It's my contention that someone under the effects of a Stealth spell should be imperceptible to sonar and/or ultrasound. It is a physical spell, however, so it wouldn't fool an astral perceiver.

The Silence spell already mentions that it will jam sonar, so I think there is a precedent.

Agree? Disagree?

Stealth spells don't make you invisible, per se. Usually they give the person or entity trying to spot you penalties. You become 'invisible' when they don't have enough dice to succeed at spotting you.

There's already a spell that works against ultrasound. Its the one that makes you quiet. Think its in the main book. And yeah, it does work against ultrasound. Its spelled out somewhere, possibly in the security section. I recall seeing a phrase to that matter

If sensors are a problem, then just pick up an extended range Detect Sensors and Slaughter Sensors. Problem solved.

Cue classic movie scene of a guard watching security cameras and one after another turns to fuzz.

"Huh, that's not normal. Well, at least we know that no one is sneaking in to the place."

I'm just imagining the grizzled lone star vet, chewing on the butt of his cigarette, while the rookie is puking into dumpster at the sight of all those poor sensors, their bits and wirings all ripped apart. "It's days like this, this mindless slaughter, that make me regret joining the Star, Kid." Cue retching from the rookie.

Yeah, because nothing says 'no intruders' like the systematic failure of cameras in the order that they view a particular path.

It's better than the camera views switching to a view of darkness, broken only by the glow of a pair of evil eyes.




-k

Don't forget that slaughtering cameras is just as difficult as powerballing them. You still have to see them and overcome their OR normally. All you get for the specific spell is a bit less drain. Hardly worth the karma

Also this.

Then they just might think they're seeing things/going stir crazy. I don't know how many guards would call something like that in right away.

"Yes. Pitch black. Except for the eyes. Evil eyes. Glowing red. Like they wanted to eat my soul or something. No, I haven't been experimenting with drugs. No, I don't have a history of psychosis in my family. Well, yes, my uncle is in a mental ward but... two weeks mandatory vacation?"

http://www.youtube.com/watch?v=3ZERiV0nw0c&t=1m38s






-k

This is why a clever hacker create some false alarms in the 24-48 hours before the actual run. When the run then goes, the guards may well just go "bah, it's another system glitch. log it for maintenance in the morning".

If the target doesn't get more hits than the caster on an Intuition + counterspelling, then the caster is effectively imperceptible, i.e. inaudible. You might be thinking of the Camouflage spell, which only give people penalties to see you.

Here's from the spell descriptions in the book: Invisibility: "This spell makes the subject more difficult to detect by normal visual senses" and for Stealth: "Stealth makes the subject less audible to normal hearing... The subject moves in silence, making less or no noise."

It sounds to me like the spells accomplish the same thing, only one for vision/light, the other for hearing/sound.

Yes, that would be Stealth, the one I referred to in the OP. You may be thinking of Silence, which is basically the Area-Effect versions of Stealth. I also mentioned this in the OP. It does, in fact, say that "Silence affects technological devices and is useful for jamming alarms, detection devices, sonar, and tactical communications, as well as technological sonic weapons."

My contention remains that since Stealth is basically the single-target version of Silence, it should render the target inaudible, and therefor imperceptible to "detection devices, sonar... as well as technological sonic weapons."

This also brings up the interesting point that a Darkness spell could conceivable reduce the effectiveness of a laser fired through it, and that a laser could go right through a person under the effects of Improved Invisibility. That is, assuming the OR threshold was met.

Sure, that'll do it, but it's irrelevant to my OP: Does the Stealth spell render you imperceptible to Sonar and/or Ultrasound. I believe it does. If I'm correct, then there is no problem to be solved by learning 2 other spells.

Anyone have anything to say about that?

Yeah, It makes you "invisible" to sonar the same way a cloud of darkness makes you invisible to camera. It might be able to see you, but a cloud of darkness walking down the hallway still looks suspicious.

That's Silence, not Stealth. Stealth is In-aud-ibility.

Yeah, so you emit no sound. On an ultrasound sensor, that shows up as omething an Infinite distance away, as you bounce no sound back at it. the sound doesn't flow around you.

Maybe it does. There's no meaningful physics in SR4 magic. It just works. Unless you think that Invisibility makes you a black shape?

This is a good point. If you make no sound, does that mean that sound waves pass by you (like Improved Invisibilty), or they just stop when they hit you (like a cloud of darkness)? I think you could be correct here. If the Stealth spell only affects you, then sonar and ultrasound should be able to detect you by the "dead zone" you create. It might, however, still reduce the power of a sonic attack targeted at you.

In this case, the Spell might still hide you if you're in a wide-open space.

Well, Improved Invis actually states that it "creates an actual warping of light around the subject", which sounds like physics, and explains how it works. Stealth, however, only says that it "makes the subject less audible to normal hearing". If we assumed that Stealth somehow bent sound waves around the subject, it would make sense that they would be imperceptible to sonar and ultrasound, but I'm not necessarily making that assumption. That's why I'm asking here.

I admit I'm nitpicking, and it might not ever come up in my own, or anyone's game, but I thought it would be an interesting discussion, and that's why I'm here

Presumably, sound and light are equally easy to work with. If Stealth isn't like Invisibility, someone should make a spell that is.