Comment by hex4def6 | Hacker News Reader

Comment by hex4def6 | Hacker News Reader

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.

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!

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.

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

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...

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.

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

> 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.

Check "An in vitro acoustic analysis and comparison of popular stethoscopes" [0]. There's a $8 stethoscope - Mabis Spectrum, with great performance, according to this study.

[0]: https://pmc.ncbi.nlm.nih.gov/articles/PMC6339642/

Hat tip! I found their Amazon page here: https://www.amazon.com/stores/Mabis/page/7C938264-7E20-4C0A-...

Very cheap, indeed.

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.

They don't come in "pink rose satin finish"

https://www.amazon.com/Littmann-Stethoscope-6159C-Flexibilit...

metanym

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

  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

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.

Thanks!

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

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.

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?

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.

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.

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.

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.

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.

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.

> 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.

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

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

Reply on news.ycombinator.com