Baterra communicating with subsonics?

[Makuta_of_Oz]

I recently discovered on BS01 that baterra can communicate with each other through subsonics. According to my MacBook's dictionary app, subsonics is basically low-speed sound. How exactly would that work?

[Katuko]

I believe they might simply have meant sound that is too low for others to hear, not that the sound waves are actually traveling slower than normal. Sci-fi writers tend to grab a cool term and misapply it. In this case I believe the Baterra use noises that lay below 20 Hz, which is generally accepted as the point where a normal human stops being able to detect the low-frequency tone. These frequencies are called infrasonic, the same way we call it infrared when the wavelength of visible light falls below our eye's detection range (and conversely, ultrasound and ultraviolet at the opposite end of the spectrum, along with supersonic, transonic, hypersonic, etc). Calling it low-frequency "infrasound" would therefore be more accurate - and sensible - than "subsonic". I mean, if it actually went slower than normal sound (itself slow compared to electronic communication and telepathic abilities) then there would be little point in using it for communication.

 

Wikipedia has the following to say:

20 Hz is considered the normal low-frequency limit of human hearing. When pure sine waves are reproduced under ideal conditions and at very high volume, a human listener will be able to identify tones as low as 12 Hz. Below 10 Hz it is possible to perceive the single cycles of the sound, along with a sensation of pressure at the eardrums.

 

[...]

 

One study has suggested that infrasound may cause feelings of awe or fear in humans. It also was suggested that since it is not consciously perceived, it may make people feel vaguely that odd or supernatural events are taking place.

The Mythbusters tested that last part by setting up a few identical huts and playing a low-frequency noise in one of them. They put it at such a level that it was inaudible, but if you knew it was there you could feel the vibrations from it. Test subjects were told about a ghost that haunted one of the huts, and each person then spent a certain amount of time in each hut. In the end only a few of them identified the rigged hut as the one with the "ghost", though, so the connection between low-frequency sound and feelings of uneasiness were not possible to confirm (and though the hut felt "weird" once people knew of the vibrations and were searching for them, the exact threshold would likely be different from person to person anyways). Still, this is a relatively common urban myth, so it might be that the Baterra speaks in low frequency simply because it is believed to be more intimidating. If you tune it up just slightly into the audible range, you would get deep, rumbling bass.

Edited May 5, 2014 by Katuko

[Chro]

Basically it's just like the Vahki, right?

[Katuko]

Basically it's just like the Vahki, right?

If I'm not mistaken the Vahki talk at an incredibly fast and high-pitched rate, which would make them use high frequency (ultrasonic) speech. But yes, same concept: Inaudible frequencies. I have no idea what the Matoran hearing range is, but for simplicity's sake I imagine we could say it is much like that of humans.

[Chro]

Oh. Guess I got that backwards. Similar principle though.

[Pohatu: Uniter of Stone]

What frequencies are considered subsonic in the Bionicle Universe, though? If Baterra do comunicate with subsonics, then wouldn't Agori (and Matoran later on) feel vibrations but not hear any noise?

Edited May 5, 2014 by RahkshiToa88

[fishers64]

What frequencies are considered subsonic in the Bionicle Universe, though? If Baterra do comunicate with subsonics, then wouldn't Agori (and Matoran later on) feel vibrations but not hear any noise?

That's correct, if the Battera really do communicate in "infrasound".

 

Although if they do so, couldn't they do both? Send sound waves that are very slow with lower-than-audible tones, that way no vibrations would be felt? That seems most consistent with the storyline portrayal.

[Katuko]

Although if they do so, couldn't they do both? Send sound waves that are very slow with lower-than-audible tones, that way no vibrations would be felt? That seems most consistent with the storyline portrayal.

You cannot usually feel these sound vibrations anyways, as the speaker playing the noise frequency was specifically ramped up in amplitude for experiments. It's the same with normal speech: We hear it, but we don't usually feel the vibrations in the air. In order to do so you need to play our speech at very loud volume.

 

As such, having a frequency below 20 Hz (or certainly below 12 Hz, if we consider people with exceptional hearing) would make a Baterra inaudible to a human ear. No vibrations detectable to our senses. This would still make the sound travel at its usual 343 metres per second in dry air. Making it subsonic would not make it any more undetectable, it would just unnecessarily slow down communications and potentially make a long-distance shout arrive too late. Granted, even at 100 m/s short-range communication would probably be viable. But more travel time for the sound means more potential for errors, even if we are talking about differences that are <1 second, and especially if you are a fair distance apart and need a reply ASAP.

 

Fun fact: in freshwater sound travels at a far greater 1497 m/s due to the medium the waves are being distributed through. Water molecules, making up a liquid, are packed more densely than air molecules. Thus the pressure from the sound can be transferred from molecule to molecule much quicker than in a less dense medium. At deep sea levels pressure causes sound to travel even quicker. In aluminium sound travels at 6420 m/s! Still, the density of the material also causes the sound wave to die out more quickly, as every molecule moving will require energy to do so, and not all energy will be transferred in the same direction. Plus, many materials reflect sound as well, and therefore, although sound can travel quickly through aluminium, it does not reach very far when faced with an aluminum wall in its path.

[bonesiii]

Well, this is an interesting find. I've theorized that they might have used something like radio. (Might need to consider an edit to one part of my retelling about this... unsure...)

 

To RT88's question -- if you're asking if this could give away that Baterra are nearby, I'd say so, but I'd also not assume Baterra always feel the need to communicate while they're in range of a target. Probably only if the target does something they didn't already plan for so they need to change their tactics. When Tuma realized that trick about uprooted trees, for example, and didn't just flee from the trees into the real Baterra, I imagine they probably communicated at that point. But had he just ran from the trees, probably they wouldn't have needed to say anything. But it depends on a lot of things like the medium of the ground you're standing on, how sensitive your sense of touch is, volume, etc. so it isn't a safe bet.

 

Probably you'd be best off with some kind of "Baterra talk detector" device, although a more powerful scanner able to see through their shapeshifting would be much safer.

Edited May 6, 2014 by bonesiii