Could we hear the speaking voice of a six-inch-tall human?

February 15, 2013 8:29 AM

I am considering writing a novel/story that involves the idea of people living among us who are somewhere between three and eight inches tall, but I don't know enough about the physics of sound to know if normal height humans would be able to speak to these tiny people. Would their voices be too high-pitched to hear at all, or just very difficult to understand? Would our voices be understandable to them?

If normal speech is impossible, could electronic devices allow for easy communication? Cell phones or hearing aids of some sort? How might that work?

I should add that either yes or no is an option for the story, it just changes the path I'd like it to take if we can't communicate across the size divide.

I realize that I will have to explore all sorts of biological implications of such teeny peeps, but for now I would like to get the dialog question sorted out.

posted by Rock Steady to Science & Nature (18 answers total)

We can hear high-pitched sounds from much smaller creatures (rodents, mosquitoes, birds), so...probably?
posted by rtha at 8:40 AM on February 15, 2013 [3 favorites]

Well, we can hear the yips and squeaks of squirrels and other similar-sized smallish creatures, so we would likely be able at least to hear these tiny people, if not understand them directly (assuming they're as smart as us biggers).

I'd think that the main difference would be speed -- like smaller beasties, they would be moving much faster than us, so they could probably understand and communicate with us with some "slowing down" and a lot of shouting. We would solve the amplification problem at least by the late 19th Century (if any of us knew about them then).

As for them understanding us, they would probably have to concentrate a little, but given that we're the apex thing in their environment, they'd likely devote much of their effort to doing it. It would probably be second nature for them to shift to "understanding big-people talk" mode.
posted by Etrigan at 8:46 AM on February 15, 2013 [2 favorites]

Best answer: Well, a first approximation answer would be that this is a 1/12 model human which would have a resonant chamber for the voice 1/12 as long as the full-sized human, which would result in a resonating frequency 12X the full sized human.

Middle C (near the upper end of human adult male voice & lower end of adult female) is about 262 hz and 12X that is about 3940 hz which is well within normal human hearing range.

Whether the 6-inch humans could hear us is a different and perhaps interesting question. Even assuming everything scales to 12X higher frequency (so they could hear approx 240hz to 240,000hz), they could certainly make out our speech from that basis, though they would miss some of the lows. There is probably enough info left in the upper frequencies to make out human speech with no problem, though.

Also they might be able to hear low sounds out of proportion to their size. For instance, we can hear down to 20 hz or so but the length of organ pipes needed to generate those low frequencies is up in the several tens of feet. We don't have tens of feet of tubing in our ears but we can still detect those frequencies using a few clever tricks.

(That's one reason the 1/12 scale human may not generate exactly 12X the frequency when speaking--our vocal resonant chambers use a few clever tricks, too, and probably don't scale exactly.)

Also I don't think any animals, certainly mammals, can hear up to 240,000hz. It's quite possible that they would have a hearing range quite similar to full sized humans, simply because that is the general ranges of highest interest to us mammals. of all sizes.
posted by flug at 8:46 AM on February 15, 2013 [11 favorites]

We can hear high-pitched sounds from much smaller creatures (rodents, mosquitoes, birds), so...probably?

Building on this, you could probably google around to find out what frequency small mammal noises are and work from there.

Smaller and younger things are generally able to hear high frequencies better than things that are big and/or old. Perhaps your little people would be bothered inordinately by things like the electric hum of a tv or speakers and have to adapt their lives around that. Perhaps your little people would only be able to talk to children, and kids would have to translate for adults. Depending on what kind of story you're writing, that could be a fun direction.

I also like the idea of walking across a keyboard in order to type out a message.
posted by phunniemee at 8:50 AM on February 15, 2013

Best answer: Tiny people could not simply be perfect scale models of full-size people. Biology and physics just don't work that way. The tiny people would have tiny brains, and there's no way (without some sort of magic) that they could come close to the intelligence of a full-size person. And that's just one obvious thing - there are plenty of others, like the way mass increases with height - we're the shape we are in part because of our size; a tiny creature would look very different by virtue of the different height-to-mass ratio.

If you're going to hand-wave away all of the differences imposed by the size difference, I don't think the acoustics of the vocal tract are really worth getting too specific about.
posted by pipeski at 8:51 AM on February 15, 2013 [8 favorites]

Best answer: There are several factors here. First, whether the voices of the characters will be within in the range of human hearing, which is generally 20 to 20,000 Hz. Two factors will affect this, the length of the vocal chords and the volume of the column of air in the throat.

I will assume an person of 70 inches (5'10") as a baseline. Make him 7 inches tall, and the square-cube law informs that the vocal chords will be 10 times shorter and 10 times thinner and the column of air will be 0.1% its former volume. I think it is likely that the vocal frequency would be outside the range of human hearing. If the relationship between pitch and the column of air is linear, that 262 Hz is now 262,000 Hz.

