Some whales use vocal fry to find and catch their food, new research says

AILSA CHANG, HOST:

Vocal fry - you know, that low, creaky voice sound that a lot of people use? Well, new research in the journal Science now shows that the same type of vocal fry is what allows certain kinds of whales to find and catch their food. Science reporter Ari Daniel has more.

UNIDENTIFIED PERSON: Passenger P. Scotty (ph), your flight is ready for departure.

ARI DANIEL, BYLINE: I got a hold of Coen Elemans at the Copenhagen airport.

COEN ELEMANS: They normally never say anything at this airport. They're very vocal today.

DANIEL: Elemans is a bioacoustician at the University of Southern Denmark, and he says the airport is as good a place as any to hear the different ways people vocalize.

ELEMANS: What I hear is a lot of people talking. They're mostly using what's called a chest register.

DANIEL: That's our typical speaking voice.

(SOUNDBITE OF MUSIC)

UNIDENTIFIED MUSICAL ARTIST: (Singing, inaudible).

DANIEL: Then Elemans notices some music. The situation where we most often hear our higher pitched vocal register on display - falsetto.

ELEMANS: (Vocalizing) Singing register.

DANIEL: We also have a lower register below how we usually talk. That's vocal fry.

ELEMANS: It sounds like this (vocalizing).

DANIEL: All these sounds, we produce them by sending air across our vocal folds in the larynx. But this tissue vibrates differently for each register.

ELEMANS: In the vocal fry register, your vocal folds are most slack.

DANIEL: So they're thick and heavy.

ELEMANS: And they vibrate at their lowest frequencies.

DANIEL: In the falsetto register, they're stretched long and are under higher tension.

ELEMANS: And these leads to the highest frequencies.

DANIEL: Elemans wondered whether a similar thing might be at play in toothed whales - like bottlenose dolphins, orcas, pilot whales - to allow them to produce everything from whistles...

(SOUNDBITE OF ANIMAL WHISTLING)

DANIEL: ...To bursts, the sound we associate with Flipper...

(SOUNDBITE OF ANIMAL BURSTING)

DANIEL: ...To echolocation clicks...

(SOUNDBITE OF ANIMAL CLICKING)

DANIEL: ...Used to hunt for food. Now, toothed whales have a larynx, but it doesn't produce sound. Rather...

ELEMANS: They evolved some new structure that's located in their nose that generates the sounds, what's called phonic lips.

DANIEL: For decades, it's been really hard to observe the phonic lips in action, but Elemans and his colleagues have managed to do just that. They lowered a small camera into the blowholes of a few trained captive dolphins and porpoises.

ELEMANS: And we showed that there's definitely movement of these while they make echolocation clicks.

DANIEL: Then they worked with harbor porpoises that had died in the wild and saw that the phonic lips aren't controlled by muscles.

ELEMANS: Instead, they move just like our human voice, by airflow, and that's a really striking parallel.

DANIEL: Additional experiments suggested toothed whales likely have separate vocal registers, just like we do, that generate their numerous sounds. The vocal fry register is responsible for echolocation.

AGNESE LANZETTI: This is, I think, the very best research that shows how the sounds are made mechanically and to prove that the sounds are generated by air.

DANIEL: University of Birmingham evolutionary biologist Agnese Lanzetti wasn't involved in the research. Her point about air is important because when an animal like a sperm whale dives deep below the surface, its lungs collapse under the pressure. But inside the bony structure of the nose, air can continue to move around and power echolocation, says Coen Elemans.

ELEMANS: By moving all the air into the nose, these toothed whales are able to generate much higher pressures to drive the system. And with that, they can make basically the loudest sounds any animal can make on the planet.

DANIEL: And more importantly, feed themselves in the process, turning vocal fry into fish fry. For NPR News, I'm Ari Daniel. Transcript provided by NPR, Copyright NPR.