[Eeyore]

Knack wrote:

We currently have one of the quietest ceiling fan models in our bedroom, but
I'm wondering if I can suppress that fan noise even further. However, we
don't want to wear earplugs or noise-cancelling headphones while we sleep.

Just an idea-- Was wondering if it could be possible to somehow make the
sensor and signal processor of one of those noise-canceling headphones (For
example, Panasonic RP-HC500) drive a larger amplifier, which would in turn
power a pair of small cheap PC type speakers. The little speakers could then
be spaced apart above the headboard of our bed.

No. It won't work. You can only ever meaningfully cancel sound over a tiny area
(volume).

Graham