The book I mentioned also mentions how this moth counters the bat's echolocation.

Various studies of various bats - there was an interesting if torturously indirect one about the Big Brown Bat a couple of years ago - have shown that this is precisely what they do. [Big Brown Bats also can do so-called "semi-predictive" trajectory calculations, homing on the expected location of an object which they can no longer sense: object permanence and trajectory prediction. I don't know how common an ability that is; object permanence isn't a universal trait amongst animals, I know.] I'm not a professional ethologist, but from what I know, trajectory prediction is present in most vertebrates, in one form or another. [I say, "in one form or another" because, for example, the squirrel doesn't necessarily need to track prey on the wing and go to "where it will be," but it does the same type of calculations for its own leaps.] I would venture several invertebrates - I'm thinking mostly along the lines of the predatory cephalopods - possess similar trajectory projection abilities. It's actually not that rare an ability, and most animals are a lot smarter than we necessarily realize. They should be pretty capable: every single one of them is descended from three and a half billion years worth of ancestors, not one of which died before having offspring.

Someone mentioned above that the system could use predictive software to perform the same tasks, taking velocity and distance measurements and predicting, "If the target has, during the 'lag' period [whose duration can be determined by distance], continued to do what it was doing, this is where it will be." That person was right on: algorithms like this exist today [anyone here could write one], and some of them are pretty clever. Game mechanics for this type of system would be trivial to design.


This may be a good argument with respect to ultrasound, specifically - perhaps its limitations are inherent, and not technological - but using this logic, why aren't Wired Reflexes used more often today? Sometimes the difference between today's technology and SR's is because we just haven't gotten there technologically yet. I have confidence that ultrasound imaging for humans will continue to develop until it is a useful technology for various applications...unless its necessity is superceded by some other development, as so often happens. [The Fourth Earl of Dundonald: "I've finally found a way to make tar out of coal [instead of wood] that you can spread on the bottoms of your tropics-bound ships to protect them!" British Admiralty: "We're just using copper now. Sorry."]

That said, perhaps there are valid and inherent reasons that ultrasound imaging won't be practical, ever, but that would surprise me deeply, given its clear utility in various animal species.


Yeah, but for every sense, there is a countermeasure. You can do precisely the same for sight, or for hearing. [Some people can do this for scent, and it won't even cost you "a buck fifty."] Echolocation has a countermeasure that I find particularly intriguing, which I'd have some difficulty adapting for other senses: if you artificially accelerate or delay a bat's ultrasound, you can get it to try to land on things that are not where the bat thinks they are. This is done, of course, in controlled lab environments, but with super-future-handwavium, I don't see it as being particularly impossible in a broader environment, either.

Wow, so much to respond to. That'll teach me to not check on a topic for a while.

I'd have to agree that the penalty for using ultrasound comes from the second lag that you get from a target being 170m away. I'd guess this is also why there is a light modification for ultrasound, because it'll point out about where a target is, but it relies on your eyes to pinpoint the exact current position (Speed of light >> speed of sound).

In theory it seems like ultrasound should use complex rules for penelties with using it based on how far away the target is (And how many IPs you have. Having a 1 second delay on the position of the target is alot when you are acting in a .75 second time frame.), so the penelties provided are a simplification that run on the assumption that you have sight on the target. The darkness penalty should be negated for melee combat at least though. At that point the delay is only going to be a tiny fraction of a second, oh well.

I'd imagine this delay is one of the three big reasons that we don't see ultrasound in use in the military. The others are lack of technology to make it easily usable as an overlay in goggles for normal vision and good old $$$.

Another range issue is volume. An incredibly tiny number of animals produce light to see by. This is because it's very expensive to do so: you produce light which emanates out in a sphere, with the power of that light being distributed across the surface of the sphere, thus weakening in power by the square of the distance to the source; this wave then contacts an object and bounces back, emanating outward in another sphere, again weakening in power by the square of the distance back to the original source. Thus the emitted radiation is returned reduced by the fourth power of the distance.

Sound intensity - not pressure level - works the same way, which means that in order to get reasonable range, you need serious volume, and that can be dangerous. You can constrict the beam of sound, as with a megaphone, but that still means that anything near the emitter and in the beam could be deafened or even killed. [The latter requiring serious, serious volume.] Even then, your own ears are very close to the emitter; bats solve this problem by effectively plugging their ears whenever they open their mouths to emit, much like radar systems do to prevent damage to the antennas. You wouldn't really have this option with [unmodified!] human ears. You could have some sort of frequency-selective hearing damper, but the last thing you want is a piece of protective gear whose loss means you can't use some other tool, or let anyone around you use that tool.

So there are serious issues for ultrasound imaging in air for military applications to overcome. Not necessarily insuperable, but enough that Shadowrun requires, for me, some suspension of disbelief.

I didn't think the loud sound would be an issue if it was inaudible. Besides, at worse you get some ear plugs, and that can easily allow it to go up to "Rock concert." volume. I'm sure ear plugs are fairly standard to help with all the noise of guns being fired anyway.

Nope. Even if your ear can't vibrate in such a way as to make meaningful resolution of the sound, it's still vibrating, and damage can still be done. Higher dB levels vibrate you so much you heat up, and can die from such exposure. [Although dB is a logarithmic scale, so the required 180dB is very high indeed!] This report from Health Canada has the relevant figures and cites.


Right, but you either get hearing protection that isolates only the ultrasound - technically more difficult, but not impossible - or you deafen yourself to all sound, which you don't want when you're running about in combat. Either way, you're wearing something that, if you take it away, removes your ability and the ability of all your teammates to use their imaging system. More significantly, while it's possible for you and your team to wear selective ear protection that cannot be damaged or removed, you can't give them out to every civilian, or indeed your opposition: you would deafen them, which is a big no-no either way.

Another point: What happens when two ultrasound systems are active at the same time? Does this cause interference and render both systems useless? Or can the user chose a different frequency?

Wouldn't you know it? Bats got there first, again.

Multiple systems probably wouldn't be an issue; smart signal encoding (probably with rapidly shifting multi-frequency pings) would ensure each system recognizes its own bounces. However, you could probably use one system (or a simpler special purpose device) to "glare" another, in a manner similar to a flashpack, by simply playing back amplified / distorted versions of the pings it sends out at high volume. Coding wouldn't help with that, because you'd simply be echoing whatever coding the system you were jamming sent out.

edit- or, as said with bats, ping information that "doesn't make sense" could be chucked, and systems could be spoofed with fake echos. I expect the bats could be "glared" as well, but I doubt the scientists wanted to try hurting the bats ears like that.