At the Copenhagen airport, Coen Elemans awaited the departure of his flight. The intercom broadcast a steady stream of safety and passenger announcements. Elemans, a bioacoustics expert from the University of Southern Denmark, stated, “Usually, nobody speaks at this airport.” He claims that the airport is a good place to observe people’s vocalisations on a day when there is a great deal of conversation.
He observes that many people are speaking. They predominantly use what is known as a chest register. This is the typical way we speak. Elemans then hears the sound of music. It is when our higher-pitched vocal range, or falsetto, can be heard most often. Moreover, humans have a lower register than the frequency range in which we typically speak. This phrase is vociferous.
It is commonly understood in English as something that modifies the sentiment or attitude of what is expressed. It is something for which some individuals, such as Leonard Cohen and Kim Kardashian, are well-known. This, according to Elemans, alters the meaning of words in other languages, such as Danish.
By moving air through the vocal folds in the larynx, we are able to produce all three of the following sounds:
The vocal crackle, the chest voice, and the falsetto (a structure that allows air to pass from your throat to the rest of your respiratory system). The vocal folds vibrate differently for each register. “According to Elemans, when you are in a vocal fry register, your vocal folds are thick, heavy, and tremble at their lowest frequencies. In the falsetto range, they are additionally stretched and under intense tension.
Consequently, the most significant frequencies follow.” Elemans pondered whether a similar mechanism that allows toothed whales (such as bottlenose dolphins, orcas, and pilot whales) to produce a variety of vocalisations also operates in these animals. Whistles, bursts (the sounds we associate with Flipper), and echolocation click sound pulses are examples of these sounds.
According to Elemans, these clicks function “more or less like a flashlight to scan their environment with a highly focused beam.” Even though toothed whales possess a larynx, it is inactive. Elemans assert that they have instead developed a “new structure that is placed in their nose and makes the sounds—called phonic lips.”
Observing the phonic lips in action over a long period of time has been challenging. Due to technological limitations, we are unable to observe whales at the depths where they commonly feed. However, Elemans and his colleagues developed a variety of tests to examine these animals’ interiors. In the latest issue of the journal Science, they present their findings.
They began by inserting endoscopes into the blowholes of a few dolphins and porpoises held in captivity and trained. The tiny camera had to get close enough to the phonic lips in order to capture them quickly; it did not have to travel very far. Elemans concludes, “And we demonstrate the movement of the [lips] during the production of echolocation clicks.
They needed recently deceased animals for their upcoming study. Elemans responds, “That is a tremendous obstacle.” When a person dies, they typically sink. Due to the lack of access to new tissue, studying their physiology is extraordinarily difficult. Elemans and the others, however, collected harbour porpoises that had died in the wild by collaborating with marine animal stranding networks, primarily in Germany. Following this, they made phonic lip movements with air.
“We demonstrated that these phonic lips are not moved by muscle control, unlike when a cat purrs for instance. In contrast, they are produced by airflow, just like human speech. Indeed, that is a remarkable analogy.” Further research combining vocalisation analysis and a type of CT scan revealed that, like humans, toothed whales likely have distinct vocal ranges that produce their diverse sounds.
In addition, the various registers serve different purposes. The team discovered that echolocation in toothed whales is caused by the vocal fry register by recording the sounds of wild animals during their dives (by attaching acoustic tags to specific animals) as well as those of trained porpoises and dolphins.
According to Kelly Benoit-Bird, Science Chair at the Monterey Bay Aquarium Research Institute, “this work’s strength is that it integrates field observations of [toothed whale] sounds and laboratory studies of physiology with our understanding of the evolution of marine mammals to provide a clear, comprehensive picture of how dolphins produce the essential, diverse repertoire of sounds for their survival.”
Benoit-Bird, a non-participant in the study, emphasises how the researchers approached this scientific issue from multiple vantage points. The picture of dolphin sound creation has finally emerged as a result of work that assembled the puzzle pieces, determined how they fit together, and filled in the blanks.
Evolutionary biologist Agnese Lanzetti, who was not involved in the study and works at the University of Birmingham, concurs. She claims that “this is the best research demonstrating how the sounds are produced mechanically and to demonstrate that these noises are formed by air.” In toothed whales, air behaves differently than it does in our bodies while we are on land.
A sperm whale’s lungs will burst under pressure when it descends several thousand feet below the water’s surface. Yet, air may still circulate and power echolocation inside the bony nasal structure. “According to Elemans, “these toothed whales can generate much larger pressures to operate the system because they move all the air into the nose. And because of that, they can produce some of the loudest animal sounds on earth.”
