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08ravenR1
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Posted: 11/26/2008 12:39:37 PM
I have been reading through these threads and have continually seen that a noise suppressor on a 5.56 will reduce noise approxiamately 30db??

But I have been looking at AAC and all their suppressors state that they remove appoximately 95% of the sound........

What am I missing if an average high powered rifle is around 140-160db's...then 95% of that would be a reduction of between 133db-142db??

Someone show me the light––LOL!!!
87GN
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Posted: 11/26/2008 12:49:17 PM
Basically, 5.56 suppressors reduce the noise to a level at which some may be comfortable without ear pro, and some may not.

I am fine shooting a suppressed 5.56 gun without ear protection.
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Lawman734
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Posted: 11/26/2008 12:55:59 PM
Can you provide a source to where AAC says that their suppressors reduce 95% of the sound? While some of them may be prone to running off at the mouth, I don't think they'd say something that dumb.
Freakinout
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Posted: 11/26/2008 1:12:24 PM
Sound (decibels) is not linear. A suppressed 5.56/223 sounds like a 22lr rifle (without a silencer). It is actually a hair quieter in decibels, but you get the supersonic crack.
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Green0
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Posted: 11/26/2008 2:02:58 PM
[Last Edit: 11/26/2008 2:04:55 PM by Green0]
Originally Posted By Lawman734:
Can you provide a source to where AAC says that their suppressors reduce 95% of the sound? While some of them may be prone to running off at the mouth, I don't think they'd say something that dumb.


I've seen this several times.

97% of muzzle report

The good cans will make the gun quiet enough to shoot without ear protection. Some AAC silencers on some barrel lengths will do that. Sometimes this depends on gas ports and springs and buffers to some extent too.

As far as a percentage of sound- that would be tough for me to quantify. If I had to guess I would say guns get 70-80% quieter, but that's a guess. 97% would seem like a figure I would put at normal conversation levels like 80-85 DB's, and these levels are WAY below bullet flight noise, and theoretically I'm not even sure they are possible, let alone in a sale-able (IE compact) rifle mountable silencer.

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Conqueror
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Posted: 11/26/2008 3:34:56 PM
[Last Edit: 11/26/2008 3:39:08 PM by Conqueror]
Why would you guess? Do you not understand the logarithmic scale on which decibels are measured?

Decibels are counted on a base-10 logarithmic scale. 1dB is measured as a sound intensity of 10^-12 Watts per square meter (or 20 micropascals of sound pressure). From there, everything is calculated as 10 raised to the power of the number of bels (1 bel = 10 decibels) of sound intensity.

If the intensity of 1dB = 10^-12 W/m^2 = "I", then

10dB = 10^1 = 10 x I
20dB = 10^2 = 100 x I
30dB = 10^3 = 1000 x I
40dB = 10^4 = 10000 x I

Etcetera. Thus,

160dB = 10^16 = 10000000000000000 x I, or 10 quadrillion times more intense than a sound of 1dB.

130dB = 10^13 x I, or 99.9% less intense than a 160dB sound. It is perfectly reasonable and correct to say that a 30dB can removes over 95% of sound intensity.

Another way to do this math is that each additional decibel represents a 26% increase in sound intensity. Thus, a 160dB sound is 1.26^30 = 1026 times more intense than a 130dB sound.
Green0
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Posted: 11/26/2008 5:31:40 PM
[Last Edit: 11/26/2008 5:35:05 PM by Green0]
Originally Posted By Conqueror:
Why would you guess? Do you not understand the logarithmic scale on which decibels are measured?

Decibels are counted on a base-10 logarithmic scale. 1dB is measured as a sound intensity of 10^-12 Watts per square meter (or 20 micropascals of sound pressure). From there, everything is calculated as 10 raised to the power of the number of bels (1 bel = 10 decibels) of sound intensity.

