the scope, that may be acceptable, considering the alternative may be direct skin2skin contact with your patient...

But yeah, generally, 3D printed objects are not easy to sanitize properly.Eg. their porosity makes them not safe for repeated food contact. I mean, the glass transition temperature of ABS is 105°, so you could dip it in boiling water, but that's not enough for making it sterile and consequent water inclusions are a welcoming place to start a new family a few hours later for any remaining spores. You could try fractional pasteurization and heat drying, in a pinch, at the end of times.

by jijijijij

4/29/2026 at 6:12:34 PM

It definitely doesn’t help that prints from filament printers are very porous, 100% infill or not. Maybe sealing it with epoxy after printing would help?

by bsza

4/29/2026 at 6:45:01 PM

This seems like another case where the hobby has discovered the 3d printer hammer and forgot that cnc tools (lathe, milling machines) are often better and faster for the job. Or if plastic is what you want injection molding is something you can do on a hobby scale and it is much better (but unlike the others this isn't something you can go from CAD to widget)

by bluGill

4/30/2026 at 4:20:26 AM

In my experience it is very rarely the case that setting up machine tools is faster than 3d printing. And even when it's faster, it's not less trouble. And you have to go and acquire materials in suitable shapes and sizes, and deal with cleaning up chips and offcuts, and deal with deburring and cleaning the part after it's finished.

The 3d printer is always ready and always has material in the right shape. It doesn't make a lot of noise, it doesn't make a lot of waste, the parts come off the machine clean and dry and ready to use. It's really hard to overstate the convenience of 3d printing.

by jstanley

4/29/2026 at 6:14:14 PM

The usual procedure is to wipe with 70% ethyl alcohol.

by matheusmoreira

4/29/2026 at 6:21:08 PM

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

by classichasclass

4/29/2026 at 4:46:30 PM

Are sthethoscopes passive or active devices?

by brcmthrowaway

4/29/2026 at 6:09:59 PM

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.

by matheusmoreira

4/29/2026 at 4:57:25 PM

passive

by kfarr

4/29/2026 at 11:35:50 PM

What we need now is open-source ultrasound devices.

by hereme888

4/30/2026 at 2:31:48 AM

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

by dogmatism

4/30/2026 at 12:32:19 PM

Part of it is this - you get hired by Anthropic making $250k a year. They give you the latest MacBook Pro, a nice office, and a $5 Walmart mouse.

It works. Probably fine.

But it’s weird.

by bombcar

4/30/2026 at 11:03:37 AM

[flagged]

by mfgadv99

4/29/2026 at 6:32:43 PM

[dead]

by onetokeoverthe