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Gunshots recorded in an open field using iPod Touch devices

Citation

Cooper, Seth; Shaw, Steven (2020), Gunshots recorded in an open field using iPod Touch devices, Dryad, Dataset, https://doi.org/10.5061/dryad.wm37pvmkc

Abstract

Seven different firearms, including four pistols and three rifles, were fired at least three times each, in order, at a target located at a distance of 45 meters from the shooter, in an open field in Gallatin County, Montana.  Sound was recorded from four different iPod Touch devices.

Methods

The iPod Touch devices were running the software Auphonic Recorder 1.2.1, which was chosen becasue "all default iOS pre-processing is deactivated to get the raw audio signal." The settings used were "Uncompressed PCM Audio," a 48 kHz sample rate, 16-bit precision, and zero attenuation. 

Relative locations of the iPods are shown in the image file rangedim.png, and are described below.

  1. This location represents the sound experienced by someone who is being shot at. This locations should see early arrival of the bullet and impact noise and the muzzle blast, followed by the environmental noise.
  2. This represents an off-axis location which we expect to be identical to the same point symmetrical to the shooting axis. It can also represent a nearby location that is not targeted. Similar readings to Mic. 1 are expected, with the exception of the bullet noise and impact arrival time.
  3. This location involves greater a azimuth angle. It could represent, for example, the location of a nonshooting law enforcement officer and his recording device. At this location, we expect different bullet noise arrival characteristics, potentially larger environmental reflections, and the impact of the bullet hitting the target to be heard after muzzle blast.
  4. This location represents a posterior location. Due to the asymmetric nature of a muzzle blast, reduced amplitude is expected at this location along with a later arrival of the bullet impact noise relative to the muzzle blast.

More information is provided in readme.txt.

Usage Notes

The recordings were started asynchronously, but they can be lined up based on the impulse from the first gunshot. The Matlab file, create_data.m, is provided to pre-process the data for import into Matlab.

The following firearems were discharged in order:

Firearm_ID     Class                 Firearm                                  Ammunition                                              Nominal fps   # of shots

  1. Pistol    SigM11A1,       3.8" bbl                                  124 gr 9mm NATO, STANAG 4090, MEN       1200           4
  2. Pistol    Glock 19,          4" bbl                                     124 gr 9mm NATO, STANAG 4090, MEN       1200           3
  3. Pistol    Colt1911A1,     5" bbl                                      230 gr 45 ACP, Winchester                                835            3
  4. Pistol    Sig 220,            4.2" bbl                                    230 gr 45 ACP, Winchester                               835            3
  5. Rifle     AR-15,              18" bbl, 1-7 twist                     5.56 NATO / M855 62 grain, Lake City           n/a             3
  6. Rifle     308W 24",         Surgeon custom, 1-10 twist    7.62 NATO, Mk 316 MOD 0 equivalent          2600           3
  7. Rifle     308W 18",         Tikka T3, 1-10 twist               7.62 NATO, Mk 316 MOD 0 equivalent          2500           3