The cry of whales can travel for hundreds of kilometers underwater because water is a better conductor of sound than air. Sound waves propagate more efficiently and over longer distances in water due to its density and composition.
Water is a great conductor of sound due to its high density: the molecules are close together, and sound easily travels from one to another. Underwater, sound travels about four times faster than in air, at around 1500 meters per second. Moreover, since water absorbs very little acoustic energy, sounds fade slowly and travel much farther. As a result, the powerful calls of whales can cover enormous distances without losing much strength.
The secret of whales lies in their ability to produce sounds at very low frequencies, often well below those detectable by the human ear. These low sounds have particularly long wavelengths, allowing them to navigate obstacles such as seabeds or rocky formations without much attenuation. In other words, the lower the frequency of a sound, the less energy it loses while traveling through water. As a result, these whale songs can easily travel miles, even hundreds of miles, and are perfectly suited for long-distance communication. And that's quite handy when you want to call your friends or flirt from a distance in the vastness of the oceans.
Underwater, there are types of "sound highways" known as sound channels or SOFAR channels. Essentially, these are layers in the ocean where sound travels exceptionally well due to specific combinations of temperature, pressure, and salinity. Instead of dispersing, the cries of whales bounce along these channels, allowing them to carry their songs hundreds, if not thousands, of kilometers without losing much intensity. Just imagine a natural underwater acoustic tunnel, especially useful for whales trying to communicate over long distances. These channels were identified during World War II by the military, before realizing that whales had been using them for millions of years!
Sound travels faster in warm water than in cold water. When the temperature rises, the water molecules move more vigorously, facilitating the transmission of sound vibrations. A thermal difference between water layers can even create an acoustic boundary, which literally guides sounds over impressive distances.
The same goes for salinity: the saltier the water, the denser it becomes, which directly influences the speed of sound. These density variations caused by salt can create specific pathways, with sounds then following these underwater acoustic corridors over hundreds of kilometers.
Whales use their long-distance songs to convey essential information to the group, such as the location of a food-rich area or signals for potential mating. Communication over very long distances also helps maintain a strong social cohesion among individuals in a group, even when they are spaced several dozen, or even hundreds, of kilometers apart. This ability to send messages over great distances aids in coordinating their seasonal migrations and locating other distant groups, which increases their chances of survival and facilitates their reproduction. In short, facilitating long-distance acoustic exchanges is key to the social functioning and sustainability of whale populations.
The loudest sound ever recorded comes from a blue whale, reaching about 188 decibels, which is louder than a plane taking off (around 140 decibels)!
Researchers are using hydrophones (underwater microphones) to listen to and monitor whale songs, thereby gaining a better understanding of their migrations and social behaviors.
Unlike light waves, sound waves travel much more effectively in water, making sound the best means for whales to communicate over long distances underwater.
Each population of whales has its own distinctive songs; thus, marine biologists can recognize whales from different oceanic regions from a distance simply by listening.
Underwater, visibility is very limited, sometimes reduced to just a few dozen meters. In contrast, sound can travel far due to the density and special physical properties of saltwater, allowing whales to stay in contact over great distances.
Yes, unfortunately, human activities such as maritime traffic, oil exploration, and military sonar exercises create significant underwater noise pollution. This can disrupt whale communication, affect their behavior, and reduce their vital acoustic space.
No, each species has its own sound characteristics, such as the duration of calls, tone, frequency, and complexity of songs. For example, humpback whales are famous for their complex melodic songs, while sperm whales produce powerful clicks for echolocation.
They primarily use hydrophones—sensitive underwater microphones—to record the vocalizations of whales. These devices allow researchers to analyze the structure, frequency, and temporal variations of the songs, thus helping to better understand the behavior and movements of these marine giants.
Some whale songs, particularly those of blue whales or humpback whales, can easily travel hundreds or even thousands of kilometers due to the unique acoustic properties of ocean water.
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