The fact that each white whale has individual voice is established by Russian scientists conducting research in the White Sea. Differences between white whales' voices can be used in estimating their number.
"White whale individuals can be distinguished by the sound of voice practically like humans," - tell V.M. Bel'kovich and S.A. Kreichi from the Shirshov Institute of Oceanology. The scientists observe the animals every year in the White Sea by the Bolshoi Solovetskii Island, where their stationary is located. There dwells a population of white whales that includes many females with calves. The acoustic system consisting of a hydrophone, amplifier, and digital recorder registers communicative calls of white whales within the range from 0.06 to 20 kHz. The stable population structure is beneficial for identifying and distinguishing individual voices of the animals.
Communicative calls of white whales can be compared to human sounds. The whales make various vocal-like, voice-like, whistling, flicking, bumping, hiccupping, and smacking sounds and noises. Therefore, methods for studying human speech are to a certain extent applicable to whales. Their calls can be arranged in blocks that can be grouped at higher hierarchical levels. Certain blocks are often repeated, which makes it possible to suggest that sounds make up syllables, and syllables make up words in whales' communication.
Using the computer program "Speech Analyzer" the researchers obtained amplitude/time, frequency/time, and spectrum/time characteristics of white whales' calls. They got especially curious about vowel-like sounds that are either short like vowels in human speech or long like a sort of singing or bleating. These sounds are most characteristic of whale individuals because of differences in their duration, pitch, and timbre. Hence, they can serve as an acoustic mark of an animal.
It is curious that white whales, like people, differ by voice pitch. In the studied population, animals with high-, moderate-, and low-pitched voices constitute 20%, 50%, and 30%, respectively. The distribution of voice pitches in white whale males and females is comparable with that in humans.
The researchers have carefully studied individual characteristic features of whale voices and verified the practical applicability of that knowledge as follows. Using their acoustic device they counted voices in a flock of white whales and estimated the number of animals at about forty, which coincided with visual survey data.
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