aStudy published in the journal science on March 2 solved one of the biggest mysteries about toothed whales. After decades of doubting how these animals make sound underwater, research has shown they have evolved the ability to operate in three different vocal cords – just like humans.
Vocal apparatuses are the different ways of producing sound from certain vibrational patterns of the vocal cords. Among toothed whales, such as dolphins and orcas, the basic (also known as a “squeaky voice”, which produces the lowest tones), chest (compared to our normal voice) and falsetto (which produces low frequencies). higher).
Toothed whales have developed a system for producing sound through the nasal air passage, which works naturally analogous to the production of sound through the larynx, which is common to other mammals. This difference is due to the evolution of whales, whose ability was transferred from the trachea to the nose, allowing much higher driving pressures—up to 5 times what a trumpet player can generate.
An image depicting how toothed whales make noise on the seabed — Photo: SDU
Vocal discs are useful for whales to communicate, locate and hunt by acoustic tracking. Normally, the most used frequency is the fundamental, in which the vocal folds are open for a short time, requiring very little air to breathe and make the sound.
This “economy” is necessary to promote sonar since, in deep dives (up to 2,000 meters deep), all the air is compressed to a small fraction of the volume at the surface.
“While the core record may be controversial among people and may be perceived as annoying or ‘imposing’, it was undoubtedly part of the evolutionary success story of toothed whales,” explains Coen Elemans, lead author of the study and a professor at the University of Southern Denmark. . .
Another important discovery was that the high pressure exerted under water allows whales to make louder sounds than any other animal.
To make sounds, toothed whales force air into their bony snouts and let it pass through structures called vocal folds, which vibrate just like human vocal folds. Its acceleration produces sound waves that travel through the skull to the front of the head.
Another use of echolocation is related to social communication, for which toothed whales use other frequencies and a huge variety of sounds. Killer whales and pilot whales make calls so complex that they are learned and culturally transmitted like dialects among their groups.