Dolphins and other toothed whales such as orcas use a “high-pitched voice” similar to that of Kim Kardashian and Katy Perry to capture prey in the depths, a new study says.
Although previous research has shown that these marine mammals use sound that travels far and fast underwater to hunt prey, the range of their rich vocal repertoires remains a mystery.
The new research published in the Journal Science on Thursday by scientists at the University of Southern Denmark, toothed whales have at least three voice registers like humans.
These include the vocal fry register, also known as the creaky voice, which produces the lowest tones, the chest register which is similar to our normal voice, and the falsetto register which produces even higher frequencies.
“Vocal fry is a normal voice register that is often used in American English. Kim Kardashian, Katy Perry and Scarlett Johansson are well-known people who use this registry”, explained the co-author of the study, Coen Elemans.
The researchers found that toothed whales particularly use the vocal register of their calves to produce their echolocation calls to reflect sound and capture prey.
“During vocal frying, the vocal folds are only open for a very short time, and therefore very little air is needed to breathe to use this register,” said Dr. Elemans.
This economy in using available air makes this voice recording especially ideal for echolocation, the scientists said.
While hunting, toothed whales like orcas dive up to 2,000 meters deep and are known to catch more fish in the process than the human fishing industry.
In these deep, murky waters, the creatures produce short, powerful, ultrasonic echolocation clicks at rates of up to 700 per second to locate, track and capture prey.
“During deep dives, all the air is compressed to a small fraction of the volume at the surface,” said Madsen.
“Thus, vocal fry allow whales to access the richest food niches on Earth; deep ocean,” she added.
While this squeaky voice register might be considered “annoying” or “overbearing” in humans, vocal fry helped toothed whales become an evolutionary success story.
“Some species, like orcas and pilot whales, make very complex calls that are learned and culturally transmitted like human dialects,” said Madsen.
Although, more than 40 years ago, toothed whales were thought to make sounds with their larynx, just like other mammals, researchers later discovered that these animals somehow use their noses to produce sound.
In the new study, scientists found that toothed whales have an air-powered sound-producing system in their nose.
“Evolution moved it from the windpipe to the nose, which allowed for much greater conduction pressures — up to five times what a trumpeter can generate — without damaging lung tissues,” said Dr. Madsen.
“This high pressure allows toothed whales to make the loudest sounds of any animal on the planet,” added Elemans.
When whales dive more than 100 meters, their lungs collapse to avoid compression sickness and they rely on air found in the nasal passages of the skull.
The researchers said this air pocket provides a small but sufficient airspace to produce echolocation sound at astonishing depths of 2,000m.
To make sound at this depth, whales pressurize air in their bony noses and let it pass through structures called phonic lips, which vibrate like human vocal folds.
That acceleration, the scientists said, produces sound waves that travel through the skull to the front of the head.
The researchers filmed the phonic lips using approaches such as using trained dolphins and freely moving wild animals.
“It took us nearly 10 years to develop new techniques and collect and analyze all of our data,” said Dr. Elemans.