Another issue would be the volume of the Littles' voices. Normal conversation is about 60 dB when you are right there. I do not think they would be loud enough, either.

Pipeski correctly notes a number of other problems that the square-cube law introduces. For example, the surface area of his skin (which radiates heat) has decreased by a factor of 100 but his volume (which generates heat) by a factor of 1,000. They will not be ale to maintain body temperature without a commensurate increase in their metabolism. Otherwise, they would die of hypothermia on sunny days. The metabolism increase would mean they need to eat their weight in food every day. This means sleeping a lot less so they can avoid dying before waking up.

So yes, if you are going to hand-wave away all the big stuff, you can also wave away the vocal issues.
posted by Tanizaki at 8:58 AM on February 15, 2013

Seconding pipeski re: scientific accuracy.

Also, FYI, this is almost the exact premise of a series of children's books that I loved as a kid - The Littles.
posted by randomnity at 9:00 AM on February 15, 2013 [2 favorites]

Best answer: This might be the closest to a real life example: here is the speaking voice of the world's shortest woman, who is just over 2 feet tall.
posted by illenion at 9:10 AM on February 15, 2013 [1 favorite]

The tiny people would have tiny brains, and there's no way (without some sort of magic) that they could come close to the intelligence of a full-size person.

Theoretically yes, and I realize that someone who's 6 inches tall is a whole other thing altogether, BUT. People who have primordial dwarfism have tiny, tiny brains (like, baby-sized) relative to an average adult, but do not suffer any reduced intelligence as a result. So a tiny brain does not necessarily equate to lower intelligence.

Neurology is funny like that.
posted by phunniemee at 9:14 AM on February 15, 2013 [1 favorite]

Best answer: I think you might be over thinking this, unless your story is a very hard science fiction and based specifically on the idea that these tiny people are miniaturized humans, you can simply say they evolved in parallel to "regular' humans, and their voice/ears might be slightly different. Like others have mentioned, they can hear/be heard by us the same way small birds or rodents can.
posted by tylerkaraszewski at 9:30 AM on February 15, 2013

Birds produce sounds entirely differently from humans. That being said, humans and budgies can hear and understand (in a manner of speaking) each other with a little work.
posted by Devoidoid at 9:34 AM on February 15, 2013

Terry Pratchett actually deals with the communication and how the big people would appear to tiny people in his Bromeliad Trilogy.

The Nomes regard humans as quite lumbering and slow (both movement and thought) and very difficult to understand. He doesn't bother with the reverse issue though -- how the Nomes would sound to the humans IIRC.
posted by Librarygeek at 9:42 AM on February 15, 2013

I agree with flug. By a dimensional argument they'll be roughly ten times the frequency, which is about three and a bit octaves. Play it on a piano to get a feel for it. Also, the higher harmonics would be inaudible to us, rendering voices less distinctive.
posted by Wrinkled Stumpskin at 12:02 PM on February 15, 2013

Best answer: They might also spike into ultrasonic when emotional or laughing, like rats.
posted by Wrinkled Stumpskin at 12:05 PM on February 15, 2013 [1 favorite]

Best answer: Very interesting question, but I'm seconding tylerkaraszewski.

If you are requiring the reader suspend disbelief to be open to the idea of 3-8 inch people, then you can most certainly extend that to anything else about the tiny people. To the best of my knowledge they don't exist, so since you are creating them, YOU can decide the qualities they do and don't possess. Perhaps whatever is in the gene that makes them small, allows them to be heard by regular size people, or allows them to not blow away at the slightest breeze or whatever.
posted by NoraCharles at 1:56 PM on February 15, 2013

Response by poster: This is great, thanks everyone. I understand that this is a minor point compared to the other disbelief that must be suspended in such a situation, but I just thought it would be good to at least get some grounding in the "actual" physics of it before I decide how to handle it in the fictional world.

And I loved The Littles as a kid too, but this is going to be a little bit of a different scenario, in that the little people in this story live out in the open and are an accepted and normal (if a bit tricky to manage) part of the world.

I'm leaning towards having face-to-face communication across the sizes be possible, but pretty difficult due to dropping out of high/low frequencies and volume differences.
posted by Rock Steady at 2:16 PM on February 15, 2013

I suppose if they are widely known to exist, then there would be some kind of voice-transforming device readily available, kind of akin to a bat detector. And since you mentioned cell phones, there would be big and little versions of the cell phone, which pitch the voice up or down as it is required.

Low-tech version is you write them a note.
posted by RobotHero at 3:01 PM on February 15, 2013

If it was good enough for Jonathan Swift in Gulliver's Travels..... it's good enough for you? :D
posted by easily confused at 4:29 PM on February 15, 2013