Sounds from A FireArm

[WALKERs210]

On TV today I saw and listened to an audio clip that is alleged to be the sound of gun fire the time when Brown was shot by a LEO. The sounds were of 5 +/- shots followed after a brief time and then 4 or 5 more shots. On surface that would extremely bad for the officer. Naturally the Audio clip will view and tore apart by many tech's that both side can muster. I know that almost everyone can tell the difference between a rifle or shotgun sound as well with a hand gun. Again it is a given that with today's technology each firearm can and will leave its own fingerprint, firing pin hits, extractor marks and possibly other was. Question I have is even with distortion of distance, walls and who knows what all can a firearm leave it's own distinctive fingerprint in regard to the sounds it produces? My first thought when hearing the clip, well it didn't look good for the officer but then my second though is why after all this time did the man produce this for police, and did he manipulate an construct his own sound bite?

 

[19-3Ben]

I am no expert, but my gut tells me there are a bazillion variables that would play holy heck with the ability to get an "acoustic fingerprint" if you will.
Part of the boom of a gun firing is the sudden pressure release from the muzzle.

The sound of that pressure will be effected by ambient temps, type of powder in the cartridge, the amount of powder that is burned/unburned, and possibly even infinitesimally by the amount of fouling in the barrel as that could potentially change velocity of the cartridge, and possibly many other things I can't even begin to fathom.

My guess is there are just too darn many variables to account for. But I'm not a scientist, not an acoustics expert, and have never thought about it before, so my initial thought on the matter is not exactly gospel!

 

[Tommygunn]

I am no expert, but my gut tells me there are a bazillion variables that would play holy heck with the ability to get an "acoustic fingerprint" if you will.

^^^
True.
Having some minor experience in a previous lifetime in audio recording I can state with minor authority that sudden, loud noises like gunshots can be problematic to record -- even when you actually want to record them.
Everyone has probably watched TV and seen a police drama, western, spy movie, war movie or such and watched a gunfight.
Especially if you go back to older shows, what is being heard on the soundtrack is most likely not the actual sounds of gunfire that were recorded on set during production, but recordings dubbed in during post production from an audio engineer's collection of audio effects. Sounds that are believable as gunfire, not those as I said, recorded at the time, which may have overtaxed the microphone's ability to handle rapid changes in decibel levels.
Now keeping in mind the audio clip in question (I did hear it played by a local radio talk show host) was not even set up to be purposefully recorded, it was many yards distant, outside a window, and recorded by a cheap microphone designed most likely to respond best to the human voice, one may assume a great deal of audio distortion was induced and certain qualities of gunshot sound would be lost.
19-3Ben made a number of good points about this that I won't repeat here.

As to whether the guy who presented it had manipulated it, I don't know. Given all the computerization and advancements in audiology these days it ought to be possible for technicians to determine if the recording is authentic, atleast in terms of being real gunshots.

 

[230RN]

There's also echoes. Don't know what the layout of the area was, though, that would produce shot-like echoes.

Had an instance once where somebody was complaining about ricochets, but I was firing into mud, in the opposite direction, on a river bank, with zero ricochets.

It was actually successive echoes from one of those industrial buildings whose walls were constructed of concrete T-beams, with the "webs" vertical. (I'm sure you've seen buildings like that.)

The shot's single sound was echoed off each web and came back as a "pwaaang," just like a ricochet. Had to demonstrate that effect to the complaining party. He told me he thought the bullets were going right by his head.

Terry

 

[Warp]

Again it is a given that with today's technology each firearm can and will leave its own fingerprint, firing pin hits, extractor marks and possibly other was. Question I have is even with distortion of distance, walls and who knows what all can a firearm leave it's own distinctive fingerprint in regard to the sounds it produces?

Only in CSI and the other bullcrap TV shows/movies, I suspect.

 

[GJSchulze]

Did you listen to the voice? It sounds human, but the cadence is mechanical, so I have my doubts about it. I also wonder if they can even prove it's sound of the actual shooting.

If it is real, how much can it prove other than how many shots were fired and when. It doesn't help you to know what the LEO was thinking.

 

[lxd55]

could it have come off of a tv in the background?
I heard the same bit and the pangs sound too close
not to pay attention and go WHAT? but the voice did not change.
that to me should mean something.

 

[GJSchulze]

The guy claimed that he recorded a chat he was having with someone via his computer. The voice just sounds artificial.

 

[Sam1911]

I think this question has been answered as well as we can legitimately.

We aren't going to wander into arguing the merits of this affair.