If the intensity of 1dB = 10^-12 W/m^2 = "I", then

10dB = 10^1 = 10 x I
20dB = 10^2 = 100 x I
30dB = 10^3 = 1000 x I
40dB = 10^4 = 10000 x I

Etcetera. Thus,

160dB = 10^16 = 10000000000000000 x I, or 10 quadrillion times more intense than a sound of 1dB.

130dB = 10^13 x I, or 99.9% less intense than a 160dB sound. It is perfectly reasonable and correct to say that a 30dB can removes over 95% of sound intensity.

Another way to do this math is that each additional decibel represents a 26% increase in sound intensity. Thus, a 160dB sound is 1.26^30 = 1026 times more intense than a 130dB sound.


Most people don't perceive sounds in the logarithmic scale format. The way sound naturally dampens itself in air, it's not going to be something anyone but a scientist perceives as 97% reduction in sound.

So the logarithmic argument while accurate is probably not going to reflect what people perceive when they hear the device.

In other words stand in an open field, fire an M4, then step 25 meters to the rear and have someone at the original location fire it again, now pick up a suppressed M4, fire it, and the sound intensity will probably feel similar to the unsuppressed at 25 meters. 97%? It likely won't leave the human ear convinced he's actually heard a sound 3% that of the original.


97% is highly likely to give people an unrealistic expectation of what they are going to hear.

This argument is a lot like massive gain numbers in night vision tubes. Do we percieve 50,000 times more light? No. Do we now see something where there was a shadow? yes.
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ORinTX
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Posted: 11/26/2008 5:42:37 PM
Originally Posted By Green0:

In other words stand in an open field, fire an M4, then step 25 meters to the rear and have someone at the original location fire it again, now pick up a suppressed M4, fire it, and the sound intensity will probably feel similar to the unsuppressed at 25 meters.

I think the suppressed gun at the shooter would sound a lot quieter than the unsuppressed gun at 25M.

But yes, describing sound reduction as a percentage is going to confuse those who don't understand the details. For that matter, the same is true when giving dB figures.
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Posted: 11/26/2008 5:55:52 PM
AAC does say 97 percent of the muzzle report. But I believe some of that 97 percent of the report is for the flash as well.

"Civilian sport shooters marvel at the reduction in group size and the ability to witness bullet impact through their optic due to a reduction in recoil of up to 60 percent and a 97 percent reduction in muzzle report." that is quoted directly from AAC's website.

My thoughts is that with shooting supressed it not only reduces the noise but also the flash that may hinder some shooters. Hence the 97 percent reduction in muzzle report.
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Conqueror
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Posted: 11/26/2008 6:07:19 PM
Most people don't perceive sounds in the logarithmic scale format.

Then why even measure in decibels? As long as you are comfortable saying "The bushwhacker is a 32dB can" you should be comfortable with other companies expressing their NSR in a logarithmic fashion. There's really no difference in saying "30dB reduction" vs "97% reduction in sound pressure level." Just different scientific ways of saying the exact same thing.
1928A1
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Posted: 11/26/2008 7:27:06 PM
Originally Posted By Conqueror:
Most people don't perceive sounds in the logarithmic scale format.

Then why even measure in decibels? As long as you are comfortable saying "The bushwhacker is a 32dB can" you should be comfortable with other companies expressing their NSR in a logarithmic fashion. There's really no difference in saying "30dB reduction" vs "97% reduction in sound pressure level." Just different scientific ways of saying the exact same thing.


The problem is that 97% or 99.9% or whatever is quite misleading. Take anyone who has never shot a 556 suppressed and let them fire one suppressed shot and ask them to guess a percentage of an unsuppressed shot. Not ONE will say 97%. Most will probably say 50% or less.

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MEatVt
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Posted: 11/26/2008 8:12:54 PM
Originally Posted By Conqueror:
Why would you guess? Do you not understand the logarithmic scale on which decibels are measured?

