Voices?
We all collapsed to the ground, catching our breath. Finally I turned to Jodi. “It looks like we go to Plan B.”
She drew a very shaky breath. “Okay, yeah, we’re now surrounded, the road’s gone, and they’re waving sharp stone things at us. Let’s do that Plan B.” She looked at me. “Just what is Plan B?”
“Talk to them,” I said, grinning. “I think we just might be able to do it now.”
6. Voices of the Earth
“Tell me again just how this is supposed to work, Clint?”
I should have expected Mamma to ask again. I was never sure how much of her cluelessness was an act and how much was sincere lack of understanding. I compiled the subroutine, tested it with the main one, started running it on some test data. “It’s what I do, Mamma. Signal processing is, well, it’s teaching a machine to do some of the same stuff that we do naturally. If you figure out how, sometimes you can eventually get the machine to do it better than we do.”
She continued making sandwiches for Jodi and me. “Can you give an example your silly mother could understand, dear?”
“You’re not silly, Mamma.” I thought for a minute. “Okay, try this. There’s a big party here, everyone making a lot of noise. Evangeline spills hot water on herself and gives a holler. Do you think you’d notice?”
“Well, sure enough I would! Don’t you think I could tell when one of my own children might be in trouble?”
“I know you could, Mamma. That’s what we can do with our built-in signal processing. You’ve got twenty voices, all making a ton of noise, but somehow our brains can sort out the different voices and notice when one specific voice is doing something unusual, like shouting in pain, even if the actual volume in the room should, by rights, be drowning that voice out.”
She nodded slowly. “Never thought of it that way, but you’re right. A mother can hear even a small sound by her baby over a powerful lot of noise.”
“Right. So we can program a computer to do that, too, if we know how to tell it the tricks of the trade. Turns out there’s a lot of different ways to do that.
“For what we’re doing, the important thing is that there’s different kinds of sound, what we call frequencies; high-frequency sound’s high-pitched, low-frequency’s low-pitched. I had a project I was on, once, that had to sort out human voices that were whispering at a distance of, oh, about three hundred yards. The kinds of signals I got from that looked a lot like some of the ones I was getting from Jodi’s sensors, except that these were up in frequencies you only see bats screeching on. So I’m guessing the Nomes talk way up out of our hearing range. This converter setup will shift ultrasonic frequencies down to our range, and kick ours up to the ultrasonic.”
“And I hope you’ve got everything set, because I don’t think our neighbors are going to wait much longer.” Jodi set down the heavy packs.
“Got everything?”
“Steel weapons in case they stay hostile, three sources of light—caver’s lamps, flashlights, candles and matches—radio relays, walkie-talkies, food, clothing change, rope and climbing gear, hey, you name it, plus the stuff we cobbled together out of our gear. This isn’t the first of these hikes I’ve been on, you know. Just that this mishigas changes some of the extras we need to bring. You got the code for our little universal translators, Geordie?”
“Mr. Scott, please. You know Next Gen was a weak, pale imitation. Yeah, the code should work. It’s not all that complex and I could adapt a lot of the code I already had. But it ain’t really a translator, remember; we’re not going to understand them.” I took two smooth alloy cases in rubberized jackets from her. “Oh, that’s right, we already had some of these set up for long-term monitoring.”
“What else could I use? We don’t know how long we’ll be out or where we’ll be, so it’s a good thing we had ruggedized, sealed cases for this kind of thing.” Jodi was right—in the cave environment we expected, the gadgets we brought had darn well better be awfully tough.