Air Pistol loudness question for backyard shooting
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bobby38555
- Posts: 16
- Joined: Sun May 22, 2005 8:07 pm
- Location: Crossville, TN EMAIL bobby38555@yahoo
Re: Air Pistol loudness question for backyard shooting
I was hoping for some tips to make it louder for my neighbors.
Re: Air Pistol loudness question for backyard shooting
Use a gong as a back stop.bobby38555 wrote:I was hoping for some tips to make it louder for my neighbors.
Re: Air Pistol loudness question for backyard shooting
Sound loudness is 1/radius square.
What you perceive at 1 meter and what your neighbor perceive at 15 meters away , outdoor without percussion, are
TOTALLY different.
If physics equation hold up, your neighbor could barely hear anything.
Doug, (Doug White/ MIT), could you ascertain this?
What you perceive at 1 meter and what your neighbor perceive at 15 meters away , outdoor without percussion, are
TOTALLY different.
If physics equation hold up, your neighbor could barely hear anything.
Doug, (Doug White/ MIT), could you ascertain this?
Re: Air Pistol loudness question for backyard shooting
The 1/(distance^2) is fine in an ideal situation, but it pretty much goes out the window if you have any surfaces around (like a planet, walls, etc.) The amount of sound your neighbor hears will depend an awful lot on the geometry of the path between the firer & the listener. Hard surfaces will reflect the sound, rough ones will scatter and/or absorb it. If there is a narrow alley between the two points, a lot of the sound will go right down that path, with little attenuation. Absorbing baffles might help if things are really bad.
A few examples from the real world:
1) I once shot in the sub-sub-basement of an old National Guard armory in Boston. The range was set up for 25 yards, but we were shooting a .22 league match at 50 feet. The walls were stone, about 3 or 4 feet thick. There were sets of 4 or 5 firing points in what amounted to a stone tunnel, and we were 25 feet forward of the back opening to shoot at 50 feet. There was no sound absorbing material anywhere. Firing a .22 sounded like a large cannon going off. One of the coaches had been in the Guard, and had shot .45's down there before they believed in ear protection. It's a miracle he had any hearing left at all.
2) Back in the mid 70's, Harvard University had a range that was shared by a University shooting club and the campus police. The range was 50 feet, roughly 10 firing points wide. What was unusual was that the entire floor, from the firing line down to the targets, had a several inch deep layer of crushed vermiculite, which is a sort of fluffy mineral material. When you fired a .22 there, it just went "Whump". It was extremely odd until you got used to it. There was almost no "bang" at all. Over time, the campus police got tired of sharing the range, and the shooting club was disbanded when they couldn't use the range anymore. I think they eventually figured out that the vermiculite was saturated with lead dust & unburned powder, and they had to get rid of it.
A few examples from the real world:
1) I once shot in the sub-sub-basement of an old National Guard armory in Boston. The range was set up for 25 yards, but we were shooting a .22 league match at 50 feet. The walls were stone, about 3 or 4 feet thick. There were sets of 4 or 5 firing points in what amounted to a stone tunnel, and we were 25 feet forward of the back opening to shoot at 50 feet. There was no sound absorbing material anywhere. Firing a .22 sounded like a large cannon going off. One of the coaches had been in the Guard, and had shot .45's down there before they believed in ear protection. It's a miracle he had any hearing left at all.
2) Back in the mid 70's, Harvard University had a range that was shared by a University shooting club and the campus police. The range was 50 feet, roughly 10 firing points wide. What was unusual was that the entire floor, from the firing line down to the targets, had a several inch deep layer of crushed vermiculite, which is a sort of fluffy mineral material. When you fired a .22 there, it just went "Whump". It was extremely odd until you got used to it. There was almost no "bang" at all. Over time, the campus police got tired of sharing the range, and the shooting club was disbanded when they couldn't use the range anymore. I think they eventually figured out that the vermiculite was saturated with lead dust & unburned powder, and they had to get rid of it.
Re: Air Pistol loudness question for backyard shooting
Are you sure that that is how sound radiates? It's been a while since I have studied this, but I was fairly certain that the aforementioned equation, the inverse square law, is referred to for electromagnetic radiation, such as light, and perhaps gravity if memory serves. Of course that is in a vacuum and I believe that sound would have some difficulty radiating at 1/r^2 in a vacuum :) As a physicist, I seem to remember this stuff as fairly basic, but like I said, it has been a while.
Joel
Joel
Re: Air Pistol loudness question for backyard shooting
Because sound intensity is a function of an inverse square, we need to use a measurement that describes it in logarithmic terms: the decibel (dB). This means -- as a general rule-of-thumb -- that doubling the distance from a source reduces its intensity (ΔD) by about 6 dB. This can be expressed through the formula ΔD = 10 log (distance 1/distance 2)^2
Read more : http://www.ehow.com/how_6390965_calcula ... ances.html
So, every double distance will decrease decibel by 6 dB. 1, 2, 4, 8, 16, 32meter Going from 1meter to 32meter entail 5 doubling of distance. That would decrease decibe sound by 30 dB.
Let say in an open space, what you hear with pistol at 1 meter from you is 100 dB. At 32meter away, that would be 70 dB. That would be the sound of someone opening a can of Coca Cola.
But 32meter is pretty far away. For most people, that would be two houses down the street. Your next door neighbor, let us say is 15M away, would still hear decibel in the high 70's. That is not too loud, but more like closing of a car door.
Read more : http://www.ehow.com/how_6390965_calcula ... ances.html
So, every double distance will decrease decibel by 6 dB. 1, 2, 4, 8, 16, 32meter Going from 1meter to 32meter entail 5 doubling of distance. That would decrease decibe sound by 30 dB.
Let say in an open space, what you hear with pistol at 1 meter from you is 100 dB. At 32meter away, that would be 70 dB. That would be the sound of someone opening a can of Coca Cola.
But 32meter is pretty far away. For most people, that would be two houses down the street. Your next door neighbor, let us say is 15M away, would still hear decibel in the high 70's. That is not too loud, but more like closing of a car door.