Zombie Attraction By Noise Calculator

[Vindex]

These are the noise levels we are dealing with in decibals. I assume it requires 50 or more decibels to attact a zombie's attention.

0 decibels: threshold of hearing
50 decibels: rainfall
163 decibels: Rifle firing
166 decibels: Handgun firing
170 decibels: Shotgun firing

At what distance will your gun be heard at 50 decibles or greater? This varies with environmental conditions and effects of other background noise. Maybe 1, maybe 2 miles radius?

You know the noise propagation characteristics of your area of operations better than I do, so you'll have to estimate or experiment.

circle area = PI * (radius) * (radius)
PI = 3.14

Therefore, 1 mile radius = 3.14 square miles, 2 mile radius = 12.57 square miles

Average population density (and therefore zombie density) by state in 1990:
http://www.demographia.com/db-landstatepop.htm

example: Missouri = 74.3 zombies per square mile
If a shotgun can be heard within a 2 mile radius, then 12.57 square miles times 74.3 zombies/sq.mile
= 934 zombies attracted by your shotgun blast at an average location in Missouri.

Go ahead, look up your state population density, estimate the radius your gun or other noise source will be heard at, and calculate how much of a problem you're gonna have.

[randomusername]

Doesn't make sense.

I've been within sight of an outdoor firing range during the day, i mean within a mile and have not been able to hear a single rifle handgun or shotgun, on an open plain, grasses, no woods. Without wind, what does that do to the theory?

[Bender711]

The report from a gun is directional. So if there is nothing of the noise to bounce off of (the range) the you proably wont hear as much as is the were buldings as in an urban enviorment.

thats just my guess.

[JRod]

Directional sound? I.E. the sound perceived a mile away from a firing gun will be greater when the gun is pointed at you. My other problem with this theory lies in the fact that different temperatures and humidity levels will affect how the sound travels through the air. That said, I really like this idea. I just think its going to need more research behind it.

[randomusername]

Directional sound? I.E. the sound perceived a mile away from a firing gun will be greater when the gun is pointed at you. My other problem with this theory lies in the fact that different temperatures and humidity levels will affect how the sound travels through the air. That said, I really like this idea. I just think its going to need more research behind it.

+1

[Vindex]

Research yes, sound propagation is a science in itself.

One lesson I hope can be learned; look at the equation for calculating the area of a circle; it grows exponentially with increasing radius.

Given an average population/zombie density, the zombies you attract grows exponentially with the distance your noise travels.

Notice how rifles give off fewer decibels that pistols and shotguns? And I'll bet 22lr is quietest of all. Of course crossbows are totally silent. In a zombie world the noise of your equipment is a selection criterion.

[randomusername]

Vindex, thats something everyone thinks about. You could almost say just as well that being seen is as deadly as being heard by zombies. The only thing i want to stress is that the noise propagation is not as accurate as the researches would like for it to sound (no pun), and not only that, we could probably only count on zombies in the immediate area to be athreat from noise we make. Zombies outside of 100 yards would probably have trouble getting any better than a 50% cone of direction to hone in on if they only heard 3 shots. let alone they will be competing with building and streets just to get to us.

[Creaux]

Heh, wouldn't have guessed rifles were relatively quietish.

This is a really good point, though, 'cause even if you don't get a thousand zombies coming at you from one blast, we can decrease the range significantly, even take out a few zombies who are in buildings/facing the wrong direction, and still leave you with quite a few zombies. If we want to figure that a gun will make a loud enough report to interest zombies at two thirds of a mile, then we have 3.14159*4/9=1.396 mi.^2, which gives us, at MO's pop. density, ~104 zombies. Still not a ton-o-fun.

[Steev]

population density of my city.. Surrey, BC..


943 people per square kilometer...


I'm scared...

[Steev]

2447 people per square mile... eep...

[EndOfWorld]

I guess this is one situation where you might want to look into the legality of sound suppressors. If they are legal; goody, if they are illegal well your fucked. Sound Suppressors vary in legality from one area to another, so you will have to check the local and state laws yourself. Sound Suppressors tend to be more heavily regulated than the firearm itself in the United States. Even if you do get a sound suppressor they have a limited number of uses before they become trash. Don't do anything illegal, please.



*NOTE: ZS DOES NOT CONDONE ILLEGAL ACTIVITY AND THE OPINION DESCRIBED BY ENDOFWORLD IS MINE ALONE. WE ARE NOT RESPONSIBLE IF YOU DO SOME STUPID SHIT.

[Creaux]

I would say that sound suppressors probably shouldn't be discussed, but I'll leave it to the mods as to if the line has been crossed.

