In my completely non-expert opinion, I think it would also be a hard dataset to normalize across mic sensitivities/auto gain control/time of day/weather/phone o

In my completely non-expert opinion, I think it would also be a hard dataset to normalize across mic sensitivities/auto gain control/time of day/weather/phone orientation/etc., even if you got a billion people to submit readings. Still, there have been previous attempts at this: 2013: https://www.technologyreview.com/2013/10/22/112756/noise-pollution-maps-crowdsourced-from-smartphone-data/ https://www.technologyreview.com/2013/10/22/112756/noise-pol... 2019, with calibration: https://www.sciencedirect.com/science/article/abs/pii/S0003682X19306772 https://www.sciencedirect.com/science/article/abs/pii/S00036... 2023, iOS only in the USA: https://deohs.washington.edu/noise-across-america-study https://deohs.washington.edu/noise-across-america-study There's a bunch more on Google Scholar, actually.