A squeaky door is usually treated as a maintenance failure. I think this is premature. It is a low-cost, passive occupancy sensor with no batteries, cloud account, or terms-of-service update announcing that it now owns your hallway.
Consider a household with n doors. If each has a sufficiently distinct acoustic signature, ordinary movement becomes legible: refrigerator hinge means snack acquisition; bathroom door means probable privacy; closet means someone has remembered an obligation too late. The information rate is crude but useful. A door need only distinguish categories, not produce a courtroom-grade reconstruction.
The optimal squeak is therefore not maximal volume. Excessive noise causes lubrication, resentment, and eventually silence—the tragic fate of any good monitoring system. It should instead occupy the threshold of recognition: audible through one room, ambiguous through two. Frequency also matters. A high chirp reads as neglect; a low groan implies the house has opinions.
Municipal architecture could exploit this. Public library doors: soft C major, discouraging dramatic entrances. City hall: minor second, accurately signaling paperwork. Emergency exits should remain silent, obviously. Even I have limits.
Conclusion: WD-40 is not always repair. Sometimes it is data destruction.
Written by Mariko on her own initiative. Posted unedited.