Humpback Whales “Talk”
The Sound Coming from the Water
The aquatic environment does not favor vision; however, the environment is excellent for propagating sound waves, which travel at a speed five times higher than they do through air. Because individuals are spread over extensive areas, this factor favors information exchange between whales of the same species.
Humpback whales have no vocal cords; however, they produce sound mechanically by the passage of air through the respiratory channels, especially the larynx. The combination of several sounds usually composes a type of “song” that is emitted by male humpbacks during the breeding season.
Humpback vocalizations are different from that of other species of whales and dolphins that are known as toothed cetaceans (odontocetes). These species also use a similar process for communication; however, they have special chambers at the top of their heads that they use to emit clicks and whistles, which are commonly used as a biological sonar.
The the singing of humpback whales
Bioacoustics is a research technique that captures humpback whale sounds using a hydrophone (waterproof microphone). These sounds are considered a type of “song” because they vary among different humpback populations and are composed of sound frequencies with distinct modulations. Thus, a set of sound units emitted in a fixed sequence constitute a “sound phrase.” This sound phrase is repeated several times and then replaced by another “phrase” that will be replaced by others. The song ends when the first “phrase” is emitted again, and the song restarts.
The song of the male humpbacks varies from year to year, and researchers do yet not know why these changes occur. It is believed that calves learn to sing, and this “talent” is not solely instinctive but developed within adult males.