There are some piano tuners I've found who are a bit on the spectrum, who believe they can tune a piano in a way that no digital device can replicate. I'm skeptical, and would like to see how this method holds up against one of these savants.
Fun analysis experiments like this are why I made the free demo app (it runs on iPhone/iPad/Mac):
Impressive. Thanks for the pointer.
No inherent limitation of the technique, the resonators can be tuned to much lower frequencies. But indeed you‘ll need a better mic than the iphone’s to get frequencies below 50Hz iirc… too bad - the watermelon ripeness checker could be a really cool app :-)
Let me know if you update your app or make a watermelon version.