Got a Real-World Weapon, Armour or Tactics Question? Mk. XXIX

[Telok]

I don't think miles. Otherwise I'd hear a lot mor gunshots. I'd say maybe a mile on an open plain with little sound between.
Less if say a large number of insects or other noises were between them.

Adjust for buildings in the way.

I did research into vision & hearing for a game with "perception" but no rules or examples. You can check the Other Games forum, I have a DtD49k7e thread and the stuff is in the book 1 download, or you can wait until later when the 2 year old child is out of the house and I can use the computer without a hairless howler monkey jumping on me. The handgun in a suburb is addressed.

OK, snagged time. Hearing stuff is in the spoiler.

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The system is a roll & keep using d10s from 2010. The DC/TN chart is exactly the same as the D&D 5e DC chart (and about as useful), but normal people in stressful situations have 2k2 (roll 2d10, keep the best 2) or 1k1 if they're completely untrained in something that needs training. That puts normal untrained perception 50% success at DC 11, DC 5 @ 93% and DC 15 @ 27%. You're basic competent PC is at 4k3 for DC 15 @ 85%, DC 20 @ 57%, DC 25 @ 30%. Maximum is generally 10k5 who 50%s at 43.

Locating the source and understanding the content of a sound (like making out what someone said, identifying a motor as a 2-cylinder as opposed to a 4-cylinder, or figuring the direction of a safety switching off in the dark) happens at about 1/4th or 1/5th the detection range, or about 1/10th the detection range if you're unprepared or facing the other way.

To notice the sound: at TN 10, TN 20, TN 30, TN 40
whisper, library, laser shot:	5m, 10m, 20m, 40m
running tap/shower, office or forest:	10m, 20m, 40m, 80m
conversation, busy restaurant: 20m, 40m, 80m, 160m
noisy household appliance, passing automobile: 40m, 80m, 160m, 320m
alarm clock, crying baby: 80m, 160m, 320m, 640m
lawnmower, shouting: 250m, 500m, 1km, 2km
circular saw, busy highway: 500m, 1km, 2km, 4km
disco, light rioting, las cannon: 1km, 2km, 4km, 8km
rock concert, gunpowder pistols: 2km, 4km, 8km, 16km
jet engines, gunpowder longarm: 5km, 10km, 20km, 40km
grenades, rockets, collapsing towers: 10km, 20km, 40km, 80km
artillery, thunderbolts: 50km, 100km, 200km, 400km

Silencers on guns move the distance down by an amount equal to their quality level with poor quality silencers moving pistol shots down to 'light rioting' distances and best quality silencers moving it down to 'baby crying' distances.

Apply in order:

x2 TN for each:
intervening wall (without large openings)
-> background noise of a higher level, per level <-
layer of hearing protection or sound-proofing

Distance modifier:
-1k1 or +10 TN per doubling of the distance (a crying baby at 160m is TN 20)
-10 TN for each halving of the distance (a crying baby at 40m is automatic)

+5 TN for each:
intervening chunk of forest, hill, or neighborhood (outdoors)
intervening light interior door or open room (indoors)
-> background noise of the same level <-
sound absorbing features of the environment

Note: Once the TN goes over 65 go back to adding +5 to the TN instead of doubling the TN.

Examples: Someone shoots a silenced hand cannon. The gunshot is TN 10 at 2km, reduced to TN 10 at 500m for the silencer and 120m to discern that it's a hand cannon instead of an autopistol or revolver. Inside a house a kilometer away would be TN 30 (10, x2 for the exterior wall, +10 for distance) to hear it and identifying it a TN 60 (10, x2 for the wall, and 4x10 for distance). A crying baby in the next room would double those TNs (10, x2 for a wall, -20 since it's less than 20m away, and TN 0 is less than TN 30 so the baby is louder at that range). Without the silencer but still a kilometer away and inside would be a TN 10 to hear it and TN 30 to identify it. Remember, this is out in the open. In a suburb or city you would add +5 or more to the TN from intervening houses and trees, and with another doubling of the base TN if there is a busy highway within 250m or cars passing within 20m.

Bibliography

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Bibliography (just in case you really want to replicate some of this for yourself)

AD-753 600 TARGET DETECTION AND RANGE ESTIMATION
James A. Caviness, et al
Office of the Chief of Research and Development (Army), November 1972

RESEARCH MEMORANDUM, MOONLIGHT AND NIGHT VISIF1LITY
Thomas F. Nichols and Theodore R. Powers
USAIHRU, January 1964
https://apps.dtic.mil/sti/pdfs/AD0438001.pdf

Jungle Vision IL: Effects of Distance, Horizontal Placement, and Site on Personnel Detection in an Evergreen Rain forest
Dobbins, D.A. et al.
U.S. Army Tropic Test Center, Fort Clayton, Canal Zone, March 1965.

The Effects of Observer Location and Viewing Method on Target Detection with the 18-inch Tank-Mounted Searchlight, HumRRO Technical Report 91,
Louis, Nicholas B.
June 1964.

Report Bibliography on Target Detection and Range Estimation
ASTIA
Humans, Armed Forces Technical Information Agency, Arlington, Virginia, November 19 60.

Scripps Institution of Oceanography. Predictions of Sighting Range Based Upon Measurements of Target and Environmental Properties
Jacqueline I. Gordon.
http://misclab.umeoce.maine.edu/educ.../SIO_63-23.pdf

Google searches: target detection through visual recognition

https://www.google.com/url?sa=t&rct=...55T--bKi8JZffc

https://www.google.com/url?sa=t&rct=...6nWRcf5Pnw4z3D

https://www.google.com/url?sa=t&rct=...CZ5RKl3lLOzVQD

Detection of random low-altitude jet aircraft by ground observers (Tech. Memo. 7-60; AD 238 341)
https://www.google.com/url?sa=t&rct=...T02A3PZuTP8LlX

I amazes me, world militaries really care about this sorts of stuff but no RPG ever seems to make any effort to check previous research to fridge logic their see & hear rules.