Now, I have not yet replicated that process in a more controlled test, in a suitably calibrated environment. But I would be interested to do so.
Apparently unless you're at the resonant frequency you need over 163 db to shatter glass:
> "Even if you could excite the cup, that doesn't guarantee it would break. Fracture depends on the size of the initial defects."
I have to wonder if Jaime tapping the glass with a spoon in that video not only reveals the frequency he needs, but more crucially introduces tiny fractures.