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Author Topic: Unusual "how loud" question -- realistic gunfire  (Read 12174 times)

Ed Walters

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Unusual "how loud" question -- realistic gunfire
« on: February 13, 2013, 10:40:15 am »

I am providing sound, both PA and the source material, for a theatrical production that includes Vietnam war scenes and close-range gunfire (AK/M16/M2). The PA can knock the back wall out of the space, it is a non-issue. My issue is how loud is it supposed to be? What is realistic? The director for this show seems to want what I consider excessive but I've never actually heard a .50 up close, or far away, for that matter. I know only subjectively what a 7.62x39 firing sounds like (having run 500 rounds through a Hungarian AKM with a buddy a dozen or so years ago -- no wonder I have a noise notch in my right ear).

What kind of C weighted peak SPL is real, and what is excessive dramatics, and also, where would you set the upper limit, considering the theatre patrons?

Ed Walters
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Art Welter

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Re: Unusual "how loud" question -- realistic gunfire
« Reply #1 on: February 13, 2013, 11:41:58 am »

I am providing sound, both PA and the source material, for a theatrical production that includes Vietnam war scenes and close-range gunfire (AK/M16/M2). The PA can knock the back wall out of the space, it is a non-issue. My issue is how loud is it supposed to be? What is realistic? The director for this show seems to want what I consider excessive but I've never actually heard a .50 up close, or far away, for that matter. I know only subjectively what a 7.62x39 firing sounds like (having run 500 rounds through a Hungarian AKM with a buddy a dozen or so years ago -- no wonder I have a noise notch in my right ear).

What kind of C weighted peak SPL is real, and what is excessive dramatics, and also, where would you set the upper limit, considering the theatre patrons?

Ed Walters
Ed,
A quick google search found this:
http://informahealthcare.com/doi/abs/10.3109/01050399509042203?journalCode=saud

"The peak SPLs at the shooter's ear ranged from 132 dB (miniature rifle) to 183 dB (howitzer). The spectral content of the main part of the acoustic energy was less than 400 Hz (peak 16-100 Hz) for large-caliber weapons and 150-2500 Hz (peak 900-1500 Hz) for small-caliber weapons (rifles). The safe distances from the noise source (less than 140 dB peak SPL) were 50-200 m for large-caliber weapons. Rifle impulses (assault rifle, caliber 7.62) had a peak SPL of 154 dB at a distance of 4 m from the muzzle. The peak SPLs of different explosives ranged from 125 to 185 dB at distances of 10 to 300 m. "

Obviously, these peak SPL readings exceed the capability of your PA, and also are impulse noise. Most standard dB meters would not read the peak reading near as high as this.

Bottom line is anything approaching these levels will cause hearing damage to unprotected ears.

The OSHA limit is 115 dBA slow for 15 minutes, but impulse noise from realistic gunfire could still be well under that limit and still cause damage, especially to those nearest to the loudspeakers.

Bad enough that warfare causes death and hearing damage, does your director want to be responsible for more?

You could suggest a conservative gunfire level, and a slowly decaying ringing sound (usually around 3-4KHz, a couple sine wave tones with some tight reverb works well) in silence afterward to simulate the threshold shift and tinitus we experience after unprotected gunshots.
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Ivan Beaver

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Re: Unusual "how loud" question -- realistic gunfire
« Reply #2 on: February 13, 2013, 11:49:13 am »

When Dr Patronis was doing his military tested years ago (back when the military had a budget they could spend) they took an acre of land and planted B&K 4007's all over it-each one attached to a chart recorder.

The whole idea was to see how loud morters were.  So they fired morters onto the field and recorded the levels-at least up to the point the mics died.

As best they could determine it was somewhere around 165dB (give or take).

So then they built a test chamber to simulate it.

Reproducing that sort of level is NOT easy-or cheap.

