And then there’s Karnak.
Karnak is an Inhuman (yes – one of those that you may be familiar with thanks to Marvel’s Agents of SHIELD) who has never been exposed to the Terrigen mists. Instead of “inhuman” super-powers Karnak is a phenomenal martial artist and mystic, able to find the weakness in anything and use it as a weapon. Like many 50+ year-old comic book characters, to dig into Karnak’s history is to court…well, not madness, but some weird storylines. Safe to say that the biggest deal recently was that he died, and was able to find the weakness in the afterlife he was in, and escape it, returning to life.
In Karnak’s ongoing series by Warren Ellis and Roland Boschi, Karnak is on a mission to find The Chapel of the Single Shadow whose disciples are holding a young boy of huge power against his will. SHIELD’s Phil Coulson has been giving Karnak a lift to the chapel aboard a SHIELD Helicarrier, and things got weird in issue #3 (available at your local comic shop or digitally at Comixology).
As the Helicarrier came within range of the Chapel of the Single Shadow, its hundreds of disciples gathered on the ground below the ship and sang a note. The sound, as Karnak described it was “like sick cats being put through one of those document shredder things.” The note was only the start of the attack, as the disciples then began shooting (sound-based?) energy bursts at the Helicarrier.
As for Karnak, he did what he does – he listened to the sound and found its weakness. Once the frequency was found, Karnak sang it into the Helicarrier’s amplification system, and the response on the ground was instantaneous. The disciples’ frequency was disrupted/cancelled, or as Karnak said, “All I needed to do was find the sound that broke the song.”
Along with “breaking” the song, Karnak also broke the singers – they apparently had massive cerebral hemorrhaging as a result of Karnak’s note and all died. The human devastation prompted Coulson to ask Karnak, “…are you Satan?” to which Karnak gave one of the best, creepy responses in comics in a while:
So anyway – let’s put the kind of creepy Inhuman everyone thought of as least likely to get his own series on the shelf for a little bit and talk about the science of sound. Specifically, how it can be cancelled and maybe even used as a weapon.
First things first – we live in a world that has the technological means to cancel sound everywhere, and that technology is most often seen in noise-cancelling headphones and similar devices. Headphones that are noise-cancelling come in two varieties: passive – which just have added soundproofing built up around the speaker, and active, which are…active.
Just a quick reminder lesson before we get started – sound is produced by alternating compressions and rarefactions (think of them as alternating smooshed-up and spread out areas of the air around you). While sound waves are a type of wave called longitudinal (the energy that is the wave itself travels in the same direction as the wave medium’s disturbance), they can be represented by good old sine waves for our purposes. Frequency means how many waves you encounter per second (and it’s measured in Hertz – 1 Hertz = 1 wave per second), with more waves per second (a higher frequency) producing a high pitch sound, and fewer waves per second producing a lower pitch sound. The higher the amplitude of the wave – the more energy the wave is carrying. Intensity of sound is measured in decibels. Pain starts around 130 and above 140, you’re literally hurting your ears. Got it? Good. There might be a quiz later.
Active noise cancelling headphones work by actively listening to the environment around you and analyzing the noise. By that we’re talking about “noise” in the acoustic sense – sound which exists as random, unpredictable waveforms. Give sound a distinct, reproducible waveform, and then you’ve got music, and that’s what you’re trying to listen to – noise…isn’t. Inside the headphones is a small computer that listens to and creates a sound that is 180 degrees out of phase with the incoming sound which is mixed with the incoming noise in real time. If you’re thinking of sound like waves on a string, the “counter sound” produced by the headphones puts a trough (low point) everywhere the noise has a crest (high point), and as a result, the two sounds cancel each other out, leaving no noise…ideally. Think of it like you’re adding a +1 and a -1 – the sum will be zero.
Noise cancelling headphones therefore contain a microphone (to hear the ambient noise you want to cancel), a computer, a power source, and a speaker. The headphone technology works best with noise at a near-constant low frequency (say, a plane engine), and in such conditions, can block up to 70% of the ambient noise. Increase the frequency range of the noise, and the headphones’ computer needs to work harder, and most likely, won’t be able to keep up. But if you’ve never tried them, next time you’re in a store with noise cancelling headphones on display, give them a try. They’re magical.
Noise cancelling technology is slowly making its way out of headphones. It takes a lot of computer power, but people like Professor Selwyn Wright is making headway on creating a “quiet zone” – an area whose ambient noise is listened to by multiple microphones, analyzed by a powerful computer, and then multiple cancelling waveforms are projected into the area. It’s no “silent ray,” but Dr. Wright’s ideas are heading in that direction. Still – the analysis and playback of the “counter sound” of multiple frequencies – in real time – is going to be challenging for everything but today’s largest computers. Currently technology works best with a near-uniform range of frequencies – the lower the better. Think jet engines in flight.
Going back to Karnak for a second, that was part of what he did we’d bet – in listening to the sound the disciples were singing, he was able to calculate a frequency that would cancel theirs, sending a waveform back at them that was 180 degrees out of phase. Part one – done.
But what about the…hemorrhage (and that’s putting it mildly)?
That’s some weaponized sound right there, and there are several forms. Perhaps the most visible is the Long Range Acoustic Device developed by the LRAD Corporation which is used by police around the world for communications and crowd dispersal. The LRAD can produce annoying and loud sounds (up to 162 decibels – pain starts at 130) that will probably give you a splitting headache, but will it split your head open? Nope.
For that, you need to go with infrasound.
Infrasound refers to the collection of frequencies below 20 Hz, where human hearing stops. Turn infrasound up to a high enough energy…around 140 decibels, and you’ll start to feel it throughout your body. Low frequency means that the distance between the waves is long, and the long wavelengths of infrasonic sound mean that it can set up an oscillating pressure system inside your body, perhaps even inside a “closed” part of your body, like inside your skull.
For example – 19 Hz is the resonant frequency of the human eyeball. Stand in the field of a 19 Hz sound wave with enough energy, and your eye will vibrate, resulting in twitching and possibly visions of colored lights in the edges of your field of vision. All of this is caused by the waves of sound that distort the eyeball’s shape, pushing on the retina, and mechanically activating random rods and cones by pressure. 19 Hz at 240 decibels would do a pretty good job shaking the whole human head in a very bad way – very possibly to hemorrhage and death.
In our world though – producing a 240 decibel sound would take a lot – a lot – of energy. For comparison, if you want to create a 240 decibel sound, you’d have to detonate a kiloton of TNT. It’s difficult to do.
But in Karnak’s world?
This is where we give a nod to Ellis and Boschi – whether it was intentional or accidental, Karnak’s waveform was made up of two waves, with one having regular, large wavelengths with high amplitude (lot of energy) and the other, showing irregular waves with smaller wavelengths. It’s almost as if it was supposed to show that, after listening to the sound from the disciples, Karnak was able to calculate the “counter” to the sound and produce two sounds in return – one to cancel the destructive sound from the disciples, and the other sound – generated specifically to kill them.
Again – we’re here only to talk about and ideally get people thinking about science, but if we were on that Helicarrier with Coulson at that moment, we’d be scared of Karnak as well. After all, he’s kind of…inhuman.
For more:
Scientific American: Could a Sonic Weapon Make Your Head Explode?
Selwyn Wright: Noise Cancellation Without Headphones
Scientific American: How do Active Noise Cancelling Headphones Work?
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