Sigourney, IA Noise Levels
Sigourney, IA: what the federal noise map shows
Sigourney, IA is one of the places where the federal model has nothing to report above its 45 dB(A) floor, on any of the three sources.
That figure is sampled at one coordinate, the Census Bureau's own internal point for Sigourney, not a street-by-street survey of the whole place.
Where Sigourney ranks
There's no loudness rank for Sigourney: it's one of 8,515 places nationally where BTS's model measures nothing above its 45 dB(A) floor. About 1,974 people live there, making it the 7,733th largest place in this dataset.
Your street may differ from Sigourney's reading
For a single house or lot in Sigourney rather than the town-wide figure above, BTS's own map is the same free source, queried directly.
More on how this number was built
For exactly which federal dataset feeds Sigourney's figure, see the methodology guide. The guide to reading a quiet result explains what "no measurable noise" actually means at Sigourney.