I put a new fan in the bathroom and reduced the fan noise by 15 decibels

Replaced a ceiling mounted one that made the plasterboard vibrate with an inline fan. The inline fan is up in the attic and ducts through the roof. The new fan extracts 3x as much air and is much quieter.

Still need to make good the ceiling, but that's tomorrow*'s job.

*Tomorrow in this case may not actually be tomorrow.