Decibels are counted on a base-10 logarithmic scale. 1dB is measured as a sound intensity of 10^-12 Watts per square meter (or 20 micropascals of sound pressure). From there, everything is calculated as 10 raised to the power of the number of bels (1 bel = 10 decibels) of sound intensity.

If the intensity of 1dB = 10^-12 W/m^2 = "I", then

10dB = 10^1 = 10 x I
20dB = 10^2 = 100 x I
30dB = 10^3 = 1000 x I
40dB = 10^4 = 10000 x I

Etcetera. Thus,

160dB = 10^16 = 10000000000000000 x I, or 10 quadrillion times more intense than a sound of 1dB.

130dB = 10^13 x I, or 99.9% less intense than a 160dB sound. It is perfectly reasonable and correct to say that a 30dB can removes over 95% of sound intensity.

Another way to do this math is that each additional decibel represents a 26% increase in sound intensity. Thus, a 160dB sound is 1.26^30 = 1026 times more intense than a 130dB sound.


While accurate this does not fully characterize the situation. Its extremely important to know in what frequencies the sound is carrying its energy, and weather or not a suppressor will dampen the energy in each frequency by an equal amount. I would guess that it does not. This is important because a sound with X energy at A Hz will NOT necessarily be perceived the same as another sound of X energy at B Hz. I have never seen an energy plot of a gunshot with and without a suppressor in the frequency domain, nor do I know the "transfer function" of a human ear.

OP...sorry I cant say much about AACs claim. I always just assume that any number any suppressor manufacture publishes is bullshit. Buy based on what sounds good to you, and on price.
Green0
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Posted: 11/26/2008 8:48:09 PM
[Last Edit: 11/26/2008 8:53:03 PM by Green0]
Originally Posted By 1928A1:
Originally Posted By Conqueror:
Most people don't perceive sounds in the logarithmic scale format.

Then why even measure in decibels? As long as you are comfortable saying "The bushwhacker is a 32dB can" you should be comfortable with other companies expressing their NSR in a logarithmic fashion. There's really no difference in saying "30dB reduction" vs "97% reduction in sound pressure level." Just different scientific ways of saying the exact same thing.


The problem is that 97% or 99.9% or whatever is quite misleading. Take anyone who has never shot a 556 suppressed and let them fire one suppressed shot and ask them to guess a percentage of an unsuppressed shot. Not ONE will say 97%. Most will probably say 50% or less.



That's really what I'm trying to say. I think the DB reduction figure is a lot easier for someone to grasp when they see a unsuppressed SPL of 165, and then see a suppressed one of 134, they can think of it as getting rid of some sound, as opposed to trying to imagine what 97% of sound removed is going to be like.

Then they can compare the 134 SPL to the 122 of a decent .22lr pistol can, and realize it's going to be noisy, but not ear shattering. That way when they fire the first shot they can say, "Cool." Instead of "WTF?"
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Freakinout
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Posted: 11/26/2008 11:51:08 PM
Originally Posted By Green0:
Originally Posted By 1928A1:
Originally Posted By Conqueror:
Most people don't perceive sounds in the logarithmic scale format.

Then why even measure in decibels? As long as you are comfortable saying "The bushwhacker is a 32dB can" you should be comfortable with other companies expressing their NSR in a logarithmic fashion. There's really no difference in saying "30dB reduction" vs "97% reduction in sound pressure level." Just different scientific ways of saying the exact same thing.


The problem is that 97% or 99.9% or whatever is quite misleading. Take anyone who has never shot a 556 suppressed and let them fire one suppressed shot and ask them to guess a percentage of an unsuppressed shot. Not ONE will say 97%. Most will probably say 50% or less.



That's really what I'm trying to say. I think the DB reduction figure is a lot easier for someone to grasp when they see a unsuppressed SPL of 165, and then see a suppressed one of 134, they can think of it as getting rid of some sound, as opposed to trying to imagine what 97% of sound removed is going to be like.

Then they can compare the 134 SPL to the 122 of a decent .22lr pistol can, and realize it's going to be noisy, but not ear shattering. That way when they fire the first shot they can say, "Cool." Instead of "WTF?"


