Can someone explain why the sound meter readings at the muzzle and the ear are different, and within that - why the muzzle readings are typically lower than the ear readings (even on bolt actions).
TIA
TIA
Suppressors Ear vs Muzzle DB Discrepancies?
- Thread starter Mo_Zam_Beek
- Start date
Re: Ear vs Muzzle DB Discrepancies?
Mo,
Not enough information. Brake? Can? Crown?
Mo,
Not enough information. Brake? Can? Crown?
Re: Ear vs Muzzle DB Discrepancies?
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: RollingThunder51</div><div class="ubbcode-body">Mo,
Not enough information. Brake? Can? Crown? </div></div>
I think what he might be asking is why are the reading different at all for any given platform. I am pretty sure that the readings being taken form the two different physical locations (shooter ear vs. 1 meter to the side of the muzzle) is the reason. Would you concur?
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: RollingThunder51</div><div class="ubbcode-body">Mo,
Not enough information. Brake? Can? Crown? </div></div>
I think what he might be asking is why are the reading different at all for any given platform. I am pretty sure that the readings being taken form the two different physical locations (shooter ear vs. 1 meter to the side of the muzzle) is the reason. Would you concur?
Re: Ear vs Muzzle DB Discrepancies?
RT / DPD: yesterday I got to looking at a major dealer's sound testing numbers related to several pistol and .22 cans as well as the sound testing for action noise only.
Generally speaking I noted a difference between the muzzle reading (typically lower) than the 'at ear' reading. Now I get the fact that this can in some cases be attributable to the noise of the action (as well as the testing equipment and the manner the test was conducted); however even when a bolt action .22 was tested this seemed to generally be the case.
I am wondering if there is a rhyme to the reason other than testing and equipment?
TIA
RT / DPD: yesterday I got to looking at a major dealer's sound testing numbers related to several pistol and .22 cans as well as the sound testing for action noise only.
Generally speaking I noted a difference between the muzzle reading (typically lower) than the 'at ear' reading. Now I get the fact that this can in some cases be attributable to the noise of the action (as well as the testing equipment and the manner the test was conducted); however even when a bolt action .22 was tested this seemed to generally be the case.
I am wondering if there is a rhyme to the reason other than testing and equipment?
TIA
Re: Ear vs Muzzle DB Discrepancies?
Got it now many thanks (he says while buckling his seat belt)
First we separate out any thought of SS bullet flight's contribution.
Within the course of perhaps the first 100 feet, we would see the muzzle blast being significantly louder than the supersonic flight signature. Farther down range, when the bullet is significantly faster than the speed of sound, the super sonic flight signature will be the predominant artifact. The creation of the ss signature shock wave is like a wake of a boat, diminishing with the inverse square of the distance from propagation. At the rifle we concern ourselves solely with the metering of the muzzle blast, or with a can, its resulting suppressed blast.....
We can see that the shock wave from muzzle blast of an AK expands in a spherical shape quite different from that of the bullet signature. Here we can see the unimpeded shock wave inline with discharge, and the somewhat weaker dB readings (when compared to the freely generated shock wave in front of the can) caused in part by the presence of the can/rifle surface structure. The muzzle blast actually deteriorates in an inverse cube of the distance traveled from the point where the gases trapped behind the bullet finally escape around it and go supersonic in the open atmosphere.
Think of it this way.
In the barrel the air found in front of the yet to be discharged bullet must be expelled. There is sound generated there, as a pop as it is slammed into the outside environment. This is prior to FRP (first round pop) as the propellant volatils are trapped behind the bullet at this point. Then we have the bullet's exit, followed by those gases we just spoke about hitting the additional O2 in the can, or potential FRP. Then:
The split, the creation of the bullet flight signature and the release as super acceleration of the gas propellant.
I've always wondered if the creation of the ss signature pathway creates an environment that contributes to a more efficient dispersion of the muzzle blast down range. I honestly do not know. But, if it does, that could account for the spherical blast distortion as seen above.
I'll throw this out and see if I can even make sense of it. Tip of the hat to Mr. Boyd.
A tonic for the sleep deprived
http://www.nvtech.com.au/ProjPast/SmallArmsSilencer/Silencer-1-Intro.html
Got it now many thanks (he says while buckling his seat belt)
First we separate out any thought of SS bullet flight's contribution.
Within the course of perhaps the first 100 feet, we would see the muzzle blast being significantly louder than the supersonic flight signature. Farther down range, when the bullet is significantly faster than the speed of sound, the super sonic flight signature will be the predominant artifact. The creation of the ss signature shock wave is like a wake of a boat, diminishing with the inverse square of the distance from propagation. At the rifle we concern ourselves solely with the metering of the muzzle blast, or with a can, its resulting suppressed blast.....
We can see that the shock wave from muzzle blast of an AK expands in a spherical shape quite different from that of the bullet signature. Here we can see the unimpeded shock wave inline with discharge, and the somewhat weaker dB readings (when compared to the freely generated shock wave in front of the can) caused in part by the presence of the can/rifle surface structure. The muzzle blast actually deteriorates in an inverse cube of the distance traveled from the point where the gases trapped behind the bullet finally escape around it and go supersonic in the open atmosphere.
Think of it this way.
In the barrel the air found in front of the yet to be discharged bullet must be expelled. There is sound generated there, as a pop as it is slammed into the outside environment. This is prior to FRP (first round pop) as the propellant volatils are trapped behind the bullet at this point. Then we have the bullet's exit, followed by those gases we just spoke about hitting the additional O2 in the can, or potential FRP. Then:
The split, the creation of the bullet flight signature and the release as super acceleration of the gas propellant.
