To Decode Elephant Conversation, You Must Feel The Jungle Rumble The trumpeting roar of an elephant is loud. But scientists living with herds in the forests of central Africa say the deep rumbles that humans can't hear, but can feel, carry crucial messages, too.
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To Decode Elephant Conversation, You Must Feel The Jungle Rumble

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To Decode Elephant Conversation, You Must Feel The Jungle Rumble

To Decode Elephant Conversation, You Must Feel The Jungle Rumble

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  • <iframe src="https://www.npr.org/player/embed/432616506/432978518" width="100%" height="290" frameborder="0" scrolling="no" title="NPR embedded audio player">
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DAVID GREENE, HOST:

The natural world is abuzz with the sound of animals communicating - crickets, birds, even grunting fish. MORNING EDITION is exploring that world in our project, Close Listening: Decoding Nature Through Sound. Today, NPR's Christopher Joyce and audio producer Bill McQuay from the Cornell Lab of Ornithology have this story on the secret signals of African elephants.

(SOUNDBITE OF ELEPHANTS TRUMPETING)

BILL MCQUAY: In 2002, I went to the Central African Republic to visit Katy Payne, a biologist who created the Elephant Listening Project. I was there to record these elephants for NPR's Radio Expeditions program. Katy's team was living in shacks in the dense jungle inhabited by hundreds of rare forest elephants.

CHRISTOPHER JOYCE, BYLINE: And as I recall, Bill, you got an earful of elephant right off the bat.

MCQUAY: Yeah, I was walking through this rainforest to an observation platform built up in a tree, out of reach of the elephants. I climbed onto a platform with my gear and I set up my recording equipment. I put my headphones on and then sat there, listening.

(SOUNDBITE OF ELEPHANTS TRUMPETING)

MCQUAY: That first roar sounded close to me. But I was so focused on the settings of my recorder that I didn't bother to look around.

JOYCE: Truth is, Bill goes into a kind of trance when he records.

(SOUNDBITE OF ELEPHANTS TRUMPETING)

MCQUAY: That second roar sounded a lot closer. I thought, this is so cool. But what I didn't realize was there was this huge bull elephant standing right underneath me, pointing his trunk up at me, just a few feet away.

(SOUNDBITE OF ELEPHANT TRUMPETING)

MCQUAY: Apparently he was making a dominance display.

JOYCE: Well, maybe he didn't like being ignored.

MCQUAY: I was so busy listening, I never looked up. I never saw him. The scientists on the other platform saw the whole thing.

JOYCE: Those scientists were part of a listening culture that's evolved over the past 60 years. Payne was a listening pioneer. She had shocked the scientific world 33 years before when she discovered whale song. But listening to elephants in Africa was an altogether different thing. You had to get close to them, live with them, and, as Bill discovered, that could be scary.

MCQUAY: Katy told me about her own close encounter, during a walk in the forest.

KATY PAYNE: We suddenly heard a tremendous roar and rumble really, really close to us. And there was this elephant, huger and bigger than life, with her ears flared, rumbling and roaring at us. And we climbed a tree quite quickly.

MCQUAY: Katy was studying a mysterious kind of elephant sound. It was different from the sounds we can all hear. This was infrasound, at very low frequencies. It's more like seismic waves.

(SOUNDBITE OF ELEPHANT RUMBLING)

JOYCE: Payne had first discovered that elephants make these sounds while she was at a zoo in Portland, Ore. in 1984. She'd gone there to talk about whales. But she took time off to hang out at the elephant enclosure at the zoo.

PAYNE: And I began to realize that, every now and then, I was feeling a throbbing in the air.

JOYCE: It reminded her of an experience she'd had singing the music of Bach with a large chorus and a pipe organ.

PAYNE: I realized that that was the same feeling I'd gotten when I used to sing in the choir at Cornell in the Sage Chapel choir.

(SOUNDBITE OF ORGAN MUSIC)

PAYNE: And the organ would go low, low, low, low.

(SOUNDBITE OF ORGAN MUSIC)

PAYNE: When the pipes go down.

(SOUNDBITE OF ORGAN MUSIC)

PAYNE: You begin to lose pitch. Pitch is replaced by feeling. And I thought, maybe the elephants are making sounds too low for me to hear, but powerful enough for me to feel.

MCQUAY: Payne asked engineers at Cornell University if they had equipment that could record that low-frequency sound. They said yes. But to actually hear it, you'd have to speed it up when you play it back.

JOYCE: Payne went back to the zoo and recorded that throbbing sound.

MCQUAY: When she played it back, this is what she heard.

(SOUNDBITE OF ELEPHANT RUMBLING)

JOYCE: And that rumble occurred just as the old bull elephant was facing a female in the next enclosure.

PAYNE: And that they were calling back and forth to each other.

JOYCE: But at a frequency below what humans can hear.

MCQUAY: Infrasound is below 20 Hertz frequency, which is the lower limit of human hearing.

JOYCE: Payne wanted to decode these infrasound signals of elephants, and that's why she went to Africa. She learned that the audible calls...

MCQUAY: ... Like the one that blasted me in the tree.

JOYCE: Those are just a fraction of the elephant vocabulary. There's a whole infrasound conversation going on as well. Payne wanted to build a dictionary of that conversation. To do that, she needed to record both the elephant sounds and their behavior at the same time. So her team wired up the forest with microphones, next to a clearing where elephants often congregate.

MCQUAY: I walked through the forest with Christopher Clark. He was an engineer at Cornell University. The elephants had a habit of smashing the recording units, so Clark strung them up in the trees.

CHRISTOPHER CLARK: I'm looking for a tree that has a bifurcation, or crotch, about 25 feet up so we can throw line over it and hoist it up.

MCQUAY: Clark said being in the forest made him realize how useful infrasound was for elephants. The forest is a kind of blanket.

CLARK: What happens as the sound propagates through this dense forest, the higher frequencies are lost. And it's the very low part of the rumble that propagates.

MCQUAY: It's like feeling a pulsing bass at a rock concert.

JOYCE: Chris wrote a computer program that could sift through days worth of recordings to find the infrasound call. Then Payne could listen to them and try to match the sound with field notes on the elephant's behavior.

PAYNE: Sometimes you'll see one elephant come in and listen and listen and listen with their ears flared and stiffened. Moving their head from side to side. And you know she's listening for a relative.

MCQUAY: Eventually she could connect the sounds with specific behaviors.

PAYNE: You watch them together, and then you get more rumbles and certain behaviors - great flapping of ears, and that's a greeting. And then you can say, those rumbles are greeting rumbles.

JOYCE: Scientists suggest that the bones and membranes in the human ear are tuned to detect the frequencies of human speech. Elephants clearly can detect much lower frequencies than we can. The structure of their ear is better at detecting low frequencies.

MCQUAY: The infrasound dictionary continues to grow. Males ready to mate have a particular rumble. A nursing female looking for its baby has a different one.

PAYNE: We realized they may be coordinating the behavior of elephant populations over large areas - that they were being used over long distances.

JOYCE: A rumbling telegraph system for a far-flung community of animals roaming invisibly through the forest.

I'm Christopher Joyce, NPR News.

MCQUAY: And I'm Bill McQuay.

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