Its easier to understand with DB reduction than a %. Comparing it in terms of .22lr rifles & pistols (unsuppressed) is usually the best way to get it across. I think this is because 22lr (rifle) is the most often shot gun w/o hearing protection
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Mand76
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Posted: 11/27/2008 2:01:27 AM
Originally Posted By Conqueror:
Why would you guess? Do you not understand the logarithmic scale on which decibels are measured?

Decibels are counted on a base-10 logarithmic scale. 1dB is measured as a sound intensity of 10^-12 Watts per square meter (or 20 micropascals of sound pressure). From there, everything is calculated as 10 raised to the power of the number of bels (1 bel = 10 decibels) of sound intensity.

If the intensity of 1dB = 10^-12 W/m^2 = "I", then

10dB = 10^1 = 10 x I
20dB = 10^2 = 100 x I
30dB = 10^3 = 1000 x I
40dB = 10^4 = 10000 x I

Etcetera. Thus,

160dB = 10^16 = 10000000000000000 x I, or 10 quadrillion times more intense than a sound of 1dB.

130dB = 10^13 x I, or 99.9% less intense than a 160dB sound. It is perfectly reasonable and correct to say that a 30dB can removes over 95% of sound intensity.

Another way to do this math is that each additional decibel represents a 26% increase in sound intensity. Thus, a 160dB sound is 1.26^30 = 1026 times more intense than a 130dB sound.


Mand76
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Posted: 11/27/2008 2:09:06 AM
[Last Edit: 11/27/2008 2:10:58 AM by Mand76]
Originally Posted By Conqueror:
Most people don't perceive sounds in the logarithmic scale format.

Then why even measure in decibels? As long as you are comfortable saying "The bushwhacker is a 32dB can" you should be comfortable with other companies expressing their NSR in a logarithmic fashion. There's really no difference in saying "30dB reduction" vs "97% reduction in sound pressure level." Just different scientific ways of saying the exact same thing.


You are such a troll...

Foolishly supporting AAC's CRAP with your own idiotic comments AND belittling Green0's statements with BS is just asinine. Give it up, would you please?

AAC LOVES to use misleading figures, even if somehow they are tied to reality. Opening your mouth about things such as this is just proving to some people what a lot of us already know...

32ACP
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Posted: 11/27/2008 7:24:44 AM
08ravenR1,

When I shot my Gemtech G5 from my 16" Bushie the first time, I was standing next to a guy with a lever .22LR that had a shot barrel (don't know the brand––it was an 1950s-made .22LR)––they range guys all said the .22LR was a little louder than the AR.

If you're expecting 'Hollywood quiet" you'll be very disappointed. As has been already said––most folks shooting say that it sounds like 50% of the noise is gone––not 97%.

I think you have to consider––what are you looking for? If you need REEEAAAL quiet, a .22LR may be what you want. OTOH, my AAC Evo9 Glock17 is quiet enough to shoot without ear protection––maybe a 9mm carbine would be more of what you're looking for? Not sure.

Conqueror
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Posted: 11/27/2008 9:04:28 AM
Originally Posted By Mand76:Foolishly supporting AAC's CRAP with your own idiotic comments AND belittling Green0's statements with BS is just asinine.

Would you care to point out what part of my post was BS? Every bit of it is true and easily verifiable to anyone who understands math above a 10th grade level.

Anyone who actually understands what decibels are will hear "30dB reduction" and immediately know that it's a 10^3 or 99.9% reduction in intensity. What you are basically saying is "most of us are too stupid to conceptualize this, so we prefer our information in a form that caters to us."
Tuukka
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Posted: 11/27/2008 9:10:40 AM
Originally Posted By 1928A1:
Originally Posted By Conqueror:
Most people don't perceive sounds in the logarithmic scale format.