I've always wondered if the creation of the ss signature pathway creates an environment that contributes to a more efficient dispersion of the muzzle blast down range. I honestly do not know. But, if it does, that could account for the spherical blast distortion as seen above.
I'll throw this out and see if I can even make sense of it. Tip of the hat to Mr. Boyd.
A tonic for the sleep deprived
http://www.nvtech.com.au/ProjPast/SmallArmsSilencer/Silencer-1-Intro.html
Re: Ear vs Muzzle DB Discrepancies?
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: RollingThunder51</div><div class="ubbcode-body">
A tonic for the sleep deprived
http://www.nvtech.com.au/ProjPast/SmallArmsSilencer/Silencer-1-Intro.html
</div></div>
For anyone interested in the general topic of sound suppression that is worth the read.
Thank you RT.
Good luck
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: RollingThunder51</div><div class="ubbcode-body">
A tonic for the sleep deprived
http://www.nvtech.com.au/ProjPast/SmallArmsSilencer/Silencer-1-Intro.html
</div></div>
For anyone interested in the general topic of sound suppression that is worth the read.
Thank you RT.
Good luck
Re: Ear vs Muzzle DB Discrepancies?
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: RollingThunder51</div><div class="ubbcode-body">
</div></div>
Based on what I just read (assuming I understood it) having sound data plotted 360 degrees with DB numbers and distance points would be a much more beneficial in making a decision as to which sound suppressor to get based on sound reduction alone.
Providing I understood the article - there is a finite amount of sound as the result of the shot. Mechanical manipulation of the pressure (gasses) creates a geographic dispersion of sound. The more that sound travels away from the direction of the actual projectile, the more efficient the device in attenuating the sound.
Thank you again.
Good luck
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: RollingThunder51</div><div class="ubbcode-body">
</div></div>
Based on what I just read (assuming I understood it) having sound data plotted 360 degrees with DB numbers and distance points would be a much more beneficial in making a decision as to which sound suppressor to get based on sound reduction alone.
Providing I understood the article - there is a finite amount of sound as the result of the shot. Mechanical manipulation of the pressure (gasses) creates a geographic dispersion of sound. The more that sound travels away from the direction of the actual projectile, the more efficient the device in attenuating the sound.
Thank you again.
Good luck
Re: Ear vs Muzzle DB Discrepancies?
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Mo_Zam_Beek</div><div class="ubbcode-body">Can someone explain why the sound meter readings at the muzzle and the ear are different, and within that - why the muzzle readings are typically lower than the ear readings (even on bolt actions).
TIA </div></div>
The muzzle readings are not typically lower than ear readings on bolt actions.
They are typically lower than at the ear readings on direct impingement, gas operated weapons. This is because the action opens allowing gas to exit the chamber, and also some of the gas is vented through the operating system from the action.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Mo_Zam_Beek</div><div class="ubbcode-body">Can someone explain why the sound meter readings at the muzzle and the ear are different, and within that - why the muzzle readings are typically lower than the ear readings (even on bolt actions).
TIA </div></div>
The muzzle readings are not typically lower than ear readings on bolt actions.
They are typically lower than at the ear readings on direct impingement, gas operated weapons. This is because the action opens allowing gas to exit the chamber, and also some of the gas is vented through the operating system from the action.
Re: Ear vs Muzzle DB Discrepancies?
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: RollingThunder51</div><div class="ubbcode-body">Got it now many thanks (he says while buckling his seat belt)...
...I've always wondered if the creation of the ss signature pathway creates an environment that contributes to a more efficient dispersion of the muzzle blast down range. I honestly do not know. But, if it does, that could account for the spherical blast distortion as seen above....
</div></div>
That is an interesting hypothesis. I proffer that if the event could be looked at in term of a series of discreet events, we might note that the pressure waves coming off the projectile are not merely a cone segment, but a series of overlapping spherical displacements: like the muzzle blast. The previous and post displacement of the integrated events cancel each other along the axis of the flight path. The shock wave from either side of the event cancels the wave traveling from a given discrete event anywhere except normal to the flight path. The sole exception would of course be the hemisphere traveling rearward in the opposite direction of the projectile path from the origin.
Given that the gas velocity is some small positive multiple of the projectile velocity near the muzzle, perhaps the mach compression of the atmosphere by the projectile near the muzzle is minimized by this local event. The mach wave near the muzzle could be reduced or eliminated until the projectile exited the area.
If this were the case, the mach front could not propagate as close to the muzzle without a suppressor as it could with it.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: RollingThunder51</div><div class="ubbcode-body">Got it now many thanks (he says while buckling his seat belt)...
...I've always wondered if the creation of the ss signature pathway creates an environment that contributes to a more efficient dispersion of the muzzle blast down range. I honestly do not know. But, if it does, that could account for the spherical blast distortion as seen above....
</div></div>
That is an interesting hypothesis. I proffer that if the event could be looked at in term of a series of discreet events, we might note that the pressure waves coming off the projectile are not merely a cone segment, but a series of overlapping spherical displacements: like the muzzle blast. The previous and post displacement of the integrated events cancel each other along the axis of the flight path. The shock wave from either side of the event cancels the wave traveling from a given discrete event anywhere except normal to the flight path. The sole exception would of course be the hemisphere traveling rearward in the opposite direction of the projectile path from the origin.
Given that the gas velocity is some small positive multiple of the projectile velocity near the muzzle, perhaps the mach compression of the atmosphere by the projectile near the muzzle is minimized by this local event. The mach wave near the muzzle could be reduced or eliminated until the projectile exited the area.
If this were the case, the mach front could not propagate as close to the muzzle without a suppressor as it could with it.
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