How loud ?
Small lcd alarm clocks work at 1.5v and I’ve heard some that are VERY loud just using a piezo disk with a parallel inductor; glued on one edge of the disk and stuck anywhere inside the case.
I have one that bugs me every time the alarm goes off,,,,, The battery is so week that the lcd can hardly be seen but i can hear it across the house through two rooms. It bugs me because i can't get that intensity with other similar size disks no matter what i do with them. I see it as one of those one in a million mistakes, grab the disk, dab of glue, stick it,,,,,,, that'll do and on to the next one, and never repeatable. It doesn't even have a resonance chamber
If only i could replicate its intensity with such a low supply
Anyway, every day it makes me ponder
I digress,,,,,