gunshot noise distance


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alexl650
October 7, 2006, 11:52 AM
does anybody know the approxmite distance that the sound of a gunshot (rifle or pistol) is no longer audible. how far away would you have to be for someone not to hear a gunshot. i know this would depend on certain factors. elevation changes, presence of sound buffers, trees, buildings, etc. if anyone has any knowledge of this please let me know. thank you

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Third_Rail
October 7, 2006, 12:07 PM
What caliber? Barrel length? Ported? Flash hider?


As you can see, there are a lot of variables.

alexl650
October 7, 2006, 01:02 PM
9mm 5 inch barrel no ports, no flash hider
7.62 x 39 16 inch barrel no ports no flash hider
.45 5 inch barrel no ports no flash hider

hjrocket
October 7, 2006, 01:24 PM
Too many variables to give even an approximation. IE: From my house to my gun club, the slant range is 6.7 miles,(and mutually visible) the club is 520 ft higher, and i can hear rifle, pistol and sporting clays shots under all Wx conditions from my deck outside. Not obtrusive, but I can hear the shooting. The airport (mutually visible) is 19.8 miles away and 600 feet lower and under certain conditions of Wx, aircraft taking off are quite audible.

alexl650
October 7, 2006, 02:13 PM
i am not looking neccesarily looking for a specific answer. i guess if someone lives less than 15 miles from a range and can't hear it that might be useful, anyway thanks for the input.

Byron Quick
October 7, 2006, 02:19 PM
During the Battle of Gettysburg, some towns over a hundred miles away heard the cannon fire. General Meade, ten miles to the south, did not hear the cannon fire.

The distance gun fire can be heard is dependent on too many factors to give even a rough estimate. The same report can be heard for many times the distance in one direction than it is heard in another direction. Depending on wind directions, topography, temperature and pressure differences, etc.

The answer is indeterminate.

What can be heard one day from a particular distance under prevailing conditions might not be heard the next day under differing conditions...or even a few minutes later.

PlayboyPenguin
October 7, 2006, 02:21 PM
I hope you are not asking this just to know how far out of town you are going to have to drive your spouse before noone will hear the gunshots. :eek: :D

alexl650
October 7, 2006, 02:54 PM
no, that is not the case, just trying to find a good place for target practice where no one will bother me. in canada they don't like when people use there guns for anything other than hunting, they don't even like that much. anyway people around here bitch and call the police when they hear more than one shot, even in the forest (can't stand the local RC's). the ranges are even less tolerable. anyway, i geuss it is totally dependant on a lot of variables. thanks anyway for the response

bluecowdawg
October 7, 2006, 03:07 PM
I hope i aint out of line here but i dont think it good to answer a ? like that to someone who only has 4 posts.:uhoh: Also i have noticed on this board and others that i visit a lot of new people joining lately. They seem to ask a lot of odd questions and dont post much.I know this makes me look kinda like a hipocrit cause i dont post much either ,but i have been a member for a long time.

Oh well I dont know,just an observation:scrutiny:

hso
October 7, 2006, 03:09 PM
There's no way to answer the question.

Not only do you have all the variables associated with weapon and ammunition specifications you have to contend with atmospheric conditions, vegetation and terrain.

Clear, calm, crisp day with no trees and flat ground you can hear for miles and miles. Humid, windy, trees on hilly terrain you'd probably halve that.

BTW, Welcome to THR! How'd you find us?

Lucky
October 7, 2006, 05:14 PM
What about taking the muzzle volume and then working out a distance required to reach 10 or 15 dB volume? So if a volume is 100db at the muzzle, and you go 100m, it will be 4/3.pi.50^3=8,333,333 1/2 that is 4,166,666m3. (half because we don't count ground)

If you assume muzzle volume to be in a sphere of 1/2 1m3, that'd be 0.5m3.

Divide the far distance by the close one gives you 8,333,333, so you'd assume the sound is that many times quieter?

Just count backwards multiplying by 10 to go down in dB, so to go down 10,000,000 you go 7 steps, (10^7), and that's 80. 90dB would be 1,000,000.

So, umm, 8million times quieter than 150dB would be somewhere between 80 and 90dB, closer to 80 than 90. Maybe 82 or 83.

And you could work it like that to figure out where it would be 15dB.


Just a rather large WAG though. If anyone can test this it would be awesome.



Of course that would be on the plains, and assume sound spreads out evenly, but those are trifles.http://guns.connect.fi/rs/dirdiagr.GIF

Lucky
October 7, 2006, 11:10 PM
Maybe it would be better to make a new post instead of editing en masse.

So if the muzzle noise is 150dB, compared to silence at 0dB and the smallest sound you can hear at 15dB, then it's a matter of finding the distance where you hit 10 and 20dB and figure 15 is in the middle.

And instead of taking half the sphere as the volume, maybe it's better to use 1/6, a third of the top half, since that's what the picture seems to show anyway.

So 1/6*4/3*3.14=0.697; so 0.697*X^3=Y{m3}.

And is X=1 when dB=150, then you can work from there. I think.

So at 11.3km you'd have 1,005,699,209,000m3 which is 120dB difference, so the sound would be around 30db.
And at 25km you'd have 10,890,625,000,000m3 which would be 130dB difference, putting estimated sound at 20dB.

So 20dB is just barely louder than a whisper, heck so is 30. For all intents both sounds are near inaudible. So I'd esimate that at 11 and 25km on a flat plain that's how you'd hear a gunshot that was 150db at the muzzle, and the gun was firing at you. If the gun wasn't firing at you it'd be closer. You could look at the diagram above and estimate the difference, and then punch in the numbers. But I wasn't using the proper Db log formula, just punching numbers, so you could get it more precise. And I made the whole formula up, too, so that could be a problem.

Double Naught Spy
October 8, 2006, 07:50 PM
We have a piece of property just shy of a mile from the house with a ravine in it where we shoot. The ravine area is treed with mature oaks that provide great shade and you would think would provide sound suppression. I can listen to my wife shoot her 9mm Kahr while in the ravine from nearly a mile away. However, there is a neighbor in between who doesn't hear the noise of our shooting. So last time my wife shot, I pulled in his driveway and listened. Nada. He is about half the distance, but the sound bypasses his place.

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