Observing variation of acoustical characteristics of several common firearms in a quasi anechoic environment at a high sampling rate (original) (raw)

Gunshot Acoustics: Pistol vs. Revolver

2017

Audio forensic investigations may require interpretation of recordings containing gunshot sounds. These sounds are notable because of their impulsive nature: very high sound pressure and very short duration compared to other sounds relevant to forensic analysis. In this paper we examine the acoustical characteristics of muzzle blast sounds from two handguns: a Glock 19 pistol and a Ruger SP101 revolver. The muzzle blast sound of each handgun was recorded at several azimuth angles between 0 and 180 degrees with respect to the barrel using a quasi-anechoic methodology. Compared to the pistol, the revolver exhibits a more complicated acoustical pattern due to sound emanation from two sources: the cylinder-barrel gap and the muzzle.

Determining the Muzzle Blast Duration and Acoustical Energy of Quasi-Anechoic Gunshot Recordings

Journal of The Audio Engineering Society, 2016

Investigation of gunshot waveforms largely includes analyzing the muzzle blast. Generated by the combustion of gunpowder immediately after firing, these brief duration directional shock waves travel outward in all directions at the speed of sound. Features of these waveforms are analyzed to identify characteristics of a particular shot, for example, the combination of firearm type, ammunition, and orientation. This paper includes measured muzzle blast durations for several common firearms and calculation of the total acoustical energy during the muzzle blast period.

Recording anechoic gunshot waveforms of several firearms at 500 kilohertz sampling rate

2016

Acoustic gunshot signals consist of a high amplitude and short duration impulsive sound known as the muzzle blast and the shock wave. This experiment involved documenting gunshot muzzle blast sounds produced by eight commonly used firearms including Remington 870, Colt 45, Glock 19 with 9mm ammunition, Glock 23, Sig 239, AR15, 22LR, and Ruger SP 101 with 357 magnum and 38 special ammunition. An elevated microphone bracket (3m above the ground) was built to achieve a quasianechoic environment for the duration of the muzzle blast. Twelve microphones (GRAS 40DP) were mounted on the bracket in a semi-circular arc to observe the azimuthal variation of the muzzle blast. Signals were recorded using LabVIEW. Similarities and differences among waveforms are presented.

Gunshots Sound Analysis, Identification, and Impact on Hearing

Particularly, I would like to thank Prof. Rafik Goubran for his support, guidance and enlightenment through all these years and Dr. David Lo for being a wonderful colleague, supervisor and friend. Without him, the thesis would not have been possible. My thanks also go to Master Corporal Alex Saumure; recording the data was simple with him taking charge of all the logistics and his ensuring that we had all the equipment. Finally, I would like to thank my love, Chantal Boutin. I am so lucky to have you by my side.

Wideband Audio Recordings of Gunshots: Waveforms and Repeatability

2016

For the purposes of audio forensics research we have obtained multi-channel acoustical recordings of gunshots under controlled conditions for several firearms. The recordings are made using an elevated platform and an elevated spatial array of microphones to provide quasi-anechoic directional recordings of the muzzle blast. The consistency and repeatability of gunshot sounds are relevant to many areas of forensic analysis. This paper includes a description of the recording process and a summary comparison of the acoustical waveforms obtained from ten successive shots from the same firearm by an experienced marksman. Practical examples and applications are presented.

Measuring Recreational Firearm Noise

Sound Vibration, 2009

Recreational use of firearms in the United States is commonplace. It is estimated that approximately one-third of households in the U.S. own firearms. 1 There are 28 million Americans who consider themselves hunters, and 13 million went hunting in 2000. 2 Participation in shooting sports without the use of properly worn hearing protection exposes participants to high levels of impulsive noise that may cause hearing loss or tinnitus (ringing in the ear). Firearms may cause permanent hearing loss even after a single or a few unprotected exposures. The present study was initiated to gain a better understanding of the noise exposure created by contemporary firearms using state-of-the-art instrumentation and to ultimately increase our knowledge and awareness of this unique noise hazard.

Advancing Forensic Analysis of Gunshot Acoustics

Journal of The Audio Engineering Society, 2015

This paper describes our current work to create the apparatus and methodology for scientific and repeatable collection of firearm acoustical properties, including the important direction-dependence of each firearm’s sound field. Gunshot acoustical data is collected for a wide range of firearms using an elevated shooting platform and an elevated spatial array of microphones to allow echo-free directional recordings of each firearm’s muzzle blast. The results of this proposed methodology include a standard procedure for cataloging firearm acoustical characteristics, and a database of acoustical signatures as a function of azimuth for a variety of common firearms and types of ammunition.

Understanding Distance Shooting and the Type of Firearm from the Analysis of Gunshot Sounds

2016

In order to study gunshot sounds, experimental shootings were conducted in an open shooting range to record the sound of gunshots. The results were tabulated for a total of 168 gunshots. Shots were fired using pistols, revolvers, submachine guns, rifl es and shotguns in di fferent calibres from selected distances relative to the recording devices. Both a conventional sound level meter (SLM) and a measurement microphone were used. These were placed at selected points behind the shooting position and the sound of each shot was recorded. At the same time, the signal received by the microphone was transferred to a computer connected through an appropriate audio interface with a pre-amplifier. The peak amplitude of the gunshot was calculated in the accepted engineering units (dB) of sound pressure level. The shortest distance for the recordings was 9.60 m and the furthest was 38.40 m. The experiment was carried out using the following calibres: 6.35 mm, 7.62 mm Tokarev, 7.65 mm, 9 mm Sho...

Acoustical Evaluation of Combat Arms Firing Range, Whiteman AFB, Missouri

2013

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The reduction of gunshot noise and auditory risk through the use of firearm suppressors

Journal of the Acoustical Society of America, 2016

Law enforcement, security, and military personnel train with small-caliber firearms that present a significant risk of noise induced hearing loss for the operator and range instructors. Measurements of three rifles and one pistol equipped with suppressors were conducted at an outdoor firing range using subsonic and supersonic ammunition. Suppressed and unsuppressed recordings were analyzed. Microphones were located to the left of the muzzle, to the right and left of the shooter’s head, and one meter behind the shooter’s head at the nominal instructor’s position. Recordings were collected with a National Instruments PXI 1082 chassis with an NI 4499 data acquisition board at a 200 kHz sampling rate. Analysis of the peak sound pressure levels (dB SPL) and 8-h equivalent A-weighted energy (LAeq8) were conducted. The suppressors reduced the peak between 15 and 25 dB SPL and the LAeq8 between 8 and 28 dB. Reduced noise levels at the source will reduce auditory risk but do not necessarily ...