Then why even measure in decibels? As long as you are comfortable saying "The bushwhacker is a 32dB can" you should be comfortable with other companies expressing their NSR in a logarithmic fashion. There's really no difference in saying "30dB reduction" vs "97% reduction in sound pressure level." Just different scientific ways of saying the exact same thing.


The problem is that 97% or 99.9% or whatever is quite misleading. Take anyone who has never shot a 556 suppressed and let them fire one suppressed shot and ask them to guess a percentage of an unsuppressed shot. Not ONE will say 97%. Most will probably say 50% or less.



I concur,

My opinion is that for your average shooter or hunter, it is not the best way to convey the effectiveness of the suppressor.

Mentioning the sound pressure level of the weapon without a suppressor, hearing damage / pain threshold and what the suppressed SPL will be, will give a better sense of the effectiveness.

Conqueror
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Posted: 11/27/2008 9:11:58 AM
Originally Posted By Green0:I think the DB reduction figure is a lot easier for someone to grasp when they see a unsuppressed SPL of 165, and then see a suppressed one of 134, they can think of it as getting rid of some sound, as opposed to trying to imagine what 97% of sound removed is going to be like.

Again, you're saying "most people are clueless about what decibels are, so let's cater to them."

I agree that 95% of the American public are dipshits and have no clue what a logarithm is or how decibels work. That doesn't mean I get pissy at AAC for saying something that is perfectly accurate, and verifiable by anyone with a calculator. 90% of people don't know what a "BTU" is, but they still want a furnace with lots of them.
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Posted: 11/27/2008 9:19:20 AM
I had a HALO on a 16" barrel. It was like shooting a .22lr or .22mag, sound wise. I could not shoot without hearing protection. I was shooting at an outdoor range with concrete over hangs, so the sound was there. With Subsonic ammo it was better.

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Posted: 11/27/2008 10:48:37 AM
Be thankfull and knock the crap off.
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Mand76
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Posted: 11/27/2008 12:53:20 PM
Sorry Matt I didn't mean to get crappy but some of those statements are just insulting- I don't know who learned decibel logarithms in 10th grade...

I'm surprised you still needed hearing protection with the Halo- it was definitely the concrete around you- more than likely, you'd have that problem with any supersonic ammo through a suppressor. When I shoot outside, you hear the pfffft of the gun and THEN you get the crack a split second later when it echoes off of the ground and berms...

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Posted: 11/27/2008 12:59:56 PM
Originally Posted By Mand76:
I don't know who learned decibel logarithms in 10th grade...

Lots of people did.

You could make the same statements without resorting to name calling and insulting tactics. You're just so damn angry.
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DevL
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Posted: 11/27/2008 2:06:28 PM
[Last Edit: 11/27/2008 2:08:36 PM by DevL]
Hmmm... I never heard the 97% reduction figure untill just now and I knew that it was based off a logarithmic difference as soon as I read it. Anyone with enough knowledge to even consider db figures probably knows this. I dont see how this is misleading at all. Just saying a suppressor reduces SPL a specific db figure is JUST as misleading. It depends on ammo, barrel length, weapon used, etc. Saying a silencer reduces SPL 40db some odd, unstandardised figure downrange is more misleading.

If a marketing person can say something is 100% stronger or the other product is only 50% as strong, the larger figure is what they will pick.

AAC's figure is correct. I guess they stated the factual figures. I dont see whats so horrible about that.
DevL
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Posted: 11/27/2008 2:07:53 PM
Originally Posted By 08ravenR1:
I have been reading through these threads and have continually seen that a noise suppressor on a 5.56 will reduce noise approxiamately 30db??

But I have been looking at AAC and all their suppressors state that they remove appoximately 95% of the sound........

What am I missing if an average high powered rifle is around 140-160db's...then 95% of that would be a reduction of between 133db-142db??

Someone show me the light––LOL!!!



Yeah, you have it right. You have already seen the light. Your figures are about what 5.56 silencers do. I guess I dont understand why this turned into a pissing match thread.
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