I love the home theatre guys who way they want realistic explosions and they are luck if their systems get to 130dB.  That is A LONG way away from reality.
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Jay Barracato

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Re: Re: Unusual "how loud" question -- realistic gunfire
« Reply #3 on: February 13, 2013, 12:06:18 pm »

When Dr Patronis was doing his military tested years ago (back when the military had a budget they could spend) they took an acre of land and planted B&K 4007's all over it-each one attached to a chart recorder.

The whole idea was to see how loud morters were.  So they fired morters onto the field and recorded the levels-at least up to the point the mics died.

As best they could determine it was somewhere around 165dB (give or take).

So then they built a test chamber to simulate it.

Reproducing that sort of level is NOT easy-or cheap.

I love the home theatre guys who way they want realistic explosions and they are luck if their systems get to 130dB.  That is A LONG way away from reality.

I remember watching a three inch thick piece of plexiglass in a bunker flex as a forward observer during a live fire exercise I did in the army.
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Jay Barracato

Ed Walters

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Re: Unusual "how loud" question -- realistic gunfire
« Reply #4 on: February 13, 2013, 12:18:32 pm »

You could suggest a conservative gunfire level, and a slowly decaying ringing sound (usually around 3-4KHz, a couple sine wave tones with some tight reverb works well) in silence afterward to simulate the threshold shift and tinitus we experience after unprotected gunshots.

Now this sounds good. That's what I remember feeling like when firing weapons -- it's loud but the absence of sound/threshold shift and ringing is what I remember more than how loud it was.


It doesn't help any that the dynamic range of pretty much any recorded gunfire I have been able to find is severely compromised and consists mainly of reverb tails.

And it seems if I actually wanted realistic levels, I'd have to con Ivan into loaning me a half-truckfull of JH90's anyway ;-)

Ed
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Tim McCulloch

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Re: Unusual "how loud" question -- realistic gunfire
« Reply #5 on: February 13, 2013, 12:36:43 pm »

I am providing sound, both PA and the source material, for a theatrical production that includes Vietnam war scenes and close-range gunfire (AK/M16/M2). The PA can knock the back wall out of the space, it is a non-issue. My issue is how loud is it supposed to be? What is realistic? The director for this show seems to want what I consider excessive but I've never actually heard a .50 up close, or far away, for that matter. I know only subjectively what a 7.62x39 firing sounds like (having run 500 rounds through a Hungarian AKM with a buddy a dozen or so years ago -- no wonder I have a noise notch in my right ear).

What kind of C weighted peak SPL is real, and what is excessive dramatics, and also, where would you set the upper limit, considering the theatre patrons?

Ed Walters

Politely suggest the director go to an indoor firing range and talk to the range instructor.  He or she will be probably be delighted that anyone from the "arts community" would care about firearms realism.  He or she will also discourage the director from observing live fire without hearing protection. ;)
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John Roberts {JR}

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Re: Unusual "how loud" question -- realistic gunfire
« Reply #6 on: February 13, 2013, 12:52:16 pm »

I like the idea of trying to mimic the threshold shift that occurs.. the dominant sensation after very loud noises is how quiet it suddenly gets, where you don't hear anything around you. This will be difficult in a theater since you can't easily squelch audience noise, unless you artificially pump some surround sound ambient noise into the audience that you can manipulate off.  A constant background ambient sound that suddenly goes completely away might work.  or not... just throwing out ideas.

=====
Loudest noise I recall hearing was in the green machine back in the '70s when they doubled us up on the points of a rifle range to do our annual M-16 qualification, then had us empty the full 18 round clip in rock and roll (full automatic)...  I had bummed some cigaret butts to stick in my ears as plugs, but probably damaged a few cilia that day.. At least the whole group was able to qualify for the year in a few seconds. :-(

Hopefully you will have actual samples of the weapons listed as they can have a distinctive sound signature related to repetition rate in automatic, etc. There will even be differences related to how they are fired (squeezing off small bursts, single shots, etc).

A very LF thumper, like sensaround might help for feel of mortar/explosion realism, without hurting people.
 
