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.