[RisingFusion]

I think it was referring to Electrical network frequency analysis, which is to find the time that the recording was made. It compares small changes in mains hum frequency to historic records of the changes. I am not sure how it is in the US, but the UK grid has a single frequency over the network so it wouldn't work for finding the location.

[teruakohatu]

The propagation of waves is very fast, but wouldn't distance from multiple large sources or sinks fluctuate the frequency just slightly based on distance?

[torified]

Distance doesn't change frequency, only velocity. Doppler effect.