Three notes on this-First, the higher the population density, the more buildings. Buildings work in your favor, for the most part-echoes can confuse the direction that the sound comes from, and buildings can deflect a lot of the initial sound into the air.

Also, urban places are generally going to have more zombies in trapped locations, like a bitten person fleeing into their basement, closet, or car.

Finally, especially in the early stages of the chaos, there will be MUCH more ambient noise in a city, from cars running about/crashing, to other people's gunshots, to glass breaking, and any number of other shit-hits-the-fan noises.

Why am I bringing this up? Don't assume that gunshots won't attract attention, don't assume gunshots will be too unsafe to use. I think this scenario's lesson changes based on what the situation is. If you've (for some on-crack reason) broken back into a city, a while into the PAW, DON'T shoot unless you HAVE to.

This does sort of make one want to look through the "other weapons" forum a bit, doesn't it?

By the way, can anyone give information onto how much caliber changes the decibels of a weapon?

[artyboy]

Colorado isn't that bad. I just have to get out of Denver.

[Vindex]

Population density center of Ottawa where I am: 3258/sq. kilometer

I didn't want to bring up silencers, they've got legality problems here.

It ain't just about the guns; out hiking I hear snowmobiles coming easily a mile off, and chainsaws echo nicely through the hills. These are things one is tempted to use around one's deep woods BOL.

Pi R squared X population density works in these instances as well.

[Gunny]

This is better suited elsewhere:

(Moved to Zed Tactics)

[randomusername]

If it's going to be in the tactics thread line i have to ask:

What kind of survivalist even plans on being stuck in this kind of situation? Most level headed folks that i know on this board have locations set far away from the rest of mankind so that they can go about see, hearing and speaking no evil, if you know what i mean. In my own personal little book, getting into a situation that you have to shoot your way out of, you'd have to go back in time, to un-fuck bad decisions you made in the past just so you have any chance of survival.

That being said, this sound information is something i knew nothing about, and is a stimulating read.

However, nobody in theory should get themselves into a situation where shooting zombies is the best way out. Worst case you should be able to silently dispatch a half dozen, any odds worse than that and it doesn't matter what you do because your in a pickle.

[Creaux]

Well, that's a pretty great thing to be able to say, I'm sure, but I cannot exactly give up great chunks of my life on the small chance that society's catastrophic end is immanent.

I desire an education, as I see it as the best path to personal improvement and satisfaction in my life, so I will stay in Pittsburgh while I get this education. My current plan is to teach after I'm finished, so I will find a place to teach where I am comfortable, which is not in the middle of the countryside. I'm likely to have to deal with moving through populated areas on my way out of a concentration of trouble.

That being said, I agree with you in that a survivalist doesn't pick fights. However, there are situations in which it might become necessary to aggressively use one's firearm; defending a bystander is an example. If someone reading the forum doesn't believe they would do such a thing, then by all means, ignore any discussion of firearms. If it seems like there might be a time in which one might have to use their firearm in a highly populated area, then perhaps keeping track of just who or what you might be alerting is a good idea.

And I'm not sure how you would silently dispose of a half dozen, but that is another thread, ain't it?

[randomusername]

Yes it is.

Just a sidenote; based on police arrests, having two witnesses to a crime instead of one increases conviction rates by 60%. Just a little tiddlywink from my CJ handbook

[Vampire]

I guess with the place as crowded with zombies as it now is with humans now, I don't stand a chance anyway. But even assuming that most people fled the city before the zombies reached your place, it's important to run away after a shootout...

[GoSlash27]

Cheer up: You could be living in New Jersey. Not only are the zombies thick as flies, but they drive IROCs!

[Valarius]

Here is the U.S. 2000 census. Recalculate the figures now.

[Creaux]

Cheer up: You could be living in New Jersey. Not only are the zombies thick as flies, but they drive IROCs!

Heh, someone isn't familiar with my parent's location...At least it's in a decently less-populated part of 'Jersey, with 10ish square miles of hilled-forested park behind the house.

Honestly, Pittsburgh is a pickle, too, 'cause the suburbs are crammed into any available valley for miles around the town. It's tough travelling without going through valleys.

[GoSlash27]

Born 'n' raised in Pittsburgh. Absolutely hideous place to get stuck during a zombocalypse. Perhaps that's why the first training film was shot there.

[hk33k]

A good silencer makes it so someone inside a house does not hear the firearm being discharged outside the front door. Modern silencers technicaly have a finite lifespan, but most shooters will never exceed it(you will wear out the gun first.)
Pat
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