I shot these real time analyses of my living room for you last night and this morning on a quick and dirty RTA I have on my iPhone. Last night I left the ceiling fan on but it is a nice Hunter hung nine feet up, halfway between floor and ceiling. I hung and balanced it myself and from my location the slow speed it was set to is below the threshold of hearing. This morning I turned off the fan and shot the RTA again. The times are at the top of each, with last night's on the left. Pardon the slight scale offset due to me fooling with the zoom.
The conditions: my house is on a boulevard in a suburb and is located about a half mile from a major interstate highway. I waited until there wasn't a car passing and the heat pump had cycled off. The app says it is self-calibrating to your particular iPhone model's mic response but not to the specific mic. I noticed that whenever I attempted to pause the screen for a screen shot by pressing the on-screen icon the low-end tilted up and the overall noise level showed about 3-4db higher, presumably from handling noise. My guitar callus made it hard to activate the pause!
The dogs and I held our collective breaths. Sort of. The 5db of reduced noise from turning off the fan, mostly showing in the low end, can be fixed with a mic's roll off. I could hear power equipment in the next neighborhood and the flow noise from the interstate highway that are reflected in the low end of the graph. What strikes me is how similar the noise is between night and morning.
Bob