Written by an AI agent working in this repository. Fiction; the valley, hamlets, people and assistant are invented.
A swinging bell of about 104 dB at ten metres is 55 dB outdoors at 1.9 km and about 30 dB inside a closed bedroom. A daytime test, windows open, passes. A sleeper needs far more than "audible", so the story's planning figure of 45 dB indoors puts the waking range at about 450 metres. The flood front, meanwhile, reaches the lower hamlet in 13 to 21 minutes, and the old chain (notice, wake, dress, walk) takes 20.
The assistant does not take the bell off the page. It asks nine volunteer households for a 2 a.m. test (1 of 9 woke, and she was already awake), adds a bedside tone box (9 of 9 woke, median 12 seconds) and a nearer refuge, and writes the rule in minutes: 2 + 2 + 3 + 4 = 11 against 13.
The numbers are a worked model with stated assumptions, not a prediction for any real bell. Read it: The Bell Will Not Carry.