Applications of math: current events

[Claudio L.]

(10-14-2017 05:31 PM)DrD Wrote:  With many cell phones acting as microphones, the "basic setup" mentioned in the wik,i that pier4r provided, is pretty well covered. I think a mathematical analysis, including doppler corrections could compensate for not having ideally located microphones. Sound software such as sound forge, would be useful to get the timing just right, as well as remove artifacts that might be interference. I guess there was a helicopter in the area at the time, so the rotor blades might add a layer of confusion there, as well.

Yes, if you could get the exact location of each recording device, and if you could time-sync the recordings. In the real case, many of the phones were moving, as people were running away, which makes it much harder to pinpoint where they are at any given time. Also, the time of the recording would have to be synchronized somehow between devices, perhaps looking at a frame of the video with the same event happening, but it would be really hard to get 2 or 3 valid recordings to use (with well-defined location, not moving and where you can time-sync the signals).
You also need to know where the bullets were hitting. Different recordings might be picking up bullets going to one or the other side of the arena. We are talking potentially 91m (100 yds) distance between the bullet-hitting point from one end to the other of the place.
Once you get that good data (if it exists), then you can start doing numbers and making conclusions using procedures like the ones Pier linked. Without complete and consistent data it's nearly impossible to draw any (meaningful) conclusions. Certainly not by doing simple arithmetic like this guy did.