Noisy 10

[whswhs]

Originally Posted by WingedKagouti

Noisy 10 is essentially only appropriate for explosions capable of levelling cities.

That's an exaggeration, I think. Noisy 10 is 200 dB, which is powerful enough to register as an explosive shock wave. But at 190 dB, it's not a shock wave, but a very loud sound wave. And to go from 200 to 190, you have to divide the power density by 10, which means tripling the distance. So if you have 200 dB at radius 1 yard, you have 190 dB at radius 3 yards.

Now, 190 dB is nothing to laugh at! It's loud enough to rupture eardrums, and it's far past the threshold of pain. But it's not as high an overpressure as an actual explosion. Or, at least, that was what I worked out when I was coming up with that table.

[WingedKagouti]

Originally Posted by whswhs

That's an exaggeration, I think. Noisy 10 is 200 dB, which is powerful enough to register as an explosive shock wave. But at 190 dB, it's not a shock wave, but a very loud sound wave. And to go from 200 to 190, you have to divide the power density by 10, which means tripling the distance. So if you have 200 dB at radius 1 yard, you have 190 dB at radius 3 yards.

I was mostly referring to the loudness of the sound, sorry I did not make that clear. With 200 dB at 1 yard you have a sound that is still audible 50 miles away (edit: if there are no intervening objects). For something to make that much noise (if making noise isn't the primary function) it basically needs enough power to be equivalent to an explosion that would level a city.

[Pursuivant]

Originally Posted by whswhs

Each level of Noisy gives +2 to Sense rolls. Ten levels give +20. Doubling the range is -1 to Sense rolls, so +20 cancels out twenty doublings. You can hear it as well at 8 miles as you can a sound at the threshold of hearing at half an inch. I would call it 200 dB. Note that the limit of undistorted sound in air is 194 dB, so this is equivalent to an explosive shockwave.

This strongly argues that, realistically, any level of Noisy greater than 6 should be linked with an Affliction or Innate Attack.

[Anders]

Originally Posted by whswhs

That's an exaggeration, I think. Noisy 10 is 200 dB, which is powerful enough to register as an explosive shock wave. But at 190 dB, it's not a shock wave, but a very loud sound wave. And to go from 200 to 190, you have to divide the power density by 10, which means tripling the distance. So if you have 200 dB at radius 1 yard, you have 190 dB at radius 3 yards.

Now, 190 dB is nothing to laugh at! It's loud enough to rupture eardrums, and it's far past the threshold of pain. But it's not as high an overpressure as an actual explosion. Or, at least, that was what I worked out when I was coming up with that table.

194 dB is the loudest possible sounds on Earth at ground level.
https://www.reddit.com/r/askscience/...ssible_194_db/

[Pursuivant]

[QUOTE=whswhs;2382730]That's an exaggeration, I think. Noisy 10 is 200 dB, which is powerful enough to register as an explosive shock wave. But at 190 dB, it's not a shock wave, but a very loud sound wave. And to go from 200 to 190, you have to divide the power density by 10, which means tripling the distance. So if you have 200 dB at radius 1 yard, you have 190 dB at radius 3 yards./QUOTE]

Per reputable internet sites, 200 dB is as loud as a volcanic eruption, 250 dB is approximately the initial force of the Hiroshima and Nagasaki atomic blasts, 300 dB approximately that of the Tunguska Event.

[whswhs]

Originally Posted by Anders

194 dB is the loudest possible sounds on Earth at ground level.

Yes, and that's the value given in Enhanced Senses.

But "the loudest possible sound" doesn't mean that it's physically impossible to put more energy into compressing and rarefying the atmosphere, in the way that it's physically impossible to accelerate a massive body to luminal or superluminal speeds. It means that when you get above that level, you get not sound waves, but explosive shock waves, whose energy density falls off not as the inverse square of distance but as the inverse cube (and whose pressure falls off not with distance, but with the 3/2 power of distance).

It's also worth noting that louder sounds are possible on other media, such as sea water.

[Michael Thayne]

There's actually a submarine robot in GURPS Reign of Steel: Will to Live that has Noisy 10, which I'm guessing is a mistake, especially given that it's only SM +2. Flying robots mostly seem to have Noisy 4-5 (or less, if designed to be quiet). Steampunk 2: Steam and Shellfire has an SM +3 combat robot with Noisy 6.

[whswhs]

Originally Posted by Michael Thayne

There's actually a submarine robot in GURPS Reign of Steel: Will to Live that has Noisy 10, which I'm guessing is a mistake, especially given that it's only SM +2. Flying robots mostly seem to have Noisy 4-5 (or less, if designed to be quiet). Steampunk 2: Steam and Shellfire has an SM +3 combat robot with Noisy 6.

A hand grenade is around Noisy 10 at 1 yard, and its SM is negative. Of course it can only make that noise once.

[Michael Thayne]

Originally Posted by whswhs

A hand grenade is around Noisy 10 at 1 yard, and its SM is negative. Of course it can only make that noise once.

Sure. The question is whether that's realistic for a submarine propulsion system that isn't trying to create explosions.

[Phil Masters]

Originally Posted by Michael Thayne

Steampunk 2: Steam and Shellfire has an SM +3 combat robot with Noisy 6.

Which, in retrospect, was probably overdoing it. But at a certain point, you’re just saying “WILL be heard coming a long way off. Cannot be stealthy, no way, nuh-huh.” Noisy 5 might be a reasonable absolute cap for anything that is worth statting as a character, with an “Operators must wear ear defenders” sort of note attached.

EDIT: Checking the Basic Set, I notice that taking more than five levels does actually require GM permission.