Gunshots recorded in an open field using iPod Touch devices

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.

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.
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.
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.
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.