Fiction:Sound-bomb

Of all of Motive's weapons, the sound-bomb -- also known as the noise-bomb or noisemaker -- is perhaps the most infamous. The sound-bomb is no conventional ordnance. Its detonation produces no shrapnel or force or fire. Rather, what it produces is noise.

Payload
A product of Motive's abstruse sciences, the noise targets the mind of any being that hears it, organic or mechanical or otherwise. The level of damage it causes scales with proximity to its source: brief or distant exposure induces migraines and nausea, whereas acute exposure, in the most severe cases, results in brain death. Those who have heard it and survived describe it as arrhythmic cacophony. Agencies familiar with similar threats would classify the noise as a cognitohazard: a particular sensory input that is dangerous to perceive.

Motive has learned how to harness the noise into its so-called sound-bombs. Ranging in size from "hand grenade" to "starship missile", each bomb is able to generate the noise across a period of seconds to minutes, killing or incapacitating everyone within its effective radius. Motive is not immune to the effects of its own bombs.

While it makes a certain sort of sense that the noise is capable of destroying organic minds, why it works on artificial ones is another matter. Robots suffer visual glitches, disruptions to balance, inexplicable errors in calculations that accumulate and cascade until a catastrophic error occurs, crashing or irrepairably corrupting even the most robust artificial intelligences. The currently accepted theory is that the act of mentally processing the noise -- however the mind functions -- somehow "infects" the thought process in an inverse quantum observer effect, propagating its harmful effects across the entire brain (or its equivalent). Supporting this theory are anecdotal reports that noise-bombs in operation disrupt psychic abilities over a significant radius.

Operation
The bomb itself is something of a curiosity. So far, the only things capable of producing the noise are noise-bombs -- no recording, regardless of fidelity, provokes the effects of the original. But how the bomb produces it is a mystery. Captured noise-bombs function perfectly well if intact, but reverse-engineered bombs (even bombs that have been dismantled and rebuilt) stubbornly refuse to activate. Close examination of their complex internal machinery suggests that sound-bombs should not physically work; key parts involved in their function must seemingly pass through each other, or undergo movements that are impossible for their articulation and mounting. This may be why noise-bombs destroy themselves over the course of their operation (reducing their interiors to scrap and molten slag), but that doesn't explain why they work in the first place.

Purpose
The purpose of the sound-bomb is threefold.
 * 1) It serves as an effective area denial weapon with no obvious effective range; a sensible enemy quickly learns to detour very far around an active bomb.
 * 2) It is a weapon of terror, demoralizing enemy combatants; there is a special sort of horror in a weapon designed to destroy the mind, particularly in contemplating what such a weapon might do to you.
 * 3) It is a "clean" weapon that neutralizes enemy combatants while leaving the surrounding infrastructure intact for later exploitation; it doesn't even leave radiation behind.

Drawbacks
As sound is very difficult to protect oneself against, the sound-bomb makes for a truly dangerous weapon. There are downsides, however.
 * 1) The bomb takes a precious handful of seconds to activate, allowing sufficiently agile people a brief window of time to destroy it before it begins full operation.
 * 2) The effects of the bomb drop off with distance, having an effective range with a shorter radius than conventional explosives -- where someone would suffer shrapnel or blast injuries, here they will only suffer temporary (though incapacitating) debilitation.
 * 3) As sound travels through vibration, atmospheric density plays a large role in the bomb's effectiveness. The thinner the atmosphere, the shorter the bomb's range; in space, the bomb is entirely useless unless it physically impacts another ship. Conversely, in places with dense atmospheres (incidentally Motive's preferred environments), the sound-bomb's efficacy increases proportionally.

Trivia

 * Inspired by the similarly-named and -functioning weapons from The Half-Made World, by Felix Gilman.