JR
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Brad Weber

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Re: Unusual "how loud" question -- realistic gunfire
« Reply #7 on: February 13, 2013, 12:53:01 pm »

Based on some research some years ago when I was doing some work at some of the firing and explosive ranges at FLETC as well as some experience with visitor centers at civil war battlefields, two comments.  First, not only is it difficult to accurately measure such impulsive sounds even with more advanced meters but as others have noted, you would then not want to subject patrons to those levels without hearing protection.

Second, what people think gunfire and explosions sound like and is not necessarily how they actually sound.  I once got into a big argument with a Director over his perception that there was something wrong with the sound system because the cannon fire 'splitting the morn' asunder' did not sound like he expected when both the creator of the sound effect and the re-enactors present all agreed that what they heard was what they expected.  The Director had envisioned a big, low frequency laden 'boom' when what you actually hear when you were as close as was in the video was a much sharper report.
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Riley Casey

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Re: Unusual "how loud" question -- realistic gunfire
« Reply #8 on: February 13, 2013, 01:26:21 pm »

This question doesn't have a technological answer, it has a dramatic answer.  How loud does it need to be to impress the audience - or have  them piss in their pants?  If the director is not getting the effect he wants from mere volume perhaps it's time to think around some corners.  Perhaps some surround speakers with the high pitched whizzing sound of small caliber high velocity rounds such as M16s produced mixed with the lower pitch of the .50 cal.  My first "Ben Burt" moment was trying to create an effective bomb detonation effect for a show involving the USAF band. Spent a week playing with it until we tried a kick drum sample pitched down as far as I thought the subs would survive and mixing that with a couple of good explosion recordings.  It did the trick.  Your sound effects  may be helped with syncing a strobe flash to the rifle reports so that no one sees the muzzle flash so much as sees the ghost of it on the wall or the set.  Review some war movies that have good sound design ( the beach assault and machine gun nest scenes in Saving Pvt Ryan are well done ).    You may find that SPL is not the most important component in creating the desired dramatic effect.

... My issue is how loud is it supposed to be? What is realistic? The director for this show seems to want what I consider excessive ...

Ed Walters

Kevin Maxwell

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Re: Unusual "how loud" question -- realistic gunfire
« Reply #9 on: February 13, 2013, 01:37:14 pm »

You will never run it as loud as it would be in real live that is just too loud. One M16 can easily be over 160dbspl a few feet away from it. How many different guns are supposed to be going off at once?

When everyone is jumping out of their chairs at the sound effect, it is probably too loud. If you actually do it as loud as the director is saying he wants it you will be getting a lot of audience complaints. I also hope your sound system is hung high enough that it isnít right in someoneís face.

I will add that most gunfire sound effects are hardly ever a recording of real raw gunshot. I have edited a few different ones over the years. It depends a lot on what your sound system is capable of and what the expectations are. I have layered multiple sounds together to get some of the ones I have done. It also makes a difference in where it is coming from.

When I did one musical they got a CD (from the rights people) of all of the sound effects including a rather extensive exchange of gunfire. After the fact I realized that it didnít work as well from a timing point of view. And it sounds funny when everyone on stage is no longer moving and there is still gunfire. And when you go to stop the sound effect from playing you sometimes catch it in the middle of a shot.

I usually playback sound effects from a sampler and it enables me to be very precise as to when the sound plays. One rule though is I tell the actors donít actually pull the trigger because the sound of the click of the trigger can be heard by the audience and the timing of that and the shot may be off and it sounds stupid. I tell them just react when you hear the shot.

I had an idea that I know I will never follow thru with so I will share it here. I want to make a prop gun or a device that goes onto a prop that when the trigger is pulled it sends a wireless pulse to a sampler to playback that devices sound effect. It is just a matter of putting together existing parts. Something like a subminiature garage door remote that triggers the sampler. 


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Re: Unusual "how loud" question -- realistic gunfire
¬ę Reply #9 on: February 13, 2013, 01:37:14 pm ¬Ľ


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