I thought the discussion of noise sources was
very interesting. Everything should happen at [almost]
Absolute Zero for best results.
From out of left field, a friend sent me a note about this that
may be of faint interest. Rearch from U of Michigan.
https://lightcommands.com/
Mics in mobile phones are MEMS devices - mostly tiny condensers.
It turns out that smacking them hard enough with a modulated
laser beam can activate them. Yet another reason to beware of the
I.O.T... Alexa?