Researchers from Department of Electrical and Computer Engineering at Montana State University in Bozeman constructed a semicircular aluminum frame with 12 evenly spaced microphones in order to analyze the sound of gunshots from different guns.
In general, there are several ways a gun can be linked to a crime: striations on a bullet, gunpowder residue, trajectory, ricochet and bullet holes, hidden fingerprints, firing pin impressions and bullet damage to tissue. But these researchers believe that acoustic gunshot sound analysis could provide even more information on the type of gun used which can help forensics teams.
To the naked ear, most gunshots seem to sound alike, but researchers say each firearm has a distinctive signal. The idea from the research was to determine through sound waves how to distinguish between the sound pattern a 12-gauge shotgun makes versus a .38 Special handgun in order to help solve crimes.
The team is is building a database of sounds which are made by 20 different guns to chart out differences in the sound waves. The researchers say these audio recordings of gunshots can provide information about the gun location with respect to the microphone(s), the speed and trajectory of the projectile and in some cases the type of firearm and ammunition.
Dr. Robert Maher, Professor and Department head of Electrical & Computer Engineering and Affiliate Professor of Music Technology, Montana State University, says he hopes that one day investigators could use the information to determine what kind of guns were fired at a crime scene.
“Of course, most crime scene recordings aren’t high quality — they often come from cellphones or surveillance systems,” said Maher. “But we are analyzing and comparing those recordings with ones made in our outdoor “lab” to figure out which aspects of crime scene audio we can analyze.”