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.

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.

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.

(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?

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.

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

However I am comfortable with my Littmann.

Littmann's last for 20 plus years.

It works. Probably fine.

But it’s weird.