An ER could easily triage people into an urgent care wing of the hospital, but hospitals don't have those. Because they don't have any incentive to provide anything resembling cost effective care.
The wave would be focused by the transducer (analog of a lens) so that the energy flux is highest at the focal point and presumably low enough not to cavitate outside the focal area. I.e. magnifying glass and the sun kinda thing.
I think the way it works is you have sound from multiple sources, and you time the sound waves so that the peaks and troughs all hit the targeted area at the same time. Each individual 'beam' is harmless, but at the point of intersection they add up and can do damage.
I was just thinking the inference cost could be reduced by making hardware with less error correction in specific areas to get higher density, and let the NN work around the limitations.
Happened to me before, I thought it was a generator running at a construction site down the street. It wasn't that long ago but I don't recall exactly when it stopped or if anything correlated.
I used to think that the generators were running at the bank call center 1/4 mile away. I only heard it when it was very quiet, any noise at all and the low droning disappeared.
I took more vitamins during the early days of the pandemic and magically